bluuebunny/crossref_metadata_2025 huggingface dataset:
Sortilin, SorCS1b, and SorLA Vps10p sorting receptors, are novel γ-secretase substrates
Authors: Nyborg Andrew C , Ladd Thomas B , Zwizinski Craig W , Lah James J , Golde Todd E
Published: June 2006

Background

The mammalian Vps10p sorting receptor family is a group of 5 type I membrane homologs (Sortilin, SorLA, and SorCS1-3). These receptors bind various cargo proteins via their luminal Vps10p domains and have been shown to mediate a variety of intracellular sorting and trafficking functions. These proteins are highly expressed in the brain. SorLA has been shown to be down regulated in Alzheimer's disease brains, interact with ApoE, and modulate Aβ production. Sortilin has been shown to be part of proNGF mediated death signaling that results from a complex of Sortilin, p75NTRand proNGF. We have investigated and provide evidence for γ-secretase cleavage of this family of proteins.

Results

We provide evidence that these receptors are substrates for presenilin dependent γ-secretase cleavage. γ-Secretase cleavage of these sorting receptors is inhibited by γ-secretase inhibitors and does not occur in PS1/PS2 knockout cells. Like most γ-secretase substrates, we find that ectodomain shedding precedes γ-secretase cleavage. The ectodomain cleavage is inhibited by a metalloprotease inhibitor and activated by PMA suggesting that it is mediated by an α-secretase like cleavage.

Conclusion

These data indicate that the α- and γ-secretase cleavages of the mammalian Vps10p sorting receptors occur in a fashion analogous to other known γ-secretase substrates, and could possibly regulate the biological functions of these proteins.
Genetic regulators of myelopoiesis and leukemic signaling identified by gene profiling and linear modeling
Authors: Brown Anna L , Wilkinson Christopher R , Waterman Scott R , Kok Chung H , Salerno Diana G , Diakiw Sonya M , Reynolds Brenton , Scott Hamish S , Tsykin Anna , Glonek Gary F , Goodall Gregory J , Solomon Patty J , Gonda Thomas J , D’Andrea Richard J
Published: June 2006

Mechanisms controlling the balance between proliferation and self-renewal versus growth suppression and differentiation during normal and leukemic myelopoiesis are not understood. We have used the bi-potent FDB1 myeloid cell line model, which is responsive to myelopoietic cytokines and activated mutants of the granulocyte macrophage-colony stimulating factor (GM-CSF) receptor, having differential signaling and leukemogenic activity. This model is suited to large-scale gene-profiling, and we have used a factorial time-course design to generate a substantial and powerful data set. Linear modeling was used to identify gene-expression changes associated with continued proliferation, differentiation, or leukemic receptor signaling. We focused on the changing transcription factor profile, defined a set of novel genes with potential to regulate myeloid growth and differentiation, and demonstrated that the FDB1 cell line model is responsive to forced expression of oncogenes identified in this study. We also identified gene-expression changes associated specifically with the leukemic GM-CSF receptor mutant, V449E. Signaling from this receptor mutant down-regulates CCAAT/enhancer-binding protein α (C/EBPα) target genes and generates changes characteristic of a specific acute myeloid leukemia signature, defined previously by gene-expression profiling and associated with C/EBPα mutations.
The central role of adrenomedullin in host defense
Authors: Zudaire Enrique , Portal-Núñez Sergio , Cuttitta Frank
Published: June 2006

Thirteen years after the isolation of adrenomedullin (AM) from a human pheochromocytoma, the literature is awash with reports describing its implication in countless physiological and disease mechanisms ranging from vasodilatation to cancer promotion. A growing body of evidence illustrates AM as a pivotal component in normal physiology and disease with marked beneficial effects in the host defense mechanism. Exogenous administration of AM as well as its ectopic overexpression and the use of drugs, which potentiates its activity, are promising strategies for treatment of septic shock and several other pathogen-related disorders. Although major progress toward this end has been achieved over the past few years, our further understanding of the pleiotropic mechanisms involved with AM as a protective peptide is paramount to maximize its clinical application.
Tripterine inhibits the expression of adhesion molecules in activated endothelial cells
Authors: Zhang Deng-hai , Marconi Anthony , Xu Li-min , Yang Chun-xin , Sun Guo-wu , Feng Xiao-ling , Ling Chang-quan , Qin Wan-zhang , Uzan Georges , d’Alessio Patrizia
Published: June 2006

Cell adhesion molecules (CAM) expressed by vascular endothelium in response to cytokine stimulation play a key role in leukocyte adhesion to endothelium during the inflammatory response. Tripterine, a chemical compound of the Chinese plant Tripterygium wilfordii Hook f, displays anti-inflammatory properties in several animal models. However, mechanisms of its action are poorly understood. In the present study, we show that in inflammatory conditions, mimicked by tumor necrosis factor α (TNF-α) stimulation, pretreatment for 6 h with tripterine at nontoxic concentrations of 20–200 nM inhibits the expression of E-selectin, vascular cell adhesion molecule (CAM)-1 (VCAM-1), and intercellular adhesion molecule-1 (ICAM-1) in human umbilical vein endothelial cells (HUVEC) in a dose-dependent manner. Tripterine (200 nM) almost completely inhibits expression of VCAM-1 [50% inhibitory concentration (IC50)=52 nM] and ICAM-1 (IC50=51 nM) and 73% of E-selectin (IC50=94 nM). This inhibition effect is prominent, compared with that of dexamethasone, ibuprofen, methotrexate, or probucol, which revealed a much weaker inhibition at doses as high as 1 mM. Effects on endothelial CAM of other proinflammatory cytokines, such as interleukin-1β and interferon-γ, were also inhibited significantly by tripterine. Moreover, significant inhibition was equally observable in postincubation experiments. In addition, tripterine inhibited adhesion of human monocytes and T lymphocytes to TNF-α-stimulated HUVEC. Finally, tripterine inhibited TNF-α-driven CAM mRNA transcription and nuclear factor-κB nuclear (NF-κB) translocation. Hence, we describe a new mechanism of tripterine’s anti-inflammatory action obtained at nanomolar concentrations, owing to the negative regulation of cytokine-induced adhesion molecule expression and adhesiveness in human endothelium.
Release of surface-expressed lactoferrin from polymorphonuclear neutrophils after contact with CD4+T cells and its modulation on Th1/Th2 cytokine production
Authors: Li Ko-Jen , Lu Ming-Chi , Hsieh Song-Chou , Wu Cheng-Han , Yu Hsin-Su , Tsai Chang-Youh , Yu Chia-Li
Published: June 2006

It is conceivable that a membrane component(s) is transferred from antigen-presenting cells to T cells after antigenic stimulation. However, it is not clear whether a certain membrane component(s) is transferred from polymorphonuclear neturophils (PMN) to T cells for immunomodulation. In the presence study, we cocultured two of the three autologous cells—PMN, CD4+T, and red blood cells (RBC)—homotypically or heterotypically for 1 h. Spontaneous membrane exchange between autologous PMN-PMN and PMN-CD4+T but not between CD4+T-CD4+T or RBC-CD4+T was observed with a confocal microscope. Loss of membrane exchange between two paraformaldehyde-fixed cells suggests that mutual membrane exchange is via cell–cell contact. Different combinations of cellular enzyme-linked immunosorbent assay for measuring the binding between fixed cells and biotinylated cell lysates showed the same tendency. To identify the molecule(s) mediating PMN-CD4+T binding, we compared the banding of biotinylated PMN lysates and the banding of plain PMN lysate probed by biotinylated CD4+T lysate in 10% sodium dodecyl sulfate-polyacrylamide gel electrophoresis. We found that a 75- to 80-kDa surface-expressed molecule on PMN exists constantly to mediate PMN-CD4+T binding. Peptide analysis disclosed that the molecule had 99.8% identity with lactoferrin (LF). The expression of LF on system lupus erythematosis (SLE)-PMN is less than normal PMN. PMN-CD4+T coculture increased LF expression on CD4+T. Normal PMN and human milk-derived LF suppressed interferon-γ (IFN-γ) but enhanced interleukin (IL)-10 production of anti-CD3+anti-CD28-activated, normal CD4+T. In contrast, coculture of SLE-PMN and autologous CD4+T suppressed IFN-γ and IL-10 production. These results suggest that the surface-expressed LF released from PMN after contact with autologous CD4+T modulated its T helper cell type 1 (Th1)/Th2 cytokine production. Decreased LF expression on SLE-PMN abnormally modulates Th1/Th2 production by CD4+T cells.
IL-6 and IL-8 release is mediated via multiple signaling pathways after stimulating dendritic cells with lysophospholipids
Authors: Öz-Arslan Devrim , Rüscher Wolfgang , Myrtek Daniel , Ziemer Mirjana , Jin Yixin , Damaj Bassam B , Sorichter Stephan , Idzko Marco , Norgauer Johannes , Maghazachi Azzam A
Published: June 2006

Lysophosphatidic acid (LPA) and sphingosine 1-phosphate (S1P) are bioactive lipid mediators, which are known to play major roles in allergic reactions as well as in tumor pathogenesis. Here, the biological activities and signal pathways of these lysophospholipids (LPLs) in dendritic cells (DCs) were characterized further. Flow cytometric and immunoblot analyses indicate that immature as well as mature DCs express the LPL receptors S1P1, S1P3, S1P5, and LPA2, but not S1P2, S1P4, LPA1, or LPA3. Moreover, enzyme-linked immunosorbent assay experiments demonstrate that simultaneous addition of these LPLs to immature DCs in the presence of lipopolysaccharide enhanced the secretion of the inflammatory cytokines interleukin (IL)-6 and IL-8 in maturing DCs. In contrast, no modification of IL-6 or IL-8 release was observed after exposure of mature DCs to LPLs alone. In addition, studies with pertussis toxin and mitogen-activated protein kinase (MAPK) kinase inhibitor PD98059 suggested that Gi proteins and MAPK pathway are involved in these LPL-induced cell responses. Corroborating these findings, we observed that LPLs induce the phosphorylation of extracellular signal-regulated kinase 1/2 in immature DCs but not in mature DCs. Further analyses show that inhibitors of phosholipase D, Rho, and protein kinase C also inhibited the LPL-induced release of IL-6 and IL-8. Therefore, our findings suggest that lipopolysaccharide in DCs uncouples LPL receptors from the signal-transducing machinery during maturation and that exposure of LPLs at early time-points to maturing DCs modifies the proinflammatory capacity of mature DCs.
Chemotherapy in Advanced Gastric Cancer: A Systematic Review and Meta-Analysis Based on Aggregate Data
Authors: Wagner Anna D. , Grothe Wilfried , Haerting Johannes , Kleber Gerhard , Grothey Axel , Fleig Wolfgang E.
Published: June 2006

Purpose

This systematic review and meta-analysis were performed to assess the efficacy and tolerability of chemotherapy in patients with advanced gastric cancer.

Methods

Randomized phase II and III clinical trials on first-line chemotherapy in advanced gastric cancer were identified by electronic searches of Medline, Embase, the Cochrane Controlled Trials Register, and Cancerlit; hand searches of relevant abstract books and reference lists; and contact to experts. Meta-analysis was performed using the fixed-effect model. Overall survival, reported as hazard ratio (HR) with 95% CI, was the primary outcome measure.

Results

Analysis of chemotherapy versus best supportive care (HR = 0.39; 95% CI, 0.28 to 0.52) and combination versus single agent, mainly fluorouracil (FU) -based chemotherapy (HR = 0.83; 95% CI = 0.74 to 0.93) showed significant overall survival benefits in favor of chemotherapy and combination chemotherapy, respectively. In addition, comparisons of FU/cisplatin-containing regimens with versus without anthracyclines (HR = 0.77; 95% CI, 0.62 to 0.95) and FU/anthracycline-containing combinations with versus without cisplatin (HR = 0.83; 95% CI, 0.76 to 0.91) both demonstrated a significant survival benefit for the three-drug combination. Comparing irinotecan-containing versus nonirinotecan-containing combinations (mainly FU/cisplatin) resulted in a nonsignificant survival benefit in favor of the irinotecan-containing regimens (HR = 0.88; 95% CI, 0.73 to 1.06), but they have never been compared against a three-drug combination.

