bluuebunny/crossref_metadata_2025 huggingface dataset:
Serum Brain-Derived Neurotrophic Factor Concentrations in Lean and Overweight Children and Adolescents
Authors: El-Gharbawy Areeg H. , Adler-Wailes Diane C. , Mirch Margaret C. , Theim Kelly R. , Ranzenhofer Lisa , Tanofsky-Kraff Marian , Yanovski Jack A.
Published: June 2006

Context: Brain-derived neurotrophic factor (BDNF) and its receptor appear to be important components of the leptin-signaling cascade involved in energy homeostasis, and mice with BDNF or TrkB gene haploinsufficiency have excessive adiposity. Little is known about the relationship between adiposity and BDNF, particularly in children.

Objective: The objective of the study was to study the association of serum BDNF with measures of adiposity in children.

Design/Setting/Patients: BDNF was determined by a sandwich-type ELISA after an overnight fast in convenience sample of 328 subjects, aged 3–19 yr enriched for extreme obesity. In 43, BDNF was also measured before, and again 1 h after, consuming a high-energy content (787 kcal) milkshake.

Main Outcome Measures: Measures included associations between BDNF and measures of adiposity.

Results: There were no significant univariate associations between log BDNF and adiposity measured by body mass index (BMI), BMI-Z score, or fat mass. However, in an analysis of covariance accounting for age, sex, race, pubertal status, and platelet count, BDNF was lower in overweight children (mean ± sd, 39.8 ± 24.8 vs. 47.0 ± 25.4 ng/dl, P = 0.03); in multiple regression analyses with log BDNF as the dependent variable, BMI (P = 0.03), BMI-Z (P = 0.01), and body fat (P < 0.02) were all negatively associated with BDNF once age, pubertal status, and platelet count were included in the model. Ingestion of a meal did not significantly alter serum BDNF 1 h later (P = 0.26).

Conclusions: Serum BDNF is lower in extremely overweight children and adolescents than those of normal weight. It remains to be determined whether obese individuals with low serum BDNF for age and platelet count have mutations that alter BDNF function.
Comprehensive Mutation Scanning of NF1 in Apparently Sporadic Cases of Pheochromocytoma
Authors: Bausch Birke , Koschker Ann-Cathrin , Fassnacht Martin , Stoevesandt Johanna , Hoffmann Michael M. , Eng Charis , Allolio Bruno , Neumann Hartmut P. H.
Published: June 2006

Background: Pheochromocytoma is a rare manifestation in patients with neurofibromatosis type 1 (NF 1). The 57-exon susceptibility gene NF1 has so far not been systematically scanned for unexpected germline mutations in individuals with sporadic pheochromocytoma.

Methods: Twenty-seven patients with bilateral adrenal and/or extraadrenal abdominal pheochromocytoma not carrying germline mutations of the genes VHL, RET, SDHB, and SDHD were selected from the European-American pheochromocytoma registry. All 57 exons and flanking intronic regions of the NF1 gene were PCR amplified using newly designed primer pairs to exclude the amplification of pseudogenes. Intragenic mutation scanning was performed using denaturing HPLC and bidirectional direct sequencing.

Results: Of the 27 apparently sporadic cases, one (4%) was found to have a pathogenic germline NF1 mutation, Leu303Arg. Clinical reevaluation of this individual, who had bilateral pheochromocytoma, revealed classic, but very mild, features of NF 1, one cutaneous neurofibroma, axillary freckling, and Lisch nodules of the iris as well as a few café-au-lait spots.

Conclusions: In the absence of germline mutations in VHL, RET, SDHD, and SDHB, patients with pheochromocytoma, especially with bilateral disease, should be checked thoroughly for clinical lesions suggestive of underlying syndromes such as the cutaneous and ophthalmological features characteristic of NF 1.
Two distinct pools of Src family tyrosine kinases regulate PDGF-induced DNA synthesis and actin dorsal ruffles
Authors: Veracini Laurence , Franco Mélanie , Boureux Anthony , Simon Valérie , Roche Serge , Benistant Christine
Published: June 2006

The mechanism by which the Src family of protein-tyrosine kinases (SFKs) regulate mitogenesis and morphological changes induced by platelet-derived growth factor (PDGF) is not well known. The cholesterol-enriched membrane microdomains, caveolae, regulate PDGF receptor signalling in fibroblasts and we examined their role in SFK functions. Here we show that caveolae disruption by membrane cholesterol depletion or expression of the dominant-negative caveolin-3 DGV mutant impaired Src mitogenic signalling including kinase activation, Myc gene induction and DNA synthesis. The impact of caveolae on SFK function was underscored by the capacity of Myc to overcome mitogenic inhibition as a result of caveolae disruption. Using biochemical fractionation we show that caveolae-enriched subcellular membranes regulate the formation of PDGF-receptor-SFK complexes. An additional pool of PDGF-activated SFKs that was insensitive to membrane cholesterol depletion was characterised in non-caveolae fractions. SFK activation outside caveolae was linked to the capacity of PDGF to induce F-actin rearrangements leading to dorsal ruffle formation. Inhibition of phospholipase C γ (PLCγ), sphingosine kinase and heterotrimeric Gi proteins implicates a PLC γ–sphingosine-1-phosphate–Gi pathway for PDGF-induced SFK activation outside caveolae and actin assembly. In addition, the cytoplasmic tyrosine kinase Abl was identified as an important effector of this signalling cascade. We conclude that PDGF may stimulate two spatially distinct pools of SFKs leading to two different biological outcomes: DNA synthesis and dorsal ruffle formation.
Ligands on the string: single-molecule AFM studies on the interaction of antibodies and substrates with the Na+-glucose co-transporter SGLT1 in living cells
Authors: Puntheeranurak Theeraporn , Wildling Linda , Gruber Hermann J. , Kinne Rolf K. H. , Hinterdorfer Peter
Published: June 2006

