bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pair-Selective Coupling of Alkynes with Alkenes on Zirconocene Complex
Authors: Takahashi Tamotsu , Xi Zhenfeng , Rousset Christophe J , Suzuki Noriyuki 
Published: April 2006

Abstract
When ethylene and alkynes such as 4-octyne and diphenylacetylene were treated with Cp2ZrBu2 highly pair selective coupling products were formed in high yields. Similarly, styrene or trimethylvinylsilane also afforded cross coupling products with alkynes on zirconocene complex.
A Novel Antimicrobial Substance in Etiolated Seedlings of Adlay
Authors: Ishiguro Yukio , Okamoto Kenji , Ojima Fumihiro , Sonoda Youji 
Published: April 2006

Abstract
A novel antimicrobial substance was isolated from the extract of etiolated seedlings of Adlay (Coix lachryma-jobi L. var. ma-yuen Stapf). This substance showed antimicrobial activity against bacteria, but no activity against yeast and fungi.
Skeletal Isomerization of n-Butane Catalyzed by an Acidic Cesium Salt of 12-Tungstophosphoric Acid
Authors: Na Kyutae , Okuhara Toshio , Misono Makoto 
Published: April 2006

Abstract
A salt of H3PW12O40, Cs2.5H0.5PW12O40, catalyzed efficiently the skeletal isomerization of n-butane to isobutane at 300 °C. The activity and selectivity were much higher than those of SO22−/ZrO2. H-ZSM-5 was more active than Cs2.5H0.5PW12O40, but the selectivity was very low.
Observation of Highly Endoergic Chemiluminescent Reactions on Laser Ablation of Metals. Detection of AlH (A1Π), AlN (A3Πi), AlO (B2Σ+) and MgO (B1Σ+) in Al + NH3, Al + H2O, and Mg + O2 Systems
Authors: Ishitani Eizi , Yoshimoto Satoshi , Higashide Hiroshi , Kobayashi Makoto , Shinohara Hisanori , Sato Hiroyasu 
Published: April 2006

Abstract
Occurrence of highly endoergic chemiluminescent reactions was observed using laser ablation of metal targets for Al + NH3, Al + H2O and Mg + O2 systems. Observed chemiluminescent species were AlH (A1Π), AlN (A3Πi), AlO (B2Σ+) and MgO (B1Σ+).
Effects of Solvent Molecular Size on Dissociation Rates of the N–H Bond in Ammonium Salts Derived from Tertiary Amines
Authors: Oki Michinori , Matsusaka Michio , Mishima Hirohito , Toyota Shinji 
Published: April 2006

Abstract
Rates of dissociation of the N–H bond in ammonium salts derived from tertiary amines were found to be enhanced in solvents of which molecular size is large with respect to those in solvents of small molecular size, if polarities of the solvents are about the same. The effects are attributed to the weak solvation by the solvents of large molecular size which is associated with small positive entropy of activation. Thus the third aspect of solvent effects, bulkiness of solvent molecules, is proposed.
Generation of Alkyl Radicals from 1-Oxidoalkylidenechromium(0) Complexes by Oxidation with Manganese(III) 2-Pyridinecarboxylate and Their Reactions with Olefins
Authors: Narasaka Koichi , Sakurai Hidehiro 
Published: April 2006

Abstract
Tetramethylammonium pentacarbonyl(1-oxidoalkylidene)chromium(0) complexes, prepared from the corresponding carbanion and hexacarbonylchromium(0), are oxidized with manganese(III) 2-pyridinecarboxylate to generate carbon-centered radicals which react with various olefins giving the intermolecular addition products.
Extraordinary Large Red Shift of the n(Si)→3p(Si) Transition of Silylenes Caused by Trimethylsilyl and Trimethylgermyl Substituents
Authors: Kira Mitsuo , Maruyama Toyotaro , Sakurai Hideki 
Published: April 2006