Conclusion

Best survival results are achieved with three-drug regimens containing FU, an anthracycline, and cisplatin. Among these, regimens including FU as bolus exhibit a higher rate of toxic deaths than regimens using a continuous infusion of FU, such as epirubicin, cisplatin, and continuous-infusion FU.
I Am a Trümmerfrau of Language
Authors: Jelinek Elfriede
Published: June 2006

Interviewed by Gitta Honegger
Princess Plays: Snow White
Authors: Jelinek Elfriede
Published: June 2006

Translated by Gitta Honegger
Princess Plays: Sleeping Beauty
Authors: Jelinek Elfriede
Published: June 2006

Translated by Gitta Honegger
Princess Plays: Jackie
Authors: Jelinek Elfriede
Published: June 2006

Translated by Gitta Honegger
Reflections on Forty Years of Théâtre du Soleil
Authors: Picon-Vallin Béatrice , Wehle Philippa , Solis René , Miller Judith , Wallon Emmanuel
Published: June 2006

Translated by Tom Sellar
Kinetics of Complexation between Cyclodextrin and Alcohol by Ultrasonic Relaxation Method: β-Cyclodextrin Solutions with 1-Butanol and 2-Methyl-2-propanol
Authors: Nishikawa Sadakatsu
Published: June 2006

The ultrasonic absorption coefficients over frequency range from 1.0 to 220 MHz were measured in aqueous β-cyclodextrin solutions with 1-butanol and 2-methyl-2-propanol at 25 °C. A clear single relaxational absorption with a relaxation frequency from 5 to 20 MHz was observed in a solution with 1-butanol, while the relaxational absorption was found in a lower frequency range in a solution with 2-methyl-2-propanol. The cause of the relaxation was attributed to a perturbation of a chemical equilibrium associated with complexation between β-cyclodextrin (host) and alcohol (guest). The rate and equilibrium constants for the complexation were determined from the concentration dependence of the relaxation frequency for the solution with 1-butanol. The standard volume change of the reaction was also obtained from the maximum absorption per wavelength. These results were compared with those for complexation between β-cyclodextrin and 1-propanol, and were considered in relation to the alcohol molecular structure. It was found that the rate of complex formation is almost independent of the guest molecule, and, therefore, the equilibrium constant for the complexation is controlled by the rate of departure of the guest molecule from the host. From this fact, the rate parameters for a solution with 2-methyl-2-propanol were estimated, and the calculated ultrasonic relaxation parameter was compared with the experimental data.
Membrane Phenomena in Nonisothermal Systems: Part 2. Effect of Hydrophobicity of Ion-Exchange Groups of Anion-Exchange Membranes on Thermoosmosis
Authors: Kiyono Ryotaro , Komoto Atsuhito , Tasaka Masayasu , Yamaguchi Takanori , Sata Toshikatsu
Published: June 2006

Solvent transport across poly(styrene)-based anion-exchange membranes with various ion-exchange groups was measured under a temperature gradient to discuss the effect of hydrophobicity of the membranes on thermoosmosis. Two varieties of poly(styrene)-based copolymer membranes with 10 and 14% divinylbenzene as cross-linking agent were prepared as base membranes. Benzyltrimethylammonium, benzyltriethylammonium, benzyltripropylammonium, benzyltributylammonium, and benzyltripentylammonium were introduced in the base membranes as anion-exchange groups. The thermoosmotic volume flux toward the hot solution side decreased with increasing the length of alkyl groups (increasing hydrophobicity of the groups), and at last, for the membranes with benzyltripentylammonium, the direction of thermoosmosis reversed: from the hot to the cold solution side as is observed for usual hydrophobic membranes. The transported energy and the mean transported entropy of water in the membranes estimated from the data of thermoosmosis and that of osmosis measurements increased with increasing the hydrophobicity of the ion-exchange groups introduced in the membranes.
Formation of Organic Compounds in Simulated Interstellar Media with High Energy Particles
Authors: Kasamatsu Takashi , Kaneko Takeo , Saito Takeshi , Kobayashi Kensei
Published: June 2006

Abiotic formation of amino acid precursors in interstellar dusts (ISDs) by cosmic radiation was quantitatively examined. In order to study the formation of organic compounds in ISDs, ice mixtures of carbon monoxide (or methane), ammonia, and water made in a cryostat at 10 K were irradiated with high energy protons. Irradiated ice products were warmed up to room temperature, while sublimed gases were analyzed with a quadrupole mass spectrometer. Some hydrocarbons and alcohols were detected. Amino acid precursors, which gave amino acids after acid-hydrolysis, were detected in non-volatile products remaining on the substrate at room temperature. G-values of glycine precursors from methanol, ammonia, and water in solid state irradiation were about 6 × 10−4, which was about two orders less than those in gasous state irradiation. The present results suggest that a considerable amount of organic compounds formed in extraterrestrial environments were supplied to the primitive earth before the origin of life.
Increased Redox-Reaction Rate of Quinhydrone at N-Substituted Polypyrrole Film Electrodes
Authors: Komura Teruhisa , Kobayashi Tomohiro , Yamaguti Takahiro , Takahasi Kousin
Published: June 2006

A poly[1-methyl-3-(pyrrol-1-ylmethyl)pyridinium] perchlorate-coated glassy carbon electrode noticeably decreased the charge-transfer resistance (Rt) of quinhydrone relative to a naked glassy carbon electrode. The redox species was not concentrated into a polymer film; this result differs markedly from the very good absorption of anthraquinonesulfonates and indigosulfonates by a polymer film. The dependence of Rt and the interfacial capacitance on the film thickness implies that the charge-transfer process occurs at the film-solution interface, because the polymer film is appreciably electronically conductive at positive potentials. Because of a change in the film conductivities with the potential, the polymer-coated electrode increased the anodic peak current of quinhydrone by three times, but decreased its cathodic peak current by two fifths, relative to that of a naked electrode. Although the decrease in Rt at a polymer-film electrode is somewhat ascribed to an increasing area, which is due to a porous film surface, the electrocatalytic effect of the polymer film can be attributed to an increasing standard rate constant of the charge-transfer process; this increase may be due to the adsorption of quinhydrone on the polymer surface.
Cooperative Redox Regulation of [4Fe-4S] Ferredoxin Model Arenethiolate Complexes by NH···S Hydrogen Bonds and an Aromatic C–H···S Interaction
Authors: Ueno Takafumi , Inohara Masahiro , Ueyama Norikazu , Nakamura Akira
Published: June 2006