Atomic force microscopy (AFM) was used to probe topology, conformational changes and initial substratecarrier interactions of Na+-glucose co-transporter (SGLT1) in living cells on a single-molecule level. By scanning SGLT1-transfected Chinese hamster ovary (CHO) cells with AFM tips carrying an epitope-specific antibody directed against the extramembranous C-terminal loop 13, significant recognition events could be detected. Specificity was confirmed by the absence of events in nontransfected CHO cells and by the use of free antigen and free antibody superfusion. Thus, contrary to computer predictions on SGLT1 topology, loop 13 seems to be part of the extracellular surface of the transporter. Binding probability of the antibody decreased upon addition of phlorizin, a specific inhibitor of SGLT1, suggesting a considerable conformational change of loop 13 when the inhibitor occludes the sugar translocation pathway. Using an AFM tip carrying 1-thio-D-glucose, direct evidence could be obtained that in the presence of Na+ a sugarbinding site appears on the transporter surface. The binding site accepts the sugar residue of the glucoside phlorizin, free D-glucose, and D-galactose, but not free Lglucose and probably represents the first of several selectivity filters of the transporter. This work demonstrates the potential of AFM to study the presence and dynamics of plasma membrane transporters in intact cells on the single molecule level.
Atg9 sorting from mitochondria is impaired in early secretion and VFT-complex mutants in Saccharomyces cerevisiae
Authors: Reggiori Fulvio , Klionsky Daniel J.
Published: June 2006

In eukaryotic cells, the turnover of long-lived proteins and large cytoplasmic structures is mediated by autophagy. Components that have to be eliminated are sequestered into double-membrane vesicles called autophagosomes and delivered into the lysosome or vacuole where they are destroyed by resident hydrolases. The integral membrane protein Atg9 is essential for both autophagy and the cytoplasm-to-vacuole targeting pathway, a selective biosynthetic process in Saccharomyces cerevisiae that is mechanistically and morphologically similar to autophagy. Atg9 cycles between the pre-autophagosomal structure, the putative site of double-membrane vesicle biogenesis and mitochondria. To understand the function of Atg9, and also its trafficking mode between these two locations, we identified mutants that affect specific Atg9 transport steps. We recently reported that five Atg proteins and phosphatidylinositol-3-phosphate regulate Atg9 recycling from the pre-autophagosomal structure. Here, we describe a different category of mutants that blocks Atg9 sorting from mitochondria. All mutants have been previously shown to be required for the normal progression of both the Cvt pathway and autophagy, but their precise role in these transport routes was unknown.
Two stages of light-dependent TRPL-channel translocation in Drosophila photoreceptors
Authors: Cronin Michelle A. , Lieu Minh-Ha , Tsunoda Susan
Published: June 2006

Transient receptor potential (TRP) channels across species are expressed in sensory receptor cells, and often localized to specialized subcellular sites. In Drosophila photoreceptors, TRP-like (TRPL) channels are localized to the signaling compartment, the rhabdomere, in the dark, and undergo light-induced translocation into the cell body as a mechanism for long-term light-adaptation. We show that translocation of TRPL channels occurs in two distinct stages, first to the neighboring stalk membrane then to the basolateral membrane. In the first stage, light-induced translocation occurs within 5 minutes, whereas the second stage takes over 6 hours. The exclusive apical localization of TRPL channels in the first stage of translocation suggests that channels are released from the rhabdomere and diffuse laterally through the membrane into the adjoining stalk membrane. In the second stage, TRPL channels are localized in the basolateral membrane, implicating a different transport mechanism. Genetic analyses suggest that activation of the other light-activated TRP channel and eye-protein-kinase C (eye-PKC) are both required for the second stage of TRPL translocation in R1 to R6 photoreceptor cells, whereas only phospholipase C (PLC) is required for the first stage. Finally, we show that arrestin2 is required for the rhabdomeric localization and stability of TRPL channels.
Estimation of Reactivity by Correlation Analyses Using Ωs and ΔχB as Substituent Parameters
Authors: Isizawa Jun-ichi , Sakakibara Kazuhisa , Hirota Minoru
Published: June 2006

The ΔχB constant, defined as the difference of Bratsch’s electronegativity of a substituent group from that of CH3, was shown to serve as a versatile polar substituent constant in the multiple regression analysis using Ωs as the steric constant. Reactivities, which are usually expressed by the rate constants (k) and/or biological activities, could be expressed well in the form of a correlation equation using the steric (Ωs) and electronic (ΔχB: Bratsch’s group electronegativity) substituent parameters. As both parameters for any substituents can be obtained easily by calculations, the substituent effect on any reaction can be evaluated easily with good reliability. The correlation analyses among the Ωs, ΔχB, and the well-known Taft’s Es steric parameters showed that it must be reasonable to think that the Es parameters for the substituents containing hetero-atoms had an electronic nature to some extent as well as the steric effect.
Studies of the Selective O-Alkylation and Dealkylation of Flavonoids. XXI. A Convenient Method for Synthesizing 3,5,7-Trihydroxy-6,8-dimethoxyflavones and 5,7-Dihydroxy-3,6,8-trimethoxyflavones
Authors: Horie Tokunaru , Kitou Takeshi , Kawamura Yasuhiko , Yamashita Kazuyo
Published: June 2006

The Friedel–Crafts acetylation with boron trifluoride was studied and it was found that 1-(2,4-dihydroxy-3,5,6-trimethoxyphenyl)ethanone was conveniently synthesized from 2,3,5,6-tetramethoxyphenyl acetate in a mixture of acetic anhydride and acetic acid. 1-[2-Hydroxy-3,5,6-trimethoxy-4-(methoxymethoxy)phenyl]ethanone was cyclized to 7-hydroxy-5,6,8-trimethoxyflavone by using the Baker–Venkataraman transformation. The 7-benzyl ether of the flavone was oxidized with dimethyldioxirane and then treated with a small amount of p-toluenesulfonic acid to give 7-benzyloxy-3-hydroxy-5,6,8-trimethoxyflavone, which was converted into the methyl ether and tosylate. The 5-methoxy group in the methyl ether or tosylate was selectively cleaved with anhydrous aluminum bromide in acetonitrile under mild conditions to give the corresponding 5-hydroxyflavones and the latter compound with a 3-tosyloxy group was smoothly converted into the 3,5-dihydroxyflavone by hydrolysis with potassium carbonate in methanol. The hydrogenolysis of the 7-benzyloxy-3,5-dihydroxyflavone and its 3-methyl ether afforded quantitatively 3,5,7-trihydroxy-6,8-dimethoxyflavone and its 3-methyl ether. The process was suitable as a general method for synthesizing 3,5,7-trihydroxy-6,8-dimethoxyflavones and their 3-methyl ethers and the six flavones were synthesized for the clarification of their 1H and 13C NMR, MS, and UV spectral properties.
Mass-Spectrometric Study on Ion–Molecule Reactions of CF3+ with Monosubstituted Benzenes Carrying a Carbonyl Group at Near-Thermal Energies
Authors: Tsuji Masaharu , Aizawa Masato , Nishimura Yukio
Published: June 2006

The gas-phase ion–molecule reactions of CF3+ with five monosubstituted benzenes carrying a carbonyl group (PhCOX: X = H, CH3, C2H5, OCH3, OC2H5) have been studied at near-thermal energies using an ion-beam apparatus. The major product channel for PhCHO, PhCOCH3, and PhCOOCH3 is electrophilic addition to the O-atom leading to initial adduct ions, which are 80.3—95.0% of the total product ions. Although no initial adduct ions are observed for PhCOC2H5 and PhCOOC2H5, major product ions are formed by electrophilic addition to the O-atom followed by dissociation and molecular eliminations. The reaction mechanism is discussed based on product ion distributions and semi-empirical calculations of the energies of intermediates and products. The results obtained are compared with reported ion-cyclotron-resonance data for aliphatic carbonyl compounds.
Activation of C–O and C–N Bonds in Allylic Alcohols and Amines by Palladium Complexes Promoted by CO2. Synthetic Applications to Allylation of Nucleophiles, Carbonylation, and Allylamine Disproportionation
Authors: Sakamoto Masato , Shimizu Isao , Yamamoto Akio
Published: June 2006

The direct activation of the C–O bonds in allylic alcohols catalyzed by palladium complexes has been accelerated by carrying out the reactions under CO2. On reaction with diethylamine, allyl alcohol can be converted into N,N-diethylallylamine in the presence of palladium complexes at room temperature under normal pressure of carbon dioxide. Allylation of various carbon nucleophiles such as β-keto esters and β-diketones can be achieved by using allylic alcohols directly in the presence of palladium complexes and CO2. Direct carbonylation of allylic alcohols into unsaturated carboxylic acids can be catalyzed by palladium complexes under the pressure of CO and CO2. Disproportionation of diallylamine into triallylamine and allylamine is also catalyzed by palladium complexes in the presence of CO2. On the basis of studies on the behavior of η3-allylpalladium hydrogencarbonate complexes with the nucleophiles, mechanisms are proposed to account for the palladium-catalyzed allylation processes influenced by CO2.
NAD(P)+–NAD(P)H Models. 86. Nonsteric Stereochemistry in Hydride-Transfer to Sulfinylpyridinium Ion
Authors: Ohno Atsuyoshi , Yamazaki Norimasa , Okamura Mutsuo , Kawai Yasushi , Tsutsumi Akihiro , Mikata Yuji , Fujii Masayuki
Published: June 2006

The molecular structure of an enantiomer of nicotinamide coenzyme analog 1 has been determined by X-ray crystallography with the absolute configuration being established by the anomalous dispersion effects of all non-hydrogen atoms: (+)-1 exhibits (S)-form sticking the sulfinyl S–O out of the re face. The stereochemistry of the hydride-transfer reaction between the chiral coenzyme analogs, 1 and MenPNPH, was studied. The hydride from (S)- or (R)-MenPNPH, respectively, transfers to (S)- or (R)-1, affording the dihydropyridine compound syn-2 predominantly: That is, the reaction takes place in the face occupied by the sulfinyl oxygen. On the other hand, the transfer to (R)- or (S)-1 mainly takes place so as to afford anti-2. It has been deduced that (S)-1 reacts with (S)-MenPNPH more than twice as fast as (R)-1 does or vice versa. It has also been elucidated that the amide oxygen in MenPNPH points to 1 exclusively at the transition state of the reaction, regardless the configuration of the reagents. The intermolecular arrangement at the transition state of the reaction is discussed.
Peptide Synthesis in Aqueous Solution. V. Properties and Reactivities of (p-Hydroxyphenyl)benzylmethylsulfonium Salts for Direct Benzyl Esterification of N-Acylpeptides
Authors: Nakata Takashi , Nakatani Masaru , Takahashi Masatoshi , Okai Jiro , Kawaoka Yoshiaki , Kouge Katsushige , Okai Hideo
Published: June 2006

Some (p-hydroxyphenyl)benzylmethylsulfonium salts were prepared. These compounds generated a benzyl cation and converted not only N-acylamino acids but also N-acylpeptides into their corresponding benzyl esters without causing the racemization.
Rh(I)-Catalyzed Dehydrogenative Silylation of Divinylsilanes with Dimethylphenylsilane
Authors: Kawanami Yukio , Yamamoto Keiji
Published: June 2006

Rh(I)-catalyzed dehydrogenative silylation was selectively carried out by using divinylsilanes and half an equimolar amount of trialkylsilanes under ambient conditions to give 1,2-disilylethene and ethylvinylsilane derivatives in equimolar amounts. The mechanistic aspects for the dehydrogenative silylation were discussed in terms of the consecutive migratory insertions of the alkene moiety into both Rh–Si and Rh–H bonds which are formed by an oxidative addition of the hydrosilane to the Rh(I) catalyst precursor.
Chromium-Binding Ability of Tannin in Water-Extracts from Withered Oak Leaves
Authors: Arakawa Hirohumi , Watanabe Norimoto
Published: June 2006

Reaction mixtures containing constant amounts of water-extract from withered oak leaves and various concentrations of potassium chromate were incubated, and each reaction mixture was fractionated by a Sephadex G-25 column. The concentrations of the Cr-tannin obtained in the fractions were determined. Then the Cr-binding ability of the tannin was examined by apparent stability constants and Cr-complexing capacities, following construction of a Scatchard plot which adopts a two-site model. The tannin was shown to have two-classes of Cr-binding sites. Based on the Cr-complexing capacities, 1 mg tannin was shown to bind about 0.5 mg of reduced Cr. Moreover, functional groups contributing to the complexation with Cr were investigated by FTIR and pH titration. The relationship between the Cr-complexing ligans in the two sites and the functional groups in the tannin was also investigated. Finally, Cr ion species which emerged during the reaction between chromate and the tannin were determined by EPR. The spectra showed a sharp signal attributable to Cr(V) and a broad one assignable to Cr(III). Thus, it can be speculated that the tannin most probably forms a final Cr(III)–tannin via Cr(V) species.
Mechanism of Chemiluminescence Reaction between Hypobromite and Ammonia or Urea
Authors: Hu Xincheng , Takenaka Norimichi , Kitano Masaru , Bandow Hiroshi , Maeda Yasuaki
Published: June 2006

The reaction kinetics, the chemiluminescence spectra, the products, and the lifetimes of emission species for the chemiluminescence reaction between hypobromite and ammonia or urea in an alkaline aqueous solution were investigated. Results show that the reaction mechanism for ammonia chemiluminescence is different from that for urea. The reaction of ammonia and hypobromite produces NO2 in the gaseous phase and NO2− in solution; however, the reaction of urea and hypobromite does not. For the reaction of ammonia and hypobromite, chemiluminescence intensity obeys 1.5 order kinetics for hypobromite concentration when ammonia is in excess, but the reaction of urea and hypobromite obeys second order kinetics for hypobromite when urea is in excess. The spectrum of the chemiluminescence from the ammonia and urea with hypobromite shows a maximum intensity at 710, and at 510 nm, respectively. The chemiluminescence lifetimes of the emission species were 0.056 and 0.092 s for the reaction of ammonia and the reaction of urea, respectively. The chemiluminescence species of the reaction between hypobromite and ammonia seems to be excited NO2, that for urea seems to be excited N2.
Insertion vs. Abstraction in the Reactions of NH(a1Δ, v = 0, 1) with H2 and D2
Authors: Yunoki Kumi , Tezaki Atsumu , Yokoyama Keiichi , Matsui Hiroyuki
Published: June 2006

Gas-phase reactions of NH(a1Δ, v = 0,1) + H2 (1) and NH(a1Δ, v = 0,1) + D2 (2) were studied in the photolysis of HNCO/H2 (or D2) mixtures. NH(a1Δ) and product H (D) atom were detected by UV and vacuum-UV laser-induced fluorescence. The observed rate constants at room temperature (295 ± 2K) and activation energies in the range of 295 — 407 K were;

in units of 10−12 cm3 molecule−1 s−1 and kJ mol−1. The product branching ratio in reaction 2 was determined to be [D]/[H] = 3.2 ± 0.76, in which no temperature dependence was indicated. These results are consistent with insertion mechanism having a loose entrance transition state structure, which is suggested by ab initio CI calculations. In contrast, the contribution of direct abstraction channel is supposed to be negligibly small.
Anaerobic Solid-Phase Thermal Configurational Transformations of Cobalt(II) Complexes
Authors: El-Behairy Mostafa
Published: June 2006

New examples of thermal tetrahedral-to-octahedral transformation were discovered and studied in the thermal reactions of disodium tetrakis(aryloxo)cobaltate(II) complexes, of the formula Na2[Co(OAr)4(thf)m]·nthf (OAr = o-chloro-, o-bromo-, m-chloro-, p-bromo-, 2,4-dichloro-, 2,4-dimethyl- or 2,6-dichlorophenoxo; m = 2 for all complexes except for 2,4-dimethylphenoxo complex where m = 0; thf: tetrahydrofuran; n = 1—3), in the solid phase. With one exception, the original complexes were all violet colored and have octahedral configurations. The exception is Na2[Co(2,4-Me2C6H3O)4]·thf, which has an intense blue color and its electronic and magnetic data are characteristic of tetrahedral cobalt(II). The aryloxo complexes of 2,6-dichloro-, m-chloro-, and p-bromophenoxo show a two-step thermochromism, violet → blue → rose, upon heating. These steps correspond to structural changes to tetrahedral thf-free complexes and then to aryloxo bridged polymers with octahedral cobalt(II) ions, respectively. o-Chloro- and o-bromophenoxo complexes underwent only thermal desolvation–polymerization, which occurs in one step, changing directly into the rose aryloxo-bridged polymers. 2,4-Dichlorophenoxo complex shows only one-step thermochromism, violet → blue, thus changing from the octahedral to tetrahedral configuration. The remainder complex, of 2,4-dimethylphenoxo, does not show any color changes and retained its tetrahedral configuration until it decomposed. The reverse changes of the thermal products to the original complexes proceed on standing under dry thf atmosphere, for some hours or days.
Kinetics and Thermodynamics of the Racemization of Tris(l-valinato)chromium(III) Complexes in N,N-Dimethylformamide
Authors: Nakata Ryuji , Yano Masatoshi , Ochi Yukari , Hatanaka Naomi , Oki Hisaya
Published: June 2006

Racemization between fac-Λ-(+)546- and fac-Δ-(−)546-[Cr(val)3] (1 and 2) was studied in N,N-dimethylformamide (DMF). These complexes were preferentially converted into bis-type complexes, Λ-(+)546- and Δ-(−)546-[Cr(val)2(val-N)DMF] (4 and 3), and an equilibrium comprising these four species was established. In order to determine the equilibrium constants, rate constants, and activation parameters in a proposed square-network reaction system, the mole fractions of four species with time in reacting solutions at 40, 50, and 60 °C were determined by liquid chromatography. The reaction processes are discussed based on the obtained values.
Synthesis and Structural Characterization of Praseodymium(III) and Neodymium(III) Complexes of Tripodal Tris[2-(salicylideneamino)ethyl]amine
Authors: Kanesato Masatoshi , Yokoyama Toshiro , Itabashi Osamu , Suzuki Toshishige M , Shiro Motoo
Published: June 2006

The preparation and characterization of praseodymium(III) and neodymium(III) complexes of heptadentate (N4O3) ligand trensal, tris[2-(salicylideneamino)ethyl]amine (H3L1), have been studied. These complexes (PrL1 and NdL1) were prepared by the reaction of the praseodymium(III) or neodymium(III) complex of 1,9-bis(2-aminoethyl)-1,4,6,9,12,14-hexaazacyclohexadecane with salicylaldehyde in acetonitrile. Alternatively, the reaction of tris(2-aminoethyl)amine and salicylaldehyde in the presence of praseodymium(III) or neodymium(III) salt in acetonitrile also gave praseodymium(III) and neodymium(III) complexes of trensal. The molecular structures of PrL1 and NdL1 were determined by X-ray structural analysis; these are rare examples of lanthanide heptadentate complexes in which the metal ions are coordinated by the four nitrogen atoms and the three oxygen atoms. The crystals of Pr(C27H27N4O3)·0.5CH3CN and Nd(C27H27N4O3)·0.5CH3CN are both trigonal, space group , a = 13.713(2), c = 8.093(3) Å, U = 1318.0(7) Å3, Z = 2 for [PrL1]·0.5CH3CN, and a = 13.724(3), c = 8.067(3) Å, U = 1315.8(7) Å3, Z = 2 for [NdL1]·0.5CH3CN. The structures were solved by heavy-atom Patterson methods and expanded using Fourier techniques; they were then refined by full-matrix least-squares procedures to R = 0.033 and Rw = 0.043 for 1547 observed reflections with I ≥ 3σ(I), R = 0.028 and Rw = 0.039 for 1923 observed reflections with I ≥ 3σ(I) for [PrL1]·0.5CH3CN and [NdL1]·0.5CH3CN, respectively. The individual metal ions and the apical nitrogen atoms lie on a 3-fold axis in each crystal; the molecules possess a C3 molecular symmetry.
New Xenia Diterpenoids from a Soft Coral, Xenia Species Containing Fatty Acyl Side Chains
Authors: Iwagawa Tetsuo , Amano Yasuhisa , Nakatani Munehiro , Hase Tsunao
Published: June 2006

Seven new diterpenoids with an opened A-ring containing an aliphatic acid, called azamilides A—G (1—7), have been isolated from an acetone extract of Xenia sp. and their structures elucidated on the basis of spectroscopic analysis.
Mass-Spectrometric Study on Ion-Molecule Reactions of CF3+ with Furan and Thiophene at Near-Thermal Energies
Authors: Aizawa Masato , Tsuji Masaharu , Nishimura Yukio
Published: June 2006

The branching ratios of product ions for the reactions of CF3+ with furan and thiophene were determined by using an ion-beam apparatus. The main reaction channels proceed via α- and β-trifluoromethylated intermediates (C-adducts), followed by HF elimination, CO elimination, and CO + HF elimination for furan, and followed by HF elimination for thiophene. Semiempirical MNDO calculations of heats of formation of various intermediates and products were carried out to explore possible mechanisms. It was concluded that the CO and CO + HF eliminations for furan occur through a cleavage of a C–O skeletal bond of the C-adducts. The lack of CO and CO + HF elimination channels for thiophene was explained by the fact that the ring-opening and ring-contraction channels are energetically closed.
Alkylation of 1-[N-(Hydroxymethyl)-N-methylamino]-4-quinolones. An Improved Preparation of Intermediates for Novel Potent Tricyclic Quinolone Antibacterial Agents
Authors: Barrett David , Sasaki Hiroshi , Kinoshita Takayoshi , Tsutsumi Hideo , Sakane Kazuo
Published: June 2006

A new and improved method for the preparation of the key cyclization precursors for novel pyrido[3,2,1-ij]cinnoline antibacterial agents that avoids the use of di-t-butyl methylenemalonate is described. The key process is the alkylation of 1-[N-(hydroxymethyl)-N-methylamino]-4-quinolones with di-t-butyl malonate via the intermediate chloromethyl derivatives. Unexpectedly, this process produced labile pyrazolo[1,5-a]quinoline derivatives that were subsequently shown to undergo ring opening and cyclization to C8 to produce the pyrido[3,2,1-ij]cinnoline key intermediates.
cine-Substitution of 1-Methyl-3,6,8-trinitro-2-quinolone
Authors: Nishiwaki Nagatoshi , Tanaka Aya , Uchida Mitsue , Tohda Yasuo , Ariga Masahiro
Published: June 2006

cine-Substitution of 1-methyl-3,6,8-trinitro-2-quinolone by 1,3-dicarbonyl compounds in the presence of NEt3 occurred efficiently, affording 4-functionalized 6,8-dinitro-2-quinolone derivatives. The addition intermediate was isolated in the reaction with CH2(CO2Et)2 and EtONa. Conversion of the isolated intermediate into the cine-substituted product was performed. These results indicate that the present cine-substitution proceeds by the addition-elimination mechanism.
Synthesis of [Hexafluorovalyl1,1′]gramicidin S
Authors: Arai Toru , Imachi Takashi , Kato Tamaki , Ogawa H Iyehara , Fujimoto Tsutomu , Nishino Norikazu
Published: June 2006

[Hexafluorovalyl1,1′]gramicidin S (8), in which two valine residues in the natural gramicidin S were replaced by l-hexafluorovaline (Hfv) residues, was synthesized by the solid-phase-synthesis and cyclization-cleavage method on benzophenone oxime resin. Though the racemic hexafluorovaline derivative was employed for the peptide synthesis, the desired product was isolated in moderate yield, probably reflecting the stable cyclic structure of 8. CD and 1H NMR spectra indicated that the conformation of 8 is similar to that of gramicidin S. The two β-turn structure and antiparallel β-sheet structure with four intramolecular hydrogen bondings were maintained in spite of introducing the hexafluorovaline residues. The dye-release experiment from lecithin vesicle and antimacrobial activity assay also indicated that 8 showed membrane-disturbing activity like gramicidin S, although the activity of 8 was somewhat weaker than gramicidin S.
Synthesis of Macrocyclic Amides and Their Intermediate 2 : 1 and 3 : 2 Reaction Compounds from Diethyl Oxalate and Ethereal Oxygen-Containing Diamines
Authors: Fukada Naoaki , Ohtsu Tadashi , Miwa Masamichi , Mashino Masayuki , Takeda Yasuyuki
Published: June 2006

The reaction of diethyl oxalate with ethereal oxygen-containing diamines under high-dilution conditions gave 2 : 2 reaction products, 22-, 28-, and 34-membered macrocyclic amides in good yields. From the 2 : 1-mixed reaction between diethyl oxalate and the diamines, acyclic 2 : 1 and 3 : 2 reaction products were isolated at a ratio of ca. 9 : 1. The intermediate 2 : 1 and 3 : 2 reaction products led to the 2 : 2 reaction products mentioned above and the 3 : 3 reaction products, 33-, 42-, and 51-membered macrocyclic amides, respectively, upon reaction with additional corresponding diamines. Also, other macrocyclic amides were synthesized by combining the 2 : 1 reaction products and diamines.
An Acylative C–C Single-Bond Cleavage and a Self-Cyclization of Ethyl 2-(Trimethylsilylmethyl)penta-2,4-dienoate or Its Free Acid under Ritter Condition
Authors: Kuroda Chiaki , Mitsumata Naoko , Tang Chen Ying
Published: June 2006

An acylative C(3)–C(4)-bond cleavage of ethyl 4,5-disubstituted 2-(trimethylsilylmethyl)penta-2,4-dienoate occurred to give an ethyl 2-(2-oxoalkyl)acrylate by treatment with trifluoromethanesulfonic acid in nitriles. A self-cyclization also occurred to give a 5,5-disubstituted 3-methylenetetrahydrofuran-2-one when the reactions were carried out in bulky nitriles. Only self-cyclization proceeded when the corresponding 4,5-disubstituted 2-(trimethylsilylmethyl)penta-2,4-dienoic acid was treated in acetonitrile. The reaction mechanism is described.
Preparation and Properties of Monovalent Anion Permselective Anion Exchange Membranes
Authors: Takata Kuniaki , Hanada Fumio , Kagiyama Yasuhiro , Sata Toshikatu
Published: June 2006

In order to prepare a monovalent permselective anion exchange membrane, the surface of a precursor membrane, which was prepared from a membranous copolymer of chloromethylstyrene (CMS) and divinylbenzene (DVB) in the presence of poly(vinyl chloride), was treated with various amino compounds; the chloromethylphenyl groups in the membrane were then reacted with trimethylamine so as to introduce (trimethylammoniomethyl)phenyl groups. The anion exchange membranes which were modified with tetraethylenepentamine and 4-vinylpyridine showed a chloride anion permselectivity versus that of a sulfate one in electrodialysis. It was thought that the reaction between these amines and the chloromethylphenyl groups formed a higher crosslinking structure on the surface of the membrane.
Kinetics of the Photobromination of Fluoroethane. Estimate of the C–H Bond Dissociation Energies and the Heats of Formation of the CH3CHF and CH2CH2F Radicals
Authors: Miyokawa Kikuo , Ozaki Shigeko , Yano Takayuki
Published: June 2006

The gas-phase photobromination of fluoroethane was investigated in the temperature range 80—150 °C in both the presence and absence of chloroethane as an external competitor. The rate constant for α-hydrogen abstraction in CH3CH2F was redetermined relative to that in CH3CH2Cl, and the abstraction of β-hydrogen was measured in the internal competition. The relative rates were combined with the known rate parameters for the bromination of C2H6 to obtain the absolute rate constants (cm3 mol−1 s−1): k(α) = (6.50 ± 3.58) × 1012 exp [−(10360 ± 370)/RT] and k(β) = (3.42 ± 1.95) × 1012 exp [−(12950 ± 390)/RT].

Using a justifiable approximation concerning the magnitude of the activation-energy difference for the reverse reactions between any two competitors with similar complexity the following thermochemical quantities (kcal mol−1) have been derived: ΔH°f(CH3CHF) = −16.8 ± 2, ΔH°f(CH2CH2F) = −14.2 ± 2, D°(CH3CHF–H) = 98.2 ± 2, D°(CH2FCH2–H) = 100.8 ± 2, and D°(CH2CH2–F) = 45.6 ± 2. The influence of halogen substitution on the rate parameters of hydrogen abstraction from monohaloethanes is discussed.
Crystal Structures and Magnetic Properties of MCl42− (M = Mn(II) and Co(II)) Salts of m- and p-N-Methylpyridinium Nitronyl Nitroxides
Authors: Yamaguchi Akira , Okuno Tsunehisa , Awaga Kunio
Published: June 2006