Abstract
The n(Si)→3p(Si) absorption maxima of silylenes were shifted significantly red by introducing trimethylsilyl and trimethylgermyl substituents. The origin of the substituent effects will be attributed to the σ-electron donating ability of the trimethylmetal groups which lift the energy level of n(Si) orbital significantly.
Migration of the Hydroxyl Group of N-Hydroxy-N-phenylamides to the Phenyl Group with Tertiary Phosphines and Tetrachloromethane. A Novel Transhydroxylation Reaction
Authors: Kikugawa Yasuo , Mitsui Kimiyo 
Published: April 2006

Abstract
The hydroxyl group of N-hydroxy-N-phenylamides rearranges mainly to the ortho position of the N-phenyl ring by the system (n-Bu)3P-CCl4-CH3CN; use of less than a stoichiometric amount of (n-Bu)3P is effective for this reaction.
Abrupt Conversion of Mixed-Valence State in Trinuclear Iron Cyanoacetate Complex
Authors: Nakamoto Tadahiro , Katada Motomi , Kawata Satoshi , Kitagawa Susumu , Kikuchi Kouichi , Ikemoto Isao , Endo Kazutoyo , Sano Hirotoshi 
Published: April 2006

Abstract
The crystal structure of newly synthesized trinuclear iron cyanoacetate complex, [Fe3O(NCCH2CO2)6(H2O)3], has been determined by single-crystal X-ray structure analysis and found to have a three-dimensional hydrogen-bond network. The temperature dependence of Mössbauer spectrum shows that the complex converts from a valence-trapped state to a valence-detrapped state within a 10 K range.
Partial Oxidation of Methane Using the Redox of Cerium Oxide
Authors: Otsuka Kiyoshi , Ushiyama Tetsuya , Yamanaka Ichiro 
Published: April 2006

Abstract
Direct conversion of methane into synthesis gas of H2/CO ratio of 2 has been demonstrated using CeO2 as an oxidant at 873–1073 K. The reaction was accelerated in the presence of Pt black (1 wt%). The reduced cerium oxide after the oxidation of methane can be used to convert carbon dioxide into carbon monoxide.
Novel Preparation, Characterization and Catalytic Properties of Polymer-Protected Cu/Pd Bimetallic Colloid
Authors: Toshima Naoki , Wang Yuan 
Published: April 2006

Abstract
Polymer-protected Cu/Pd bimetallic colloids with different atomic ratio of Cu to Pd were successfully prepared by refluxing a glycol solution of hydroxide of copper and palladium in the presence of poly(N-vinyl-2-pyrrolidone). The TEM, XRD, AAS and UV-vis spectrum measurements indicate the formation of bimetallic alloy phase in the bimetallic colloids. High catalytic activity and selectivity for the hydration of acrylonitrile to acrylamide was achieved by using the Cu/Pd(Cu/Pd = 2) bimetallic colloid as a catalyst.
Long-lived Charge Separated States from Zinc Porphyrin-Free Base Porphyrin-Diimide-Quinone Tetrads
Authors: Osuka Atsuhiro , Zhang Run-Ping , Maruyama Kazuhiro , Ohno Takeshi , Nozaki Koichi 
Published: April 2006

Abstract
Tetrads consisting of zinc porphyrin (ZnP), free base porphyrin (H2P), naphthalene-1,4,5,8-tetracarboxylic diimide (NIm), and quinone (Q) were synthesized. Upon photoexcitation, these tetrads provide ion pair states (ZnP)+-H2P-NIm-(Q)−, whose lifetimes are much longer, reaching more than 100 μs in THF-butyronitrile, in biphenyl-bridged models but shorter in diphenylmethyl-bridged models in comparison to the corresponding Q-free triads.
Chiral Synthesis of (−)-Colletol Based on Palladium-Catalyzed Reductive Cleavage of Alkenyloxiranes with Formic Acid
Authors: Shimizