bluuebunny/crossref_metadata_2025 huggingface dataset:
Aryl Hydrocarbon Receptor Activation Impairs Cortisol Response to Stress in Rainbow Trout by Disrupting the Rate-Limiting Steps in Steroidogenesis
Authors: Aluru Neelakanteswar , Vijayan Mathilakath M.
Published: January 2006

Anthropogenic stressors activating aryl hydrocarbon (Ah) receptor signaling, including polychlorinated biphenyls, impair the adaptive corticosteroid response to stress, but the mechanisms involved are far from clear. Using Ah receptor agonist (β-naphthoflavone; BNF) and antagonist (resveratrol; RVT), we tested the hypothesis that steroidogenic pathway is a target for endocrine disruption by xenobiotics activating Ah receptor signaling. Trout (Oncorhynchus mykiss) were fed BNF (10 mg/kg·d), RVT (20 mg/kg·d) or a combination of both for 5 d, and subjected to a handling disturbance. BNF induced cytochrome P4501A1 expression in the interrenal tissue and liver, whereas this response was abolished by RVT, confirming Ah receptor activation. In control fish, handling disturbance transiently elevated plasma cortisol and glucose levels and transcript levels of interrenal steroidogenic acute regulatory protein (StAR), cytochrome P450 cholesterol side chain cleavage (P450scc) and 11β-hydroxylase over a 24-h period. BNF treatment attenuated this stressor-induced plasma and interrenal responses; these BNF-mediated responses were reverted back to the control levels in the presence of RVT. We further examined whether these in vivo impacts of BNF on steroidogenesis can be mimicked in vitro using interrenal tissue preparations. BNF depressed ACTH-mediated cortisol production, and this decrease corresponded with lower StAR and P450scc, but not 11β-hydroxylase mRNA abundance. RVT eliminated this BNF-mediated depression of interrenal corticosteroidogenesis in vitro. Altogether, xenobiotics activating Ah receptor signaling are steroidogenic disruptors, and the mode of action includes inhibition of StAR and P450scc, the rate-limiting steps in steroidogenesis.
Haplotype Insufficiency for Suppressor of Cytokine Signaling-2 Enhances Intestinal Growth and Promotes Polyp Formation in Growth Hormone-Transgenic Mice
Authors: Michaylira Carmen Z. , Ramocki Nicole M. , Simmons James G. , Tanner C. Kirby , McNaughton Kirk K. , Woosley John T. , Greenhalgh Christopher J. , Lund P. Kay
Published: January 2006

GH may improve intestinal growth or function in patients with short bowel syndrome. Excessive trophic effects of GH or IGF-I may contribute to neoplastic growth or increased colorectal cancer risk in acromegaly. Identification of mechanisms that limit the tumorigenic potential of GH and IGF-I is desirable. Suppressor of cytokine signaling-2 (SOCS2) limits GH action on body and organ growth, but its role in GH action on intestine is unknown. We tested the hypothesis that SOCS2 limits GH-induced intestinal growth or neoplasia in vivo. GH-transgenic (GH-TG) mice were crossed with SOCS2 null mice to generate wild-type (WT) or transgenic (TG) mice with zero (HO-WT; HO-TG), one (HT-WT; HT-TG), or two (WT-WT; WT-TG) functional SOCS2 genes. No HO-TG mice were derived from crossbreeding. WT-WT, HT-WT, WT-TG, and HT-TG were compared. Body weight, small intestine and colon growth, and levels of jejunal IGF-I and sucrase-isomaltase mRNAs were assessed. Colon was analyzed for abnormal lesions. HT-WT did not differ from WT-WT. Compared with WT-TG, HT-TG had significantly increased body weight, small intestine growth, and local IGF-I expression and decreased sucrase-isomaltase expression. HT-TG colon spontaneously developed multiple hyperplastic and lymphoid polyps. GH-induced activation of STAT5 DNA binding activity was enhanced in intestine of SOCS2 null mice compared with WT control. Haplotype insufficiency for SOCS2 promotes trophic actions of GH in small intestine and promotes preneoplastic growth in colon during excess GH. Small variations in SOCS2 expression levels may significantly influence the outcome of therapeutic GH or acromegaly in intestine.
Effects of Hepatic Expression of the High-Density Lipoprotein Receptor SR-BI on Lipoprotein Metabolism and Female Fertility
Authors: Yesilaltay Ayce , Morales María Gabriela , Amigo Ludwig , Zanlungo Silvana , Rigotti Attilio , Karackattu Sharon L. , Donahee Mary H. , Kozarsky Karen F. , Krieger Monty
Published: January 2006

The etiology of human female infertility is often uncertain. The sterility of high-density lipoprotein (HDL) receptor-negative (SR-BI−/−) female mice suggests a link between female infertility and abnormal lipoprotein metabolism. SR-BI−/− mice exhibit elevated plasma total cholesterol [with normal-sized and abnormally large HDL and high unesterified to total plasma cholesterol (UC:TC) ratio]. We explored the influence of hepatic SR-BI on female fertility by inducing hepatic SR-BI expression in SR-BI−/− animals by adenovirus transduction or stable transgenesis. For transgenes, we used both wild-type SR-BI and a double-point mutant, Q402R/Q418R (SR-BI-RR), which is unable to bind to and mediate lipid transfer from wild-type HDL normally, but retains virtually normal lipid transport activities with low-density lipoprotein. Essentially wild-type levels of hepatic SR-BI expression in SR-BI−/− mice restored to nearly normal the HDL size distribution and plasma UC:TC ratio, whereas approximately 7- to 40-fold overexpression dramatically lowered plasma TC and increased biliary cholesterol secretion. In contrast, SR-BI-RR overexpression had little effect on SR-BI+/+ mice, but in SR-BI−/− mice, it substantially reduced levels of abnormally large HDL and normalized the UC:TC ratio. In all cases, hepatic transgenic expression restored female fertility. Overexpression in SR-BI−/− mice of lecithin:cholesterol acyl transferase, which esterifies plasma HDL cholesterol, did not normalize the UC:TC ratio, probably because the abnormal HDL was a poor substrate, and did not restore fertility. Thus, hepatic SR-BI-mediated lipoprotein metabolism influences murine female fertility, raising the possibility that dyslipidemia might contribute to human female infertility and that targeting lipoprotein metabolism might complement current assisted reproductive technologies.
Immunoglobulin G from Patients with Graves’ Disease Induces Interleukin-16 and RANTES Expression in Cultured Human Thyrocytes: A Putative Mechanism for T-Cell Infiltration of the Thyroid in Autoimmune Disease
Authors: Gianoukakis Andrew G. , Douglas Raymond S. , King Chris S. , Cruikshank William W. , Smith Terry J.
Published: January 2006