Organic radical cations, 4,4,5,5-tetramethyl-2-(1-methyl-3 or 4-pyridinio)-3-oxide-4,5-dihydro-1H-1-imidazolyloxyl (or, m- and p-N-methylpyridinium nitronyl nitroxides, abbreviated as m- and p-MPYNN+, respectively), were found to crystallize with magnetic counter anions, MCl42− (M = Mn2+ (S = 5/2) and Co2+ (S = 3/2)), although the MnCl42− salts were rather air-sensitive. X-Ray full-crystal analyses were carried out on the stable CoCl42− salts. The structure of (m-MPYNN+)2CoCl42− crystallizes in the monoclinicP21/c space group, while that of (p-MPYNN+)2CoCl42− belongs to the triclinic space group. Although (m-MPYNN+)2MnCl42− and (p-MPYNN+)2MnCl42− were not stable enough for an X-ray full data collection, they were indicated to be isostructural to the corresponding CoCl42− salts, respectively, by their diffractions of 20 > θ > 25°. Variable-temperature magnetic susceptibility measurements reveal a clear contrast between the (m-MPYNN+)2MCl42− and (p-MPYNN+)2MCl42− salts. The two (m-MPYNN+)2MCl42− salts exhibit a ferromagnetic behavior independently of MCl42−, which is attributable to a m-MPYNN+ dimer. However, the magnetic properties of two (p-MPYNN+)2MCl42− salts are strongly dependent on the MCl42− anion: (p-MPYNN+)2MnCl42− exhibits an antiferromagnetic interaction in opposition to a ferromagnetic one in (p-MPYNN+)CoCl42−. The magnetic difference between them can be qualitatively understood in terms of a charge-transfer interaction between MCl42− and p-MPYNN+, in which the difference in the electronic structure between the Mn2+ and Co2+ ions is reflected.
Crystalline Polymorphism and Phase Transition Behavior of Mesogenic 4-Heptyloxy-4′-cyanobiphenyl (7OCB)
Authors: Hori Kayako , Koma Yoshiko , Kurosaki Minako , Itoh Koichi , Uekusa Hidehiro , Takenaka Yasuyuki , Ohashi Yuji
Published: June 2006

Four different solid phases were found for the title compound: square-plate and needle crystals, which are metastable, a solid found in a collapsed plate crystal and the most stable crystalline phase found in a commercially available powder specimen. The phase transition behavior of each solid to the nematic phase was investigated by DSC. The phase relations are proposed in terms of Gibbs energy and temperature diagram. The structure of the plate crystal has been determined at 243 K. The crystal has a distinct smectic-like structure composed of bilayers. The CN groups are closely arranged between antiparallel molecules within a bilayer, resulting in infinite networks with the C–N distances; 3.41—3.64 Å.
Lattice-Dynamical Study of the Abnormally Short Bond-Length in trans-Stilbene Molecules in a Crystal
Authors: Saito Kazuya , Ikemoto Isao
Published: June 2006

Lattice-dynamics calculations have been made on crystalline trans-stilbene under an atom–atom potential approximation, using both flexible and rigid molecular models in order to clarify the existence of the molecular motion suggested for explaining the abnormal bond-length of the central C=C bond. The intramolecular twisting of the benzene rings strongly couples with the overall rotation of the molecule in some manner, including the suggested manner. The coupled modes form phonon branches and show little dispersion.
Investigation of Single-Vibronic-Level Fluorescence Lifetimes of Jet-Cooled S1trans-Stilbene above the Isomerization Barrier
Authors: Tahara Tahei , Hamaguchi Hiro-o
Published: June 2006

The fluorescence lifetimes of jet-cooled trans-stilbene were measured for twenty eight S1 vibronic levels in the 1300—1700 cm−1 region above the 0–0 transition. All fluorescence decay curves were well fitted to single exponential functions in the 0—3 ns time region. It was found that the fluorescence lifetime decreases monotonically with the increase of the excess vibrational energy. No anomalous lifetime dependence on the vibronic level was observed. The (time-integrated) dispersed fluorescence from the corresponding vibronic levels was also measured. The excitation of all twenty eight levels gave indistinguishable fluorescence spectra exhibiting only broad features, indicating that the IVR rate is much larger than the radiative decay rate regardless of the fundamental, overtone or combination levels. No direct evidence supporting the existence of a mode-selective isomerization channel was obtained.
Structural Effects in NMR Spectroscopy of Vinylic Compound 1. Investigation of Intramolecular Specific Interactions C–H···N in Hetaryl Vinyl Ethers by 1H, 13C, 15N, and 17O NMR Spectroscopies and Quantum-Chemical Calculations
Authors: Afonin Andrei V , Vashchenko Alexander V , Fujiwara Hideaki
Published: June 2006

The hydrogen bond-like intramolecular specific interactions between the α-hydrogen of the vinyl group and endo-cyclic nitrogen are discovered in the hetaryl vinyl ethers, having the vinyloxyl group neighboring to the endocyclic nitrogen by the 1H and 13C NMR data. It is confirmed by AM1 calculations. The intramolecular specific interaction results to the downfield shift of the α-proton signal by 1 ppm, α-carbon signal by 4—5 ppm, the increase of their one-bond coupling constant by 6—7 Hz, and upfield shift of nitrogen by 17—20 ppm, as it was shown by the regression and dispersion analysis of 1H, 13C, and 15N parameters of wide series of aryl and hetaryl vinyl ethers. The cluster analysis of the spectral data indicates the anomaly of common combination of vinyloxyl group parameters in ethers, possessing the intramolecular specific interaction in comparison with ethers which have no such interaction. The factor analysis of spectral parameters shows that influence of specific interaction on the α-proton and α-carbon chemical shifts as well as their one-bond coupling constant prevails over other structural and electronic effects. In accordance with the AM1 calculation, the hetaryl vinyl ethers possessing the intramolecular specific interaction are more planar that is confirmed by 13C and 17O NMR data.
A New-Type Adsorption Isotherm of CO on Transition Metal Surfaces with Adsorption-Assisted Processes
Authors: Tamaru Kenzi
Published: June 2006

A new adsorption isotherm is proposed, taking the adsorption-assisted desorption into consideration for the first time. The new adsorption isotherm is in reasonable agreement with the experimental data.
Kinetic Analyses of an Electrochemically-Induced Reaction through a Generation-Collection Mode of Twin-Microband Electrodes
Authors: Nakatani Kiyoharu , Terui Norifumi , Kitamura Noboru
Published: June 2006

Kinetic analyses of a sulfonation reaction between electrochemically-generated diethyl(4-imino-3-methyl-2,5-cyclohexylidene)ammonium salt (quinone diimine derivative (QDI) and SO32− in water have been performed by a generation-collection mode of twin-microband electrodes. The collection efficiency of QDI (φ), defined as the ratio of the current at a generator to that at a collector, was dependent on the interelectrode distance and the SO32− concentration. The rate constant of the sulfonation reaction was determined by both a two-dimentional digital simulation of the concentration gradient of QDI and kinetic analyses of the observed φ values.
Open Source Software User Communities: A Study of Participation in Linux User Groups
Authors: Bagozzi Richard P. , Dholakia Utpal M.
Published: June 2006