A series of the model complexes containing ortho-substituted arenethiolato ligands, ((Et4N)2[Fe4S4(S-2-RCONHC6H4)4] {R = Ph (1), 4-MeO–C6H4 (2), and 4-F–C6H4 (3)} and (Et4N)2[Fe4S4{S-2,6-(RCONH)2C6H3}4] {R = Ph (4), 4-MeO–C6H4 (5), and 4-F–C6H4 (6)}) was synthesized and characterized by 1H NMR, IR spectroscopy, and cyclic voltammetry. The solution structures of these complexes are discussed based on their 1H NMR T1 data and molecular-dynamics calculations. Complex 4 has a shorter distance (av. 4.3 Å) between the protons of the benzoyl group and the inorganic sulfur atom of the [4Fe-4S] cluster than the corresponding ones of 1 (av. 6.2 Å). These results indicate the C–H···S interaction between the protons of the benzoyl group and the sulfur atom of the [4Fe-4S] cluster. The [Fe4S4(SAr)4]2−/[Fe4S4(SAr)4]3−redox potential for 1 and 4 are −0.86 and −0.65 V, respectively. The difference between 1 and 4 is Δ0.21 V. This is larger than the value Δ0.11 V between [Fe4S4(S-2-t-BuCONHC6H4)4]2− (−0.91 V) and [Fe4S4{S-2,6-(t-BuCONH)2C6H3}4]2− (−0.80 V), considered to be the difference between singly and doubly NH···S hydrogen-bonded complexes. The redox potentials for 1—6 follow the trend of the Hammett σm values, showing that the aromatic ring of the benzoyl group interacts with the [4Fe-4S] cluster directly. A cooperative effect between the C–H···S interaction and the NH···S hydrogen bond is thus found to regulate the redox potential of the model complexes.
Preparation and Stereochemistry of Cobalt(III) Complexes Containing 2,2′-Bipyridine 1,1′-Dioxide
Authors: Kanno Hideaki , Yano Takahiro , Sato Katsumi , Utsuno Shunji , Fujita Junnosuke
Published: June 2006

New cobalt(III) complexes, [Co(N4)(bpdo)]3+ (N4 = (en)2, (tn)2, (NH3)4, and tren; bpdo = 2,2′-bipyridine 1,1′-dioxide) and [Co(en)2(rac-3,3′-Me2bpdo)]3+ (rac-3,3′-Me2bpdo = racemic3,3′-dimethyl-2,2′-bipyridine 1,1′-dioxide), were obtained, where tn and tren denote trimethylenediamine and 2,2′,2″-triaminotriethylamine, respectively. The [Co(en or tn)2(bpdo)]3+ and [Co(en)2(rac-3,3′-Me2bpdo)]3+ complexes form only one of two possible racemic pairs of diastereomers, which were resolved by SP-Sephadex column chromatography. Each pair of these complexes was assigned to have a lel(Δ(λ), Λ(δ)) structure on the basis of the 13C NMR and circular dichroism spectra, and the absolute configuration of optically active free 3,3′-Me2bpdo ligand recovered from the resolved complex. The tetraammine and tren complexes were resolved into a pair of enantiomers by a chemical method, but rapidly racemized in water with the rate of 7.33 × 10−3 s−1 and 1.16 × 10−3 s−1, respectively, at 10.0 °C. An intramolecular conformational inversion of the skew bpdo chelate ring (δ    λ) was proposed for the racemization.
Formation and Conversion of Yellow Molybdophosphonate Complexes in Aqueous-Organic Media
Authors: Ueda Tadaharu , Sano Ken-ichi , Himeno Sadayuki , Hori Toshitaka
Published: June 2006

The reaction of Mo(VI) with PHO32− in acidic solution containing CH3COCH3 or CH3CN led to the formation of the previously unknown 15-molybdobis(phosphonate) complex. The addition of an excess of PHO32− caused 15-molybdobis(phosphonate) to transform into 16-molybdotetrakis(phosphonate) in the CH3COCH3–water system. In the CH3CN–water system, on the other hand, the spontaneous transformation of 15-molybdobis(phosphonate) into 12-molybdobis(phosphonate) occurred in the presence of an excess of PHO32− or at greater acidities; the latter complex was also formed in aqueous media. The yellow heteropolyanions underwent electrochemical reductions, yielding mixed-valence blue species.
Evidence for Spiro-Conjugation in Perpendicularly-Linked Pentamethinestreptocyanine Dimers
Authors: Katoh Takashi , Ogawa Keizo , Inagaki Yoshio , Okazaki Renji
Published: June 2006

Perpendicularly-linked pentamethinestreptocyanine dimers (1) in which the two cyanine moieties are linked at the center carbon atoms of the methine chains were prepared. The absorption spectra of 1 in solution showed two peaks at 446 and 406 nm, which are attributed to the splitting of the HOMO levels through spiro-conjugation between the two cyanine moieties, as calculated from the INDO/S-CI method. The reduction potential of 1 positively shifted with respect to that of the corresponding monomer (2). The oxidation polarogram of 1 showed two waves, with the first potential negatively shifting compared to that of 2.
Synthesis and Properties of Dimethyl- and Monomethylbis(phosphite)palladium(II) Complexes
Authors: Kayaki Yoshihito , Shimizu Isao , Yamamoto Akio
Published: June 2006