Mechanisms underlying lymphocyte infiltration of the thyroid gland and orbit in Graves’ disease (GD) are poorly understood. The IGF-I receptor (IGF-IR) is a newly recognized self-antigen that, when activated in GD fibroblasts by IGF-I or GD-IgGs, provokes the expression of IL-16 and RANTES (regulated upon activation, normal T cell expressed and secreted)-dependent T lymphocyte chemoattraction and hyaluronan synthesis. IL-16 is a CD4+-specific ligand, and RANTES is a C-C chemokine. Here we report that IGF-I and GD-IgG could induce IL-16 and RANTES in cultured human thyrocytes in a time-dependent manner. Importantly, human TSH failed to induce either chemoattractant. This induction could be attenuated by dexamethasone. Rapamycin, a specific inhibitor of the FRAP/mammalian target of rapamycin/p70s6k pathway, prevented GD-IgG-provoked IL-16 synthesis. IH7, a monoclonal antibody directed at IGF-IR also blocked the induction of chemoattraction as well as RANTES mRNA synthesis. Our findings suggest that thyrocytes can be activated by GD-IgG and IGF-I to express powerful T-cell chemoattractants. These actions of GD-IgG appear to be mediated through pathways independent of the TSH receptor. Thus, in GD, thyrocytes may participate directly in lymphocyte recruitment through their expression of IL-16 and RANTES.
Stress History and Pubertal Development Interact to Shape Hypothalamic-Pituitary-Adrenal Axis Plasticity
Authors: Romeo Russell D. , Bellani Rudy , Karatsoreos Ilia N. , Chhua Nara , Vernov Mary , Conrad Cheryl D. , McEwen Bruce S.
Published: January 2006

Both the magnitude and the duration of the hormonal stress response change dramatically during neonatal development and aging as well as with prior experience with a stressor. However, surprisingly little is known with regard to how pubertal maturation and experience with stress interact to affect hypothalamic-pituitary-adrenal axis responsiveness. Because adolescence is a period of neurodevelopmental vulnerabilities and opportunities that may be especially sensitive to stress, it is imperative to more fully understand these interactions. Thus, we examined hormonal and neural responses in prepubertal (28 d of age) and adult (77 d of age) male rats after exposure to acute (30 min) or more chronic (30 min/d for 7 d) restraint stress. We report here that after acute stress, prepubertal males exhibited a significantly prolonged hormonal stress response (e.g. ACTH and total and free corticosterone) compared with adults. In contrast, after chronic stress, prepubertal males exhibited a higher response immediately after the stressor, but a faster return to baseline, compared with adults. Additionally, we demonstrate that this differential stress reactivity is associated with differential neuronal activation in the paraventricular nucleus of the hypothalamus, as measured by FOS immunohistochemistry. Using triple-label immunofluorescence histochemistry, we found that a larger proportion of CRH, but not arginine vasopressin, cells are activated in the arginine vasopressin in response to both acute and chronic stress in prepubertal animals compared with adults. These data indicate that experience-dependent plasticity of the hypothalamic-pituitary-adrenal neuroendocrine axis is significantly influenced by pubertal maturation.
Interference with 3′,5′-Cyclic Adenosine Monophosphate Response Element Binding Protein Stimulates Apoptosis through Aberrant Cell Cycle Progression and Checkpoint Activation
Authors: Dworet Jessica H. , Meinkoth Judy L.
Published: January 2006

We previously reported that protein kinase A activity is an important determinant of thyroid cell survival. Given the important role of cAMP response element binding protein (CREB) in mediating the transcriptional effects of protein kinase A, we explored whether interference with CREB family members impaired thyroid cell survival. Expression of A-CREB, a dominant-negative CREB mutant that inhibits CREB DNA binding activity, induced apoptosis in rat thyroid cells. A-CREB inhibited CRE-regulated gene expression but failed to alter the expression of bcl-2 family members or of well-characterized inhibitors of apoptosis. To elucidate the mechanism through which impaired CREB function triggered apoptosis, its effects on cell proliferation were examined. Expression of A-CREB inhibited cell number increases, in part due to delayed cell cycle transit. Protracted S-phase progression in A-CREB-expressing cells was sufficient to activate a checkpoint response characterized by Chk-1, histone H2A.X, and p53 phosphorylation. To determine whether cell cycle progression was required for apoptosis, the effects of p27 overexpression were investigated. Overexpression of p27 prevented cell cycle progression, checkpoint activation, and apoptosis in A-CREB-expressing cells. These data reveal a novel mechanism through which interference with CREB abrogates cell survival, through checkpoint activation secondary to cell cycle delay. This study may explain how interference with CREB induces apoptosis in cells where alterations in the expression of pro- and anti-survival genes are not detected.
NAADP, cADPR and IP3 all release Ca2+ from the endoplasmic reticulum and an acidic store in the secretory granule area
Authors: Gerasimenko Julia V. , Sherwood Mark , Tepikin Alexei V. , Petersen Ole H. , Gerasimenko Oleg V.
Published: January 2006