We conceptualize participation in Linux user groups (LUGs) in terms of group-referent intentional actions and investigate cognitive (attitudes, perceived behavioral control, identification with the open source movement), affective (positive and negative anticipated emotions), and social (social identity) determinants of participation and its consequences on Linux-related behaviors of users. This survey-based study, conducted with 402 active LUG members representing 191 different LUGs from 23 countries and employing structural equation modeling methodology, supports the proposed model. Furthermore, we find that the Linux user’s experience level moderates the extent of the LUG’s social influence and its impact on the user’s participation. We conclude with a consideration of the managerial and research implications of the study’s findings.
Tipranavir: A Protease Inhibitor for HIV Salvage Therapy
Authors: Dong Betty J , Cocohoba Jennifer M
Published: June 2006

Objective:

TO review the efficacy, safety, pharmacology, virology, pharmacokinetics, and resistance of the nonpeptidic protease inhibitor (PI) tipranavir.

Data Sources and Study Selection:

A PubMed search (1966–February 2006) was conducted using the key words tipranavir or PNU-140690, with the limitation of English-language reports. Pharmacokinetic and randomized clinical trials originating from major HIV conferences, such as the Conference on Retroviruses and Opportunistic Infections, International AIDS Society, European AIDS Conference, and Interscience Conference on Antimicrobial Agents and Chemotherapy, published only in abstract form, from 2000 to February 2006, were reviewed for relevance and included in this review.

Data Synthesis:

Phase III studies have shown that tipranavir is effective in the treatment of PI-resistant HIV compared with other PI-containing regimens. Adverse effects associated with tipranavir/ritonavir therapy include gastrointestinal reactions, hepatotoxicity, and elevations in cholesterol and triglyceride levels. Resistance data suggest that tipranavir/ritonavir should be reserved for salvage therapy in antiretroviral-experienced patients who have previously failed standard PI therapies. The potential for hepatotoxicity and drug interactions and the expense of tipranavir due to required ritonavir boosting may limit its widespread use.

Conclusions:

Tipranavir/ritonavir is an essential addition to the antiretroviral armamentarium for HIV-infected patients with limited treatment options.
Injuries in Norwegian Ski Resorts 2002 – 2004
Authors: Ekeland A , Rødven A
Published: June 2006

A central ski patrol-based registration of skiing and boarding injuries was performed by the Norwegian Ski Lift Association during the winter seasons 2002/2003 and 2003/2004. Totals of 7252 injured skiers/boarders and 4.884 million skier/boarder days were recorded during the two seasons, giving an injury rate of 1.5 injured per 1000 skier/boarder days. Most of the injuries occurred during alpine skiing (49 %) and snowboarding (43 %), whereas telemark skiing and skiboarding each accounted for 4 % of the injuries. Wrist injuries were common among injured snowboarders (28 %) compared to only 6 % for skiboarders and 4 % each for alpine and telemark skiers (P<0.001). The knee was the main injury location in alpine skiers (25 %) compared to 19 % among skiboarders, 12 % among telemarkers, and only 7 % among snowboarders (P<0.001), but the percentage of knee injuries was almost twice as high for females compared to males, both in skiers and snowboarders (P<0.001). As percent of all injuries, injured snowboarders suffered more fractures (35 %) than skiboarders (30 %), telemark (24 %) and alpine skiers (22 %) (P<0.001), but fracture of the lower leg was uncommon among snowboarders (1 %) and telemarkers (2 %) compared to alpine skiers (7 %) and skiboarders (15 %) (P<0.001). Lower leg fractures accounted for 4 % of the injured alpine skiers 20 years and older and adolescents aged 13–19 years compared to 15 % for children 12 years and younger (P<0.001). Nineteen percent of the skiers/boarders were injured in snowboarder parks, and these injuries were more severe than those occurring at other locations. In conclusion, injured alpine skiers were most prone to knee injuries, and skiboarders to lower leg fractures. This fracture was still a common injury for children in these two disciplines. Injured snowboarders were most prone to suffer wrist injuries. The percentage of knee injuries among females was almost twice that of males both in skiers and snowboarders. Injuries sustained in snowboarder parks were more severe than other injuries on the slope.
Used Oil Derived Fuel Utilization for the Production of Portland Cement
Authors: Ayala NI
Published: June 2006

The cement industry can assume a very important role in achieving a sustainable future. As the global population rises, the general public is placing an increased pressure on the conservation of essential natural resources such as land and nonrenewable energy sources with a need for more socially and environmentally sustainable development initiatives. Cement is one of the most important components of the infrastructure needed to support that sustainable development. The cement industry has been globally linked to those industries with extensive use of nonrenewable natural resources and with a high energy demand. It is well known that a cement plant needs between 80 kg to 150 kg of fuel and at least 100 kWh of electricity to produce one ton of cement. With such high energy demand, the cement industry has been searching and implementing several alternative fuel initiatives to increase energy efficiency and lower fuel and energy costs with many consequential environmental benefits. One of those clearly available fuel alternatives is used motor oil. In this study, the characteristics of used oil are measured through a detailed evaluation of fuel based on heating value, viscosity, and water content. The environmental benefits are measured through the evaluation of CO2 emission reduction and dioxin/furan stack testing.
Development of Pavement Smoothness Index Relationship
Authors: Chen J-S , Huang C-C
Published: June 2006

In its pursuit for providing smooth pavements, the Directorate General of Highways in Taiwan is developing and implementing ride quality specification as part of the construction assurance program. The straightedge and the profiler were used to measure pavement smoothness on 561 test sections. Probability distribution analysis showed that measurements of pavement smoothness of both devices follow the normal distribution. Smoothness specifications for construction quality control were developed for straightedge and profiler, respectively. The full-pay range is 1.36 to 2.45 mm and 2.16 to 3.65 m/km for straightedge and profiler, respectively. The smoothness relationship between straightedge and profiler was developed.