New dimethylpalladium complexes having alkyl and aryl phosphites as the supporting ligands, cis-[PdMe2{P(OR)3}2] (R = Me, 1a; Ph, 1b), have been prepared by two routes, (1) by the reaction of [Pd(acac)2] with [AlMe2(OEt)] in the presence of the phosphite ligands, and (2) by the ligand exchange reaction of [PdMe2(cod)] (COD = 1,5-cyclooctadiene) with two molar amounts of the phosphites. Monomethylpalladium chloride complexes, [PdMe(Cl){P(OR)3}2] (R = Me, 2a; Ph, 2b; Pri, 2c) have been prepared by ligand exchange reaction of [PdMe(Cl)(cod)] with two molar amounts of the phosphites, whereas [PdMe(OAc){P(OR)3}2] (R = Me, 3a; Ph, 3b) has been synthesized by treatment of 1 with acetic acid. Strong influence of the coordinated phosphite ligand on the cis or trans configuration of the monomethylpalladium complexes was observed, the results being in contrast with those of complexes having the trimethylphosphine ligands that give preferentially trans complexes. Removal of the chloride ligand in 2 with an equimolar amount of AgBF4 or treatment of the dimethylpalladium complex 1 with HBF4 in the expectation of obtaining a bis(phosphite)-coordinated complex led to formation of a mixture of the tris(phosphite) complex, [PdMe{P(OR)3}3]+BF4− and the mono-phosphite complex [PdMe{P(OR)3}(s)2]+BF4− (s = solvent), presumably through the rapid disproportionation of an unstable intermediate [PdMe{P(OR)3}2(s)]+BF4−.
Reduction of Methemoglobin via Electron Transfer across the Bilayer Membrane of Hb Vesicles
Authors: Takeoka Shinji , Ohgushi Takeru , Nishide Hiroyuki , Tsuchida Eishun
Published: June 2006

The hemoglobin vesicle (HbV) has a cellular structure which encapsulates concentrated Hb in the inner aqueous phase of a phospholipid bilayer vesicle. Hb is gradually autoxidized to methemoglobin (metHb), which can not bind oxygen during oxygen transport under physiological conditions. In order to reduce metHb in HbV, we evaluated the reduction of metHb by electron transfer across the bilayer membrane of HbV from a reductant added to the outer aqueous phase. Water-soluble methylene blue (MB) and hydrophobic ubiquinone 10 (UQ) were selected as electron mediators. Under a nitrogen atmosphere, the addition of the reduced form nicotinamide-adenine dinucleotide (NADH) to the outer aqueous phase of UQ-incorporated HbV showed only a slow reduction rate for metHb. On the other hand, when MB and NADH were added under a nitrogen atmosphere to HbV containing 40% metHb, a rapid decrease in the metHb percentage was observed. The entire reaction was controlled by a reaction with NADH and MB in the outer aqueous phase. Under aerobic conditions, the decrease in the efficiency of the metHb reduction and rapid oxidation after reaching the minimal metHb percentage were observed. This was confirmed to be due to the influence of hydrogen peroxide; the decrease was prevented by the co-encapsulation of catalase.
Mechanism of a Chain-Extending Reaction in the Synthesis of Segmented Poly(urethane–urea) Using Blocked Ethylenediamine
Authors: Nakano Yasuhiro , Yamazaki Emiko , Hanahata Hiroyuki , Okajima Kunihiko , Kitahama Yoshiharu
Published: June 2006

An attempt was made to clarify the mechanism of a chain-extending reaction of NCO-terminated prepolymers in the synthesis of segmented poly(urethane–urea) using blocked ethylenediamine (EDA) with acetone (ACE). For this purpose, an ACE/EDA mixture was allowed to react with phenyl isocyanate (PhNCO) as a model of the prepolymer. The reaction of PhNCO with the ACE/EDA mixture, which was proved to contain ketimine and imidazolidine compounds by NMR measurements, gave 1,1′-ethylenebis[3-phenylurea] (M-Ur-1) as the main product; at the same time 1,3-diphenylurea (1,3-DPU) was assumed to be formed as a side-reaction product between PhNCO and H2O, inevitably existing in the mixture as the result of condensation. From a considerable increase in the yield of M-Ur-1 upon the addition of an excess amount of H2O to the reaction system, H2O was elucidated to participate in the acceleration of the main reaction, giving M-Ur-1 as well as in the side reaction, yielding 1,3-DPU. The excess H2O added to the system might preferentially facilitate the former reaction, rather than the latter.
Gels of Bis[1,2-bis(3,4-di-n-alkoxyphenyl)ethanedione dioximato]palladium(II) Complexes
Authors: Ohta Kazuchika , Moriya Mitsuo , Ikejima Mayumi , Hasebe Hiroshi , Kobayashi Nagao , Yamamoto Iwao
Published: June 2006

Bis[1,2-bis(3,4-di-n-alkoxyphenyl)ethanedione dioximato]palladium(II) complexes (abbreviated as [Pd{(CnO)4dpg}2]; n = 7—12) form gels in an over-concentrated n-hexane solution. We have developed a specific cell for X-ray diffraction in order to determine the gel structure. The gel has a two-dimensional hexagonal structure which is similar to the inverted hexagonal phase of lyotropic liquid crystals. The electronic spectra were measured for the gel and for a chloroform solution, which dose not form a gel. As a result, it has become apparent that a 4dz2–5pz intermolecular charge-transfer transition between the neighboring palladium ions is the main driving force of the gel formation. The circular dichroism and magnetic circular dichroism of the gel suggested that this complex has a stack of left-handed helicity. The complex also has a thermotropic liquid-crystalline state, as previously reported. Hence, these three kinds of states are closely related to each other in terms of the formation of molecular aggregates.
A Novel Crosslinking–Decrosslinking System of Polymers Having Spiro Orthoester Moieties in the Side Chains
Authors: Endo Takeshi , Suzuki Takashi , Sanda Fumio , Takata Toshikazu
Published: June 2006

Acid-catalyzed reversible crosslinking–decrosslinking of polymers having spiro orthoester groups in the side chains was carried out. The copolymers obtained by the radical copolymerizations of 2-methylene-1,4,6-trioxaspiro[4.6]undecane with acrylonitrile, methyl, cyclohexyl, and 2-ethylhexyl acrylates were treated with trifluoroacetic acid (5 mol%) at −10 °C for 1 h in CH2Cl2 (4.2 M) to afford the crosslinked polymers in 69—99% yields. The crosslinked polymers were then treated with trifluoroacetic acid at a low concentration (0.1 M) in CH2Cl2 at room temperature for 1 h to give the original polymers in 55—99% yields. These results strongly support the conclusion that the acid-catalyzed reversible crosslinking–decrosslinking of the polymers possessing the spiro orthoester groups in the side chains could be constructed.
Ultrafast Spectroscopy with Broad Probe Spectral Range Extending from Near Ultraviolet to Near Infrared
Authors: Kobayashi Takayoshi
Published: June 2006