Inositol trisphosphate and cyclic ADP-ribose release Ca2+ from the endoplasmic reticulum via inositol trisphosphate and ryanodine receptors, respectively. By contrast, nicotinic acid adenine dinucleotide phosphate may activate a novel Ca2+ channel in an acid compartment. We show, in two-photon permeabilized pancreatic acinar cells, that the three messengers tested could each release Ca2+ from the endoplasmic reticulum and also from an acid store in the granular region. The nicotinic acid adenine dinucleotide phosphate action on both types of store, like that of cyclic ADP-ribose but unlike inositol trisphosphate, depended on operational ryanodine receptors, since it was blocked by ryanodine or ruthenium red. The acid Ca2+ store in the granular region did not have Golgi or lysosomal characteristics and might therefore be associated with the secretory granules. The endoplasmic reticulum is predominantly basal, but thin extensions penetrate into the granular area and cytosolic Ca2+ signals probably initiate at sites where endoplasmic reticulum elements and granules come close together.
Nitric oxide mediates neurodegeneration and breakdown of the blood-brain barrier in tPA-dependent excitotoxic injury in mice
Authors: Parathath Susana R. , Parathath Saj , Tsirka Stella E.
Published: January 2006

Stroke and many neurodegenerative diseases culminate in neuronal death through a mechanism known as excitotoxicity. Excitotoxicity proceeds through a complex signaling pathway that includes the participation of the serine protease tissue plasminogen activator (tPA). tPA mediates neurotoxic effects on resident central nervous system cells as well alters blood-brain barrier (BBB) permeability, which further promotes neurodegeneration. Another signaling molecule that promotes neurodegeneration and BBB dysfunction is nitric oxide (NO), although its precise role in pathological progression remains unclear. We examine here the potentially interrelated roles of tPA, NO and peroxynitrite (ONOO–), which is the toxic metabolite of NO, in BBB breakdown and neurodegeneration following intrahippocampal injection of the glutamate analog kainite (KA). We find that NO and ONOO– production are linked to tPA-mediated excitotoxic injury, and demonstrate that NO provision suffices to restore the toxic effects of KA in tPA-deficient mice that are normally resistant to excitotoxicity. NO also promotes BBB breakdown and excitotoxicity. Interestingly, BBB breakdown in itself does not suffice to elicit neurodegeneration; a subsequent ONOO–-mediated event is required. In conclusion, NO and ONOO– function as downstream effectors of tPA-mediated excitotoxicity.
Quality control of a mutant plasma membrane ATPase: ubiquitylation prevents cell-surface stability
Authors: Liu Yu , Chang Amy
Published: January 2006

The plasma membrane ATPase, Pma1, has remarkable longevity at the cell surface. In contrast to the wild-type protein, the temperature-sensitive mutant Pma1-10 is misfolded and undergoes rapid removal from the cell surface for vacuolar degradation. At the restrictive temperature, Pma1-10 becomes ubiquitylated before or upon arrival at the plasma membrane. Internalization from the plasma membrane and vacuolar degradation of Pma1-10 is dependent on the ubiquitin-interacting motif (UIM) of the epsin Ent1, suggesting recognition of ubiquitylated substrate by the endocytic machinery. Surprisingly, ubiquitylation of Pma1-10 is reversed when its internalization is blocked in an end3 mutant. Under these conditions, Pma1-10 acquires association with detergent-insoluble, glycolipid-enriched complexes (DIGs) which has been suggested to promote stability of wild-type Pma1. Ubiquitylation does not cause DIG exclusion because a Pma1-Ub fusion protein is not significantly excluded from DIGs. We suggest that ubiquitylation of Pma1-10 represents a component of a quality control mechanism that targets the misfolded protein for removal from the plasma membrane. Rapid internalization of Pma1-10 caused by its ubiquitylation may preempt establishment of stabilizing interactions.
Function Cultivation of Transparent Oxides Utilizing Built-In Nanostructure
Authors: Hosono Hideo , Kamiya Toshio , Hirano Masahiro
Published: January 2006

This review article describes recent progress in our research on cultivation of functionality in crystalline and amorphous transparent oxides utilizing nanostructures embedded in the material itself. It includes the background of our research and approach. Subjects included are material exploration and device application of transparent oxide semiconductors for transparent electronics, function emergence in nano-porous crystal 12CaO·7Al2O3 utilizing active anion species stabilized by sub-nanometer-sized cages, and modified silica glass for vacuum/deep ultraviolet lasers. Our description of each subject include: background and approach, material design concept, fabrication or modification method, properties, and device fabrication. Emphasis is placed on the importance of a variety of built-in nanostructures in transparent oxides for novel function realization and the high potential of transparent oxides as ingredients for an ubiquitous element strategy of material research in this century.
Preparation, Structure, and Characterization of a Novel Diphosphoheptadecatungstate Complex, [(P2O7)W17O51]4−
Authors: Himeno Sadayuki , Katsuta Tadashi , Takamoto Masayo , Hashimoto Masato
Published: January 2006

A novel diphosphoheptadecatungstate complex, [(P2O7)W17O51]4− was prepared from a 200 mM (M = mol dm−3) W(VI)–10 mM P2O74−–0.6 M HCl–40% (v/v) CH3CN system, and characterized by IR, UV–vis, 31P NMR, and 183W NMR spectroscopy, and voltammetry. Single-crystal X-ray analysis was made on [(C2H5)4N]4[(P2O7)W17O51]·CH3CN, which crystallized in the monoclinic space group P21/n, with cell parameters a = 16.1877(8), b = 22.103(1), c = 22.670(1) Å, β = 90.847(1)°, V = 8110.3(7) Å3, and Z = 4. The anion consists of a PW8O31 fragment derived from a β-Keggin-type [PW12O40]3− structure, and two PW8O31 units are linked by five oxygen atoms and a WO5 square pyramid. The [(P2O7)W17O51]4− anion exhibited a four-step reversible one-electron redox wave in CH3CN, and a three-step two-electron redox wave resulted in the presence of acid. This is the first example of an electrochemically-active diphosphotungstate complex.
Comparison of Basicity of the Diimine and Quinoid Group of 1,10-Phenanthroline-5,6-dione Ligated on Pt(II)
Authors: Okamura Rei , Fujihara Tetsuaki , Wada Tohru , Tanaka Koji
Published: January 2006