A broad-band femtosecond spectroscopy apparatus has been developed. The spectrum of the probe light pulse extends from 400 nm to 3.0 μm, covering near ultraviolet (NUV), visible (VIS), and near infrared (NIR) ranges. The time resolution is better than 100 fs in the NUV and VIS regions, and better than 200 fs in the NIR region. The minimum detectable absorbance change is 2 × 10−3 for wavelengths between 400 nm and 1.6 μm and 3 × 10−3 between 1.6 μm and 3.0 μm. A tunable light pulse for the pump was also developed using the second-harmonic generation (SHG) and sum-frequency generation (SFG) in the cavity of the optical parametric oscillator. The tuning ranges of SHG and SFG are 529—585 nm and 426—483 nm, respectively. The study of ultrafast geometrical relaxation processes in a substituted poly(phenylacetylene) by the use of the broad spectroscopy apparatus is described as an example at the end.
Synthesis of S2−- and PF2O2-Bridged Dinuclear Ruthenium(IV) Complex Obtained from the Reaction of Disulfide-Bridged Ruthenium(III) Dimer Complex with Dioxygen and Water
Authors: Matsumoto Kazuko , Sano Yoichi , Kawano Masaki , Uemura Hiroyuki , Matsunami Jun , Sato Toshio
Published: June 2006

Reaction of [{Ru(CH3CN)3[P(OMe)3]2}2(μ-S2)](PF6)3 with a mixture of acetylene and O2 gave a novel ruthenium(IV) dimer complex [{Ru(IV)(PFO3)[P(OMe)3]2}2(μ-S)(μ-PF2O2)2]. The newly formed bridging and terminal ligands PF2O2− and PFO32− are produced from the reaction of PF6− with trace amounts of H2O in the solvent. Although acetylene is not incorporated in the final product, it is necessary to accelerate the reaction. Ruthenium(IV) complexes with S2− ligand are rare and only two examples are previously known. The crystal of [{Ru(PFO3)[P(OMe)3]2}2(μ-S)(μ-PF2O2)2] is monoclinic, space group P21/n, a = 11.061(5), b = 20.764(4), c = 17.074(3) Å, β = 95.74(2)°, V = 3901(1) Å3, and Z = 4. The bridging PF2O2− ligand coordinates to Ru atoms with the two oxygen atoms, while the terminal PFO32− ligand coordinates to a Ru atom with one of the oxygen atoms. The molecular structure is confirmed by 31P and 19F NMR spectroscopy.
Discrimination of Doxylpalmitic Acids by γ-Cyclodextrin: ESR Study of Stability, Conformation, and Dynamics
Authors: Tanaka Hisao , Kato Naoko , Kawazura Hiroshi
Published: June 2006

Six palmitic acids labeled at different methylene positions by paramagnetic doxyl moiety were used as guests in order to examine molecular discrimination using γ-cyclodextrin (γ-CD). The DPA inclusion complexes using γ-CD in an aqueous solution were characterized according to stability, conformation, and dynamics at 25 °C, mainly based on ESR spectral analyses and supported by force-field calculations. The stability was equal among all DPA complexes, as represented by the formation constant Ks = 8.0(±0.5) × 102 M−1 (M = mol dm−3), corresponding to the conformation constant when the palmitate chain penetrates a CD cavity and the doxyl ring locates inside the cavity. Both overall molecular motion and chain segmental motion of DPA, represented by the parallel (Rzz) and perpendicular components (Rxx = Ryy) of the rotational diffusion tensor, respectively, were significantly restricted in inclusion state. The magnitude of restriction of segmental motion increased towards the chain terminals from the center, indicating that faster segmental motion was restricted at a higher rate. Thus, a series of DPAs were discriminated by γ-CD in terms of chain segmental motion but not in terms of stability, to present a typical example of dynamic molecular discrimination.
Semiempirical (AM1) Studies of Possible and Preferred Site(s) of Porotnation in the Gas Phase for Polyfunctional Nitrogen Bases: N1,N1-Dimethyl-N2-azinylformamidines
Authors: Raczynska Ewa D , Taft Robert W
Published: June 2006

Proton affinities for seven polyfunctional nitrogen bases (N1,N1-dimethyl-N2-azinylformamidines) containing one amidine moiety and one, two or three nitrogen atoms in ortho-, meta-, and/or para-positions of the heterocyclic six-membered group have been predicted by semiempirical AM1 method. The preferred site(s) of protonation and exceptionally high gas-phase basicity of N1,N1-dimethyl-N2-azinylformamidines containing 2-azinyl group antiperiplanar to the functional carbon atom in the amidine moiety have been discussed. The effects of one group on the basicity of the other one have been compared with those found for the corresponding model amidines and azines.
Superdelocalizabilities of Linear Chains
Authors: Isihara Makoto
Published: June 2006

This paper analyzes superdelocalizabilities (SDs) of even-membered linear chains in a simple noncomputational way. Two basic relationships connecting SDs to bond orders are prepared in general form and applied to linear chains to provide a plain analytic expression to SDs. Behaviors of SDs in long linear chains are examined by using this analytic expression. Simple estimation formulas are derived for SDs near the end and in the middle of a long linear chain and the distinctive reactivity of end sites is fully verified. Comparisons with behaviors of frontier electron densities and frontier SDs manifest that these approximate indices cannot substitute for SDs in long linear chains.
Synthesis and Optical Properties of Transparent LiAl5O8 : Co2+ Films by the Sol–Gel Method
Authors: Ishihara Tsuguo , Tanaka Katsuhisa , Hirao Kazuyuki , Soga Naohiro
Published: June 2006

A transparent LiAl5O8 : Co2+ film was prepared by the sol–gel method using LiNO3, Al(i-OC3H7)3, and Co(NO3)2·6H2O. The microstructure and optical properties of the film were examined using X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), optical absorption, and fluorescence measurements. The XRD analysis indicated that a (110)-oriented LiAl5O8 film is formed when the gel film is heat-treated at 773 K. The XRD patterns of LiAl5O8 films heat-treated above 1173 K manifest diffraction lines assigned to reflections from the (110), (220), and (440) planes. In contrast, only the diffraction lines corresponding to the (220) and (440) planes were observed in a LiAl5O8 film heat-treated below 1073 K. These results suggest that LiAl5O8 films heat-treated below 1073 K and above 1173 K possess disordered and ordered structures, respectively. The LiAl5O8 : Co2+ films obtained by a heat treatment below 1173 K, which contain crystallites of less than 10 nm, are optically transparent. The optical absorption spectra at room temperature indicate that the absorption band due to the 4A2 → 4T1(P) transition of Co2+ ions in tetrahedral sites showed three peaks (540, 580, and 625 nm). The fluorescence spectra of the films obtained by a heat treatment above 1173 K manifest a sharp line at around 658 nm with vibronic sidebands in the long-wavelength region. The emission bands are ascribed to transition from 4T1(P) to 4A2 of Co2+ ions in tetrahedral sites in the ordered phase.
Determination of Lead(II) by Electrothermal Atomization Atomic Absorption Spectrometry after Coprecipitation with Gallium(III) Phosphate
Authors: Kagaya Shigehiro , Ueda Joichi
Published: June 2006

Gallium(III) phosphate coprecipitates quantitatively 0.1—2.0 μg of lead(II) from 100—500 cm3 of a sample solution at pH 2.5—6.0. The coprecipitated lead(II) can be sensitively determined by electrothermal atomization atomic absorption spectrometry without any influence of gallium(III) phosphate. The calibration curve is linear from 4 to 80 ng cm−3 for lead(II). The detection limit (signal/noise = 2) is 0.095 ng cm−3 of lead(II) in 500 cm3 of the initial sample solution. Thirty-four diverse ions tested did not interfere seriously with the determination of lead(II). This method was successfully applied to the determination of lead(II) in tap and river water.
Formation of 3-Methylene-1,4-cyclohexadienes from α,α,α′,α′-Tetraaryl-1,4-benzenedimethanols by the Intramolecular Migration of an Aryl Group
Authors: Wada Masanori , Wei Wen-hao , Kirishima Katsuhiko , Natsume Satoko , Erabi Tatsuo
Published: June 2006

By reactions of diethyl p-phthalate with 2,6-dimethoxyphenyllithium, ΦLi, a tri-substituted compound, p-HOCΦ2C6H4C(O)Φ (1), or tetra-substituted 1,4-benzenedimethanol, p-HOCΦ2C6H4CΦ2OH (2a), were obtained. Compound 1 further reacted with aryllithium, ArLi, to give the 1,4-benzenedimethanols, p-HOCΦ2C6H4CArΦOH (Ar = 4-MeC6H42b, 4-MeOC6H42c). When 2a was treated with acid in dimethyl sulfoxide, 3-(2,6-dimethoxybenzoyl)-3-(2,6-dimethoxyphenyl)-6-[bis(2,6-dimethoxyphenyl)methylene]-1,4-cyclohexadiene, (4a) was obtained in quantitative yield under a variety of conditions. The reaction is understood to involve an initial formation of carbenium ion, [p-Φ2C+–C6H4CΦ2OH] (3a), of which the positive charge must be partly shared with the other end of the p-phenylene ring, where one of the neighboring Φ-groups migrates. Reactions in acetone resulted to give 4a or dark-violet crystals of (2′,6′-dimethoxy-4-biphenylyl)bis(2,6-dimethoxyphenyl)carbenium perchlorate, [(4-ΦC6H4)CΦ2]ClO4, depending on the reaction conditions. Reactions in methanol, ethanol, or in hot 2-propanol resulted to give the reduced compound, (4-ΦC6H4)Φ2CH. The 1,4-benzenedimethanols, 2b and 2c, also reacted with perchloric acid in dimethyl sulfoxide to form the 3-methylene-1,4-cyclohexadiene derivatives, (Ar = 4-MeC6H44b, 4-MeOC6H44c), respectively. Evidence is given by the 1H NMR spectrum, which shows the formation of intermediate carbenium ions 3a—c.
Scandium(III) Perfluorooctanesulfonate [Sc(OPf)3] : A Novel Catalyst for the Hetero Diels–Alder Reaction of Aldehydes with Non-Activated Dienes
Authors: Hanamoto Takeshi , Sugimoto Yuichi , Jin Yong Zhi , Inanaga Junji
Published: June 2006

Scandium(III) perfluorooctanesulfonate [scandium(III) perflate, Sc(OPf)3] was prepared from either scandium(III) chloride or oxide and perfluorooctanesulfonic acid. The perflate thus obtained acts as a novel Lewis acid catalyst for the intermolecular hetero Diels–Alder reaction of aldehydes with non-activated dienes under mild conditions. The characteristic features of the catalyst include (i) low hygroscopicity, (ii) ease of handling, and (iii) robustness for the recycling use.
Dehydrooligopeptides. XX. Unusual Peptide Bond Cleavage of Dehydrotripeptide Esters Containing α-Dehydroamino Acid Residue at P2 by Using Papain
Authors: Shin Chung-gi , Arai Kazushige , Hotta Keitaro , Kakusho Takeshi
Published: June 2006

Enzymatic ester hydrolysis and coupling of various N-protected Δ2-dehydrotripeptide methyl esters (Boc–AA–ΔAA–AA–OMe) (4) by using protease papain in McIlvaine buffer are mainly described. The substrates (4) used were prepared by one-pot coupling of N-carboxy-α-dehydroamino acid anhydride (ΔAA·NCA) with N- and C-component l-α-amino acids (AA). Even in the enzymatic reaction of 4 containing an unusual ΔAA residue, the normal ester hydrolysis took place to give Boc–AA–ΔAA–AA–OH (6) and, in certain cases, the interesting unusual peptide bond cleavage at P2 of 6 occured further to give the unexpected N-(1,2-dioxoalkyl)–AA–OH. Besides examining in detail the differences between the enzymatic actions to the structures of 4, we also studied the mechanisms of the ester and peptide bond hydrolyses. As the results, the reverse enzymatic coupling of 4 with H–AA–ΔVal–OMe was first achieved to give dehydropentapeptide containing two ΔAA residues.
Enzymatic Preparation of (S)-3-Hydroxytetradecanoic Acid and Synthesis of Unnatural Analogues of Lipid A Containing the (S)-Acid
Authors: Liu Wen-Chi , Oikawa Masato , Fukase Koichi , Suda Yasuo , Winarno Hendig , Mori Saeko , Hashimoto Masahito , Kusumoto Shoichi
Published: June 2006