A platinum(II) complex bearing 1,10-phenanthroline-5,6-dione (phenO2), [PtCl(phenO2-N,N′)(PPh3)]+ ([2]+) was newly prepared and characterized. An X-ray crystallographic study of [2](PF6) revealed that the phenO2 ligand coordinates to platinum with the N,N′-chelate form. The basicity of the quinoid part of phenO2 in [2]+ and of the diimine one in [Pt(phenO2-O,O′)(PPh3)2] with an O,O′-chelate ring (3) was evaluated in the absence and the presence of Li+ by means of UV–vis spectroscopy and cyclic voltammetry. The quinoid group in [2]+ practically had no ability to bind Li+, but induced on anodic potential shift of the phenO2 localized redox potential by 850 mV due to the strong interaction between the reduced form of [2]+ and Li+. Undeniably, a weak interaction of Li+ with the diimine moiety of free phenO2 (K = 3.6 M−1) is greatly enhanced in the interaction between Li+ and the diimine site in 3 because of the electron donation from the catecholato group of the complex.
Steric and Electronic Effects of Substituents on Planar Nickel(II) Complexes: Synthesis, NMR Spectral and Single Crystal X-ray Structural Studies on Nickel(II) Dithiocarbamates with NiS2PN, NiS2PC, and NiS2P2 Chromophores
Authors: Arul Prakasam Balasubramaniam , Ramalingam Kuppukkannu , Bocelli Gabriele , Cantoni Andrea
Published: January 2006

Four new dithiocarbamatonickel(II) complexes [Ni(dchdtc)(NCS)(PPh3)] (1), [Ni(dchdtc)(CN)(PPh3)] (2), [Ni(dchdtc)(PPh3)2]ClO4 (3), and [Ni(dchdtc)(dppe)]ClO4 (4) (dchdtc = N,N-dicyclohexyldithiocarbamate anion, PPh3 = triphenylphosphine, and dppe = 1,2-bis(diphenylphosphino)ethane) were prepared from the parent [Ni(dchdtc)2]. All four complexes were analyzed by CV, UV–vis, IR, and NMR (1H, 13C, and 31P) spectra. 13C NMR spectra of the complexes (1–4) show the most notable >13CS2 signals at around 200 ppm. In the cyclohexyl ring, the α-CH carbon is deshielded to a greater extent on complexation. Extraordinary deshielding was observed for the 31P signal in all of the cases, indicating the effective bonding of phosphorus to the metal center. Single crystal X-ray structural analysis of the mixed ligand complexes (1–3) indicates a decrease in S–Ni–S bite angle when compared to that of the parent bis(dithiocarbamate), due to an increase in steric crowding around the central metal by the introduction of a bulky PPh3. The trans effects on Ni–S bonds can be arranged in the following order: NCS− < PPh3 < CN−. The S23, (1.306(3) Å), because of the steric effect exerted by two PPh3 groups and dchdtc. The observed negative reduction potentials follow the order: 1 > 2 > 3, indicating the presence of a higher relative electron density on 1 compared to 2 and 3.< bond is very short for complex
Structural Characterization of Copper(I) Complexes Supported by β-Diketiminate Ligands with Different Substitution Patterns
Authors: Shimokawa Chizu , Tachi Yoshimitsu , Nishiwaki Nagatoshi , Ariga Masahiro , Itoh Shinobu
Published: January 2006

Copper(I) complexes generated by using a series of β-diketiminate ligands (R1,R2LR3−, [(R3)N–C(R2)–C(R1)–C(R2)–N(R3)]−, see Chart 1; “β-diketiminate” denotes enaminone imine analogs) have been structurally characterized by X-ray crystallographic analysis. In the α-nitro-ligand system (R1 = NO2 and R2 = H), the structure of the resulting products were largely affected by the nitrogen substituent R3, providing bis(β-diketiminato)copper(II) complex 1 [a product of the disproportionation reaction of copper(I)] (R3 = Ph), head-to-tail linear coordination polymer copper(I) complex 2 (R3 = Mes, (mesityl)), and mononuclear copper(I) complex 3 (R3 = Dipp (2,6-diisopropylphenyl)). On the other hand, α-cyano-ligand (R1 = CN and R2 = H or Me) always gave head-to-tail coordination polymer copper(I) complexes (4–8) regardless of the aromatic substituent R3. In both systems, β-diketiminate ligands exhibited a U-shaped closed conformation, forming a six-membered chelate ring with copper(I). Copper(I) complexes with a β-diketiminate ligand with a W-shaped open conformation were also obtained in the case of α-methyl and α-hydrogen derivatives (R1 = Me or H, R2 = H, and R3 = Dipp). In these cases, the dinuclear and tetranuclear copper(I) macrocyclic complexes 9 and 10 were obtained.
Intermolecular Association Model of Antifungal Polyene Macrolide via Concerted =C–H···O Interactions: X-ray Crystal Structure Analysis and Ab Initio Molecular-Orbital Calculations of Chainin
Authors: In Yasuko , Ohishi Hirofumi , Miyagawa Hiroo , Kitamura Kunihiro , Igarashi Yasuhiro , Ishida Toshimasa
Published: January 2006

The absolute configuration of chainin (1), a polyene macrolide antibiotic, was determined by X-ray crystal analyses, and the conformational stability of planar 28-membered ring was confirmed by an ab initio quantum chemical calculation. The most prominent feature observed in the crystal structure was the concerted =C–H···O interactions formed between four conjugated olefinic CH groups and five hydroxyl oxygen atoms of neighboring molecules. The character of the interaction was investigated by IR measurements and quantum chemical calculations, leading to the conclusion that these concerted interactions are powerful enough to form defined intermolecular association of polyene macrolide. Characteristically, this intermolecular association mode allows the proposal of a barrel-stave assembly, comprising eight parallel or antiparallel pairs of 1 via =C–H···O interactions, which serves as a possible ion-permeable membrane channel structure of polyene macrolide, which may be responsible for the antifungal activity in cell membranes.
Total Synthesis, Structural Revision, and Biological Evaluation of Calafianin, a Marine Spiroisoxazoline from the Sponge, Aplysina gerardogreeni
Authors: Ogamino Takahisa , Obata Rika , Tomoda Hiroshi , Nishiyama Shigeru
Published: January 2006

The reported structure of the natural calafianin (1) and its isomer in the epoxide region 13 were successfully synthesized through the cis- and trans-spiroisoxazoline compounds, which were produced by electrochemical oxidation of the hydroxyimino-phenol derivative 7, followed by Zn[BH4]2 reduction. Comparison of the spectroscopic data of the synthetic (±)-1 and (±)-13 resulted in structural revision of the natural calafianin to 13, possessing the trans-relationship between an epoxide and an oxygen of the isoxazoline. In addition, a significant difference of antimicrobial activity between 1 and 13 is discussed.
CsOH·H2O Promoted Areneselenenylation of Aryl Bromides and Iodides
Authors: Varala Ravi , Ramu Enugala , Adapa Srinivas R
Published: January 2006

We report a transition metal-free synthetic protocol for the cross-coupling reaction of aryl bromides and aryl iodides and diphenyl diselenide (Ph2Se2) using CsOH·H2O as a base in DMSO at 110 °C. Using this protocol, we show that a variety of diaryl selenides can be synthesized in moderate to good yields.
Direct and Convenient Synthesis of [Bis(trifluoroacetoxy)iodo]arenes from Iodoarenes
Authors: Hossain Md Delwar , Kitamura Tsugio
Published: January 2006

An easy, safe, and effective method for preparing [bis(trifluoroacetoxy)iodo]arenes, ArI(OCOCF3)2, in high yields from some iodoarenes are reported, using a K2S2O8/CF3COOH/CH2Cl2 system. This procedure avoids the use of high temperature and severe reaction conditions.
Decomposition of Chlorobenzene over Phosphate and Sulfate Catalysts Properties
Authors: Takita Yusaku , Sadatomi Yoshitaka , Nishiguchi Hiroyasu , Nagaoka Katsutoshi
Published: January 2006

The catalytic conversion of chlorobenzene (CB) over some metal phosphates and sulfate was studied in the presence of water vapor and oxygen. The conversion of CB proceeded in the order of AlPO4, Zr3(PO4)4, CePO4–AlPO4, and La2(SO3)3 above 673 K. The major products were CO, CO2, and HCl. The reaction proceeded in the absence of water vapor; however, the activity was greatly reduced in the absence of oxygen. Even in the presence of oxygen, 30 mol % of water vapor inhibited the reaction. No intermediate hydration products were observed. There was no correlation between each of the catalytic activity, the acidity, and the concentration of the surface hydroxys of the catalysts. These results suggest that the essential reaction for CB conversion is oxidation. The specific surface area (SSA) of the catalysts was not changed during the CB conversion.
Nano-Tribological Study on the Smoothness of Writing with a Ball-Point Pen Using Friction Force Microscopy
Authors: Okuo Hiroyasu , Asahi Toru , Onoue Takahiro , Osaka Tetsuya
Published: January 2006

The relationship between human sensation experienced in the use of a material and its physical properties was investigated for the case of writing with a ball-point pen containing water-based ink. Friction force microscopy (FFM) and a writing tester were used to measure friction in nano- and macro-scale, respectively, and their results were correlated with the smoothness of the act of writing. FFM allowed the determination of the optimum concentration of a specific lubricant to be incorporated in the ink to minimize the wear of the bearing material, although no significant relationship was observed with the writing tester. The nano-tribological measurements by FFM provide a significant means to understand the relationship between materials and the smoothness of the act of writing.
Improvement of Electrochemical Capability of Sputtered Silicon Film Anode for Rechargeable Lithium Batteries
Authors: Komaba Shinichi , Mikami Fuminobu , Itabashi Tatsuya , Baba Mamoru , Ueno Taku , Kumagai Naoaki
Published: January 2006

To improve the electrochemical properties of the silicon film anode in lithium cells, we prepared three types of silicon based-films, i.e., intrinsic silicon, n-type silicon, and Ag10Si90 binary films using r.f. magnetron sputtering. Based on galvanostatic charge–discharge tests and a.c. impedance measurements, the n-type silicon film and Ag10Si90 binary film cells exhibited a superior cycle life and lower electrochemical resistance compared with the intrinsic silicon film cell. The potential variation in the electrochemical alloying/de-alloying reactions of the Ag10Si90 binary film with lithium was different from that of the intrinsic silicon film, meaning that the Ag ingredient in the binary film affected the charge–discharge reaction. Furthermore, when a Ni plate roughened by chemical etching was used as a substrate, the Ag10Si90 film anode demonstrated an excellent capacity retention during 400 cycles with a high discharge capacity of >200 μA h cm−2 (corresponding to 1500 mA h g−1) at 0.5 mA cm−2 (2.5 C).
Physico-Chemical Properties of New Liquid Crystals Incorporating a Benzofuran-2-one Skeleton
Authors: Morita Yuki , Zhang Fusheng , Tasaka Takeyasu , Yamaguchi Remuto , Okamoto Hiroaki , Takenaka Shunsuke
Published: January 2006

The liquid crystal properties of 3H-2-oxobenzofuran-6-yl 4-(n-CnH2n+1O)benzoates (1-n, n = 5–12), 4′-(n-CnH2n+1O)biphenyl-4-carboxylates (2-n, n = 6–10), and 4-(n-CnH2n+1)benzoates (3-n, n = 4–6) are described. The n = 5–8 homologues of 1-n exhibit a nematic (N) phase, and the n = 8–12 homologues exhibit a smectic A (SmA) phase, where the layer spacing is ca. 1.3 times of the calculated molecular length. The homologues of 2-n show a complex phase-transition behavior involving a smectic C (SmC), two kinds of SmA, reentrant nematic, and N phases, where the SmC phase is exhibited by the n = 6–8 homologues. The layer spacings of SmA phases formed at high and low temperature regions correspond to 1.3 and 1.0 times of the molecular lengths, respectively. The polar interactions around the terminal lactone moiety are assumed to play important roles for the complex polymesomorphism and diversity of the smectic layer structure.
Synthesis, Properties, and Application as Emitters in Organic Electroluminescence Devices of Quinacridone- and Squarylium-Dye-Centred Dendrimers
Authors: Matsui Masaki , Tanaka Saori , Funabiki Kazumasa , Kitaguchi Toru
Published: January 2006

The UV–vis absorption and fluorescence spectra, solubility, and application as emitters in single-layer organic electroluminescence (EL) devices of novel quinacridone- and squarylium-dye-centred dendrimers (Gn-QAs and Gn-SQs) were examined. The respective dendrimers showed no remarkable differences in the UV–vis absorption (λmax) and photoluminescence (PL) maxima (λem). The solubility of dendrimers drastically increased at higher generation. The EL maxima of Gn-QAs and Gn-SQs were observed at 522 and 710 nm, respectively. In the case of Gn-QAs, the EL intensity under the fixed bias voltage decreased at higher generation due to a decrease in energy transfer from the host molecules to QA. Meanwhile, in the case of Gn-SQs, the EL intensity increased upon higher generation because of increased current density and the improvement of concentration quenching.
Multi-Dimensional Crystal Structures and Unique Solid-State Properties of Heterocyclic Thiazyl Radicals and Related Materials
Authors: Awaga Kunio , Tanaka Toshiyuki , Shirai Takahiro , Fujimori Masato , Suzuki Yosuke , Yoshikawa Hirofumi , Fujita Wataru
Published: January 2006

The crystal structures and magnetic properties of heterocyclic thiazyl radicals and related materials have been examined. TTTA (=1,3,5-trithia-2,4,6-triazapentalenyl) exhibited a first-order phase transition between a paramagnetic high-temperature (HT) phase and a diamagnetic low-temperature (LT) phase, with a wide thermal hysteresis loop over the temperature range 230–305 K. The phase control of TTTA was achieved by pressure and by light irradiation. BDTA (=1,3,2-benzodithiazolyl) also exhibited a diamagnetic–paramagnetic phase transition above room temperature. However, fresh samples always exhibited a superheating of the LT phase that resulted in a double melting (melt–recrystallization–melt process) and supercooling of the HT phase, which in turn led to an antiferromagnetic ordering at 11 K. The molecular compounds of thiazyl radicals were prepared; TTTA formed a coordination polymer structure in the TTTA·[Cu(hfac)2 (=bis(hexafluoroacetylacetonato)–copper(II))] crystal, where a ferromagnetic coupling was found between the organic and inorganic species. The cation radical salts, [BBDTA (=benzo[1,2-d:4,5-d′]bis[1,3,2]dithiazole)]·MCl4 (M = Ga and Fe), exhibited ferromagnetic ordering at 7 K and ferrimagnetic ordering at 44 K after evaporation of crystal solvents. We also grew crystals of M–TTDPz (TTDPz = tetrakis(thiadiazole)porphyrazine and M = H2, Fe, Co, Ni, Cu, and Zn) and performed their structural analyses. Their crystal structures were found to depend strongly on the central metal ion and could be classified into three forms: α, β, and γ.
Design and Synthesis of Bis(Zn(II)–Dipicolylamine)-Based Fluorescent Artificial Chemosensors for Phosphorylated Proteins/Peptides
Authors: Ojida Akio , Hamachi Itaru
Published: January 2006

Protein phosphorylation represents a ubiquitous mechanism for controlling diverse protein functions and plays central role in signal transduction cascades in living cells. In order to elucidate the complex network of phosphorylation-based signaling, it is desirable to develop versatile methods and molecular probes that can selectively recognize and detect the phosphoprotein of interest. We present herein the molecular recognition and fluorescence sensing of phosphorylated proteins/peptides by synthetic small molecules. The chemosensors are designed to utilize metal–ligand interaction as a main binding force and thus possess two Zn(II)–dipicolylamine(dpa)s as the binding sites for phosphate group(s) on the protein/peptide surface. We propose the two strategies for recognition of phosphorylated protein/peptide surface; (i) cooperative-binding strategy and (ii) cross-linking strategy. The binuclear anthracene-type chemosensors are designed to interact with a phosphate group on protein/peptide surface based on the cooperative-binding mode, in which the single phosphate group is recognized by the two Zn(II)–dpa sites of the chemosensor. The binding affinity of the chemosensors sensitively depends on the sequence of the phosphopeptide, and reaches to nearly 107 M−1 for a highly negatively charged peptide. In addition, the chemosensors increase their fluorescence upon binding to the phosphorylated proteins/peptides. Therefore, they can distinguish between phosphorylated and non-phosphorylated state of proteins/peptides by their fluorescence intensities. Detailed experiments clarify that the phosphate anion-assisted binding of the second Zn(II) to the binuclear chemosensors is crucial for the fluorescence increase upon binding to the phosphorylated derivatives. The other approach to recognize phosphorylated protein surface by synthetic small molecule is based on the cross-linking strategy. The chemosensors possess bipyridine as a spacer unit between two Zn(II)–dpa sites, which are arranged at appropriately distal position, thereby make possible the cross-linking interaction with two phosphate groups on protein surface. The chemosensors shows higher affinity for the bis-phosphorylated peptide than for the mono-phosphorylated one, indicating that the cross-linking interaction is effective for recognition of multisite phosphorylation domains of a protein. The results presented in this article are regarded as the first step toward detection of specific phosphorylation event of a protein in complicated biological systems using synthetic small molecules. The bioanalytical application of these chemosensors, such as the fluorescence detection of phosphatase catalyzed dephosphorylation and the selective staining of phosphoprotein in SDS-PAGE, are also discussed.
Electromagnetophoretic Measurements of Adsorption Forces of Polystyrene Microparticles on Silica Surfaces in Surfactant Solutions
Authors: Iiguni Yoshinori , Watarai Hitoshi
Published: January 2006

An electromagnetophoretic force has been applied for the measurement of the adsorption force of a single polystyrene particle to a silica surface in electrolyte solutions. By the electromagnetophoretic buoyancy, polystyrene microparticles in a fused-silica capillary were made to migrate perpendicular to the wall of the capillary. A switching of the current direction and a gradual increase of the current under a homogeneous magnetic field of 10 T could desorb the single particle from the wall and allowed us to measure the adsorption force from the desorbing current with a sensitivity of pN. By this method, the adsorption forces of polystyrene particles on a bare surface and on a squalane-coated fused-silica surface were measured in the absence and the presence of surfactants such as Triton X-100, cetyltrimethylammonium bromide, and sodium dodecyl sulfate. The observed adsorption forces showed that the roles of the surfactants included not only the reduction of the adsorption force as a spacer, but also the production of a characteristic force due mainly to electrostatic interaction.
DFT Calculations of Cubane-Type Mo2Ru2S4 Clusters. Stability of a Possible Dinitrogen Cluster and an Isolable Acetonitrile Cluster
Authors: Yoshizawa Kazunari , Kihara Naoki , Shiota Yoshihito , Seino Hidetake , Mizobe Yasushi
Published: January 2006

The electronic properties of cubane-type mixed-metal sulfido clusters with an Mo(V)2Ru(II)2S4 core and possible dinitrogen activation on it are described from DFT computations. The cluster [(CpRu)2{MoCl2(MeCN)}2(μ3-S)4] (Cp = η5-C5H5), whose Cp* analogue (Cp* = η5-C5Me5) was isolated and fully characterized by X-ray crystallographic analysis, has a closed-shell singlet ground state. Upon release of the acetonitrile ligands, the ground state remains in a closed-shell singlet state, the corresponding open-shell singlet and triplet states lying 2 kcal mol−1 above the closed-shell singlet state. Dinitrogen can hardly coordinate to this neutral [(CpRu)2(MoCl2)2(μ3-S)4] cluster. However, upon reduction by two electrons the binding energy for two N2 molecules to the resultant anionic cluster [(CpRu)2{MoCl2(N2)}2(μ3-S)4]2− increases to 4 kcal mol−1. This interaction, which still seems too weak to become isolable, is analyzed in terms of molecular orbitals to increase our understanding of dinitrogen activation by synthetic systems. The HOMO of [(CpRu)2(MoCl2)2(μ3-S)4]2− is pointing toward missing ligands and can interact effectively with the πg* orbitals of dinitrogen. This orbital might play a role in the binding of dinitrogen.
Self-Organization Properties and Microstructures of Sodium N-(11-Acrylamidoundecanoyl)-l-valinate and -l-threoninate in Water
Authors: Roy Sumita , Dey Joykrishna
Published: January 2006

A new class of N-acylamino acid surfactants, sodium N-(11-acrylamidoundecanoyl)-l-valinate (SAUV) and -l-threoninate (SAUT), were synthesized and characterized in aqueous solutions. The self-assembly properties were studied by surface tension, fluorescence probe, light scattering, and microscopic techniques. The interfacial properties of the amphiphiles have been investigated at the air/water interface. The critical aggregation concentration (cac) and free energy change of aggregation for both amphiphiles were determined. The results of fluorescence probe and surface tension studies have indicated that initially flat bilayer structures are formed, which upon a further increase of surfactant concentration transform into closed vesicles. The pH and temperature dependence of the bilayer aggregates have been studied. The role of intermolecular hydrogen bonding between amide groups upon aggregation towards microstructure formation in solution has been elucidated. The micropolarity of the hydrophobic domains of the bilayer self-assemblies was estimated by fluorescence probe methods. Dynamic light scattering measurements were performed to determine the mean size of the aggregates. The circular dichroism spectra of SAUV and SAUT suggested the formation of chiral aggregates in dilute solution. The transmission electron micrographs revealed the presence of closed vesicles and twisted ribbons in the aqueous solutions of the amphiphiles. Optical microscopic images also showed the existence of twisted ribbons and rope-like helical structures in the case of SAUV.
Doppler-Free Two-Photon Excitation Spectroscopy and the Zeeman Effect in the “Channel Three” Region of C6H6
Authors: Baek Dae Youl , Chen JinHai , Wang Jinguo , Doi Atsushi , Kasahara Shunji , Baba Masaaki , Katô Hajime
Published: January 2006

Doppler-free two-photon excitation spectra and the Zeeman effects for the 1021401 and 1011401 bands, whose vibrational excess energies are 3412 and 2492 cm−1, respectively, of the S11B2u ← S01A1g transition in gaseous benzene-h6 have been measured. Rotationally resolved lines up to a rotational excess energy of 945 cm−1 in the 1011401 band, whose excess energy is isoenergetic with the one of the 1021401 band at low J, have been observed. The density of perturbation is observed to increase around the K = 0 and K = J levels in the 1011401 band as the rotational energy increases, but line broadening is not observed. It was reported that only the K = 0 lines at low J and the K = J lines at high J were observed as a sharp line and the rest was washed out by broadening in the 1021401 band. The assignments are confirmed by the Zeeman spectra. The character and magnitude of Zeeman splittings in both bands could be understood as originating from the electronic orbital angular momentum arising from a mixing of the S11B2u and S21B1u states via J–L coupling. The levels of the S11B2u state are found not to be mixed with a triplet state by the Zeeman effect.
Kinetic Study of Synthesizing Bisphenol A Diallyl Ether in a Phase-Transfer Catalytic Reaction
Authors: Wang Maw-Ling , Lee Ze-Fa
Published: January 2006

In the synthesis of bisphenol A diallyl ether from bisphenol A and allyl bromide, the liquid–liquid mode of operation catalyzed by quaternary ammonium salts was carried out in an alkaline solution/organic solvent two-phase medium. The mono-substituted product was not detected during or after the reaction. In this work, a rational reaction mechanism is proposed and a kinetic model then established. The apparent rate constant of the organic-phase reaction was obtained from experimental data. The effects of the reaction conditions, including agitation speed, organic solvents, quaternary ammonium salts, inorganic salts, temperature, alkali compounds, amount of potassium hydroxide, and water on the conversion of allyl bromide, were investigated in detail. The presence of a small amount of tetrabutylammonium bromide (TBAB) in the chlorobenzene/water system produced a rate over several folds larger than that of the reaction system in the absence of phase-transfer catalyst. The presence of alkali compounds promoted the formation of alkoxide and enhanced the extractive efficiency due to the salting out effect. The present etherification via phase-transfer catalyst could operate at lower temperatures to avoid Claisen rearrangement, which usually occurs at higher temperatures. Rational reasons to account for the absence of mono-substituted product are explained satisfactorily. Peculiar phenomena in investigating the effects of the volume of organic solvent, amount of KOH, and the volume of water and alkali compounds on the apparent rate constants are also explained.
Thermodynamics of Ion-Exchange of Alkali Metal Ions on Crystalline Niobium(V) Phosphate
Authors: Ahmad Anees , Rafatullah Mohd , Danish Md
Published: January 2006

Exchange isotherms for hydrogen ion/alkali metal ions (H+/Li+, H+/Na+, H+/K+, H+/Rb+, and H+/Cs+) have been studied at 20, 40, and 60 °C at a constant ionic strength of 0.1 on the crystalline phase of niobium(V) phosphate. The isotherms show an irregular (S-shaped) behavior without a phase transition. A selectivity reversal has been observed over the entire system of solid compositions. Plots of the selectivity coefficient (loge scale) versus equivalent ionic fraction of metal ion in the exchanger phase are linear for all of the systems and at all temperatures studied. The ion-exchange capacities and the maximum uptake at equilibrium is on the order of Li+ < Cs+ < Rb+ < Na+ < K+. The higher selectivity of potassium ion compared to other alkali ions has been explained in terms of steric hindrance and the stiff three-dimensional structure of the exchanger having a fixed pore size. The thermodynamic parameters for the overall and for zero loading have been worked out using the Gaines–Thomas equation.
Thermo-Responsive Polymer-Mediated Extraction Followed by Flotation for the Removal of Poly(aromatic hydrocarbons) from Gases
Authors: Saitoh Tohru , Mizutani Koji , Hiraide Masataka
Published: January 2006

A simple and efficient gas decontamination system has been developed. The method is based on the aeration of an aqueous solution of a thermo-responsive polymer and polymer-mediated extraction followed by flotation. Polyaromatic hydrocarbons (PAHs) in gas phase were dissolved by aeration through the aqueous solution of a water-soluble polymer, poly(N-isopropylacrylamide) [PNIPAAm], containing 0.1 mol dm−3 sodium nitrate and 1% (v/v) ethanol. The efficiency of the dissolution increased with increasing PNIPAAm concentration. PAHs consisting of more than 3 aromatic rings were quantitatively collected in the polymer solution, while the collection of volatile naphthalene was insufficient. Subsequently, on heating the polymer solution to 50 °C, the polymer media incorporating PAHs formed precipitates. The precipitates were floated to the surface of water by bubbling. Hydrophobic PAHs, such as pyrene and benzo[a]pyrene, were highly concentrated into the polymer phase having a very small volume.
Serum Tumor Markers in Breast Cancer: Are They of Clinical Value?
Authors: Duffy Michael J
Published: January 2006

Background: Although multiple serum-based tumor markers have been described for breast cancer, such as CA 15-3, BR 27.29 (CA27.29), carcinoembryonic antigen (CEA), tissue polypeptide antigen, tissue polypeptide specific antigen, and HER-2 (the extracellular domain), the most widely used are CA 15-3 and CEA.

Methods: The literature relevant to serum tumor markers in breast cancer was reviewed. Particular attention was given to systematic reviews, prospective randomized trials, and guidelines issued by expert panels.

Results: Because of a lack of sensitivity for early disease and lack of specificity, none of the available markers is of value for the detection of early breast cancer. High preoperative concentrations of CA 15-3 are, however, associated with adverse patient outcome. Although serial determinations of tumor markers after primary treatment for breast cancer can preclinically detect recurrent/metastatic disease with lead times of ∼2–9 months, the clinical value of this lead time remains to be determined. Serum markers, however, are the only validated approach for monitoring treatment in patients with advanced disease that cannot be evaluated by use of conventional criteria.

Conclusions: CA 15-3 is one of the first circulating prognostic factors for breast cancer. Preoperative concentrations thus might be combined with existing prognostic factors for predicting outcome in patients with newly diagnosed breast cancer. At present, the most important clinical application of CA 15-3 is in monitoring therapy in patients with advanced breast cancer that is not assessable by existing clinical or radiologic procedures.