Synthesis of unnatural analogues, that contain (S)-3-hydroxytetradecanoyl moieties in place of the corresponding natural (R)-isomers, of both lipid A and its biosynthetic precursor, designated precursor Ia or lipid IVA, has been achieved through our recently developed procedure. (S)-3-Hydroxytetradecanoic acid was prepared from its racemate through the optical resolution by the use of a lipase and subsequent fractional recrystallization. The (S)-acyl analogue of lipid A exhibited slightly stronger interleukin-6 inducing activity than the corresponding natural lipid A, and the (S)-acyl analogue of the biosynthetic precursor was far more active than the natural precursor in inhibiting the induction of interleukin-6 by lipopolysaccharide.
Effects of High-Pressure on the Activity and Spectroscopic Properties of Carboxypeptidase Y
Authors: Kunugi Shigeru , Yanagi Yuuichi , Kitayaki Moto , Tanaka Naoki , Uehara-Kunugi Yukiko
Published: June 2006

The effects of high pressure, up to 400 MPa, on the catalytic activity and the fluorescence and CD of carboxypeptidase Y (CPDY) were investigated.

CPDY showed a pH-dependent Suc–Ala–Ala–Pro–Phe–pNA hydrolysis similar to other neutral substrates. The apparent second-order rate showed a gradual decrease with increasing pressure, which was related to an increase in Km and a decrease in kcat.

The intrinsic fluorescence of CPDY showed a gradual decrease in the intensity and a red shift in the maximum wavelength with pressure. The transition curve did not follow a simple tow-state transition, but contained at least three states. The first transition occurred at around 100 MPa and the second one occurred at pressures higher than 200 MPa. After incubation at 300 MPa, both the peak intensity and the maximum wavelength did not show complete restoration; the pressure-induced change is substantially irreversible.

The latter change corresponds to the increased binding of a fluorescent hydrophobic probe molecule (8-anilino-1-naphthalenesulfonic acid) to this protein; however, the CD spectrum showed practically no evidence of irreversible changes in the protein’s secondary structure.
Bioactive Compounds from the Sea Hares of Two Genera: Aplysia and Dolabella
Authors: Yamada Kiyoyuki , Kigoshi Hideo
Published: June 2006

This account describes the chemistry of the bioactive compounds isolated from the sea hares belonging to two genera: Aplysia and Dolabella. The bioactive compounds are classified as i) polyketides, ii) terpenes, iii) peptides and depsipeptides, and iv) others. Special emphasis is placed on the chemistry of cytotoxic compounds such as aplyronines and dolastatins that were obtained in our laboratory: Their isolation, structural elucidation, synthesis, and selected bioactivities data are summarized.
Oscillations of Membrane Current or Membrane Potential and Voltammetric Elucidation of Their Mechanisms
Authors: Maeda Kohji , Hyogo Wataru , Nagami Shuzo , Kihara Sorin
Published: June 2006

Novel oscillations of membrane current or membrane potential were observed when the transfer of Na+ from one aqueous solution (W1) containing 0.1 M NaCl to another (W2) in the absence of Na+ through a liquid membrane (LM) containing dilute Na+ was forced by an applied membrane potential or membrane current, respectively. The current oscillation was induced by the addition of acetylcholine in W1, and inhibited by the addition of such hydrophobic ions as tetraalkylammonium ions or glutamate ion in W1. These oscillations were similar to those at biomembranes with so-called “sodium channels” as regards both induction and inhibition, though the liquid membrane system did not contain any channel proteins. The current and potential oscillations were also inhibited by the addition of bovine serum albumin in W2. The mechanisms of the oscillations, the induction and the inhibitions were elucidated by referring to voltammograms for the ion transfer through a membrane as well as those at aqueous/membrane interfaces, and by taking into account the adsorption of Na+ at the LM/W2 interface. Various LM systems which exhibit the oscillations accompanied by transports of ions other than Na+ were also investigated, and the general feature of the oscillations of membrane current or potential is discussed.
Three-Dimensional Structural Feature Search of Proteins
Authors: Kato Hiroaki , Takahashi Yoshimasa
Published: June 2006

This paper describes a three-dimensional (3D) structural feature search, or motif search, of proteins using SS3D-P. Our present approach is based upon the use of a substructure searching program for small organic molecules, SS3D, reported in our previous work. In SS3D-P, the 3D structure of a protein is approximated with the coordinates of α-carbon atoms of the main chain, and treated as a molecular graph that is represented using a distance matrix. The program allows us to specify the tolerance value of the inter-residual distances to be compared. Several characterization schemes are also available for the different amino acid residues that can be distinguished. The program we have developed was validated by search trials with 3D query patterns of known protein motif structures: the P-loop, the EF-hand, and the Zinc finger motif using Protein Data Bank (PDB) structure files.
The Surface Heterogeneity of Supported Platinum Catalysts as Studied by the Interrupted Temperature-Programmed Desorption of Carbon Monoxide
Authors: Arai Masahiko , Fukushima Makane , Nishiyama Yoshiyuki
Published: June 2006

The interrupted temperature-programmed desorption of carbon monoxide was used to characterize the surface heterogeneity of supported platinum catalysts. The surface of platinum particles is divided into two different groups of desorption sites. For one group, the surface diffusion of carbon monoxide takes place easily, and it desorbs at low temperatures. For the other, the desorption of carbon monoxide requires higher temperatures, and surface diffusion does not occur. For the latter group, the distribution of the activation energy of desorption is determined by a method that the authors have recently developed (Appl. Surf. Sci., 89, 11 (1995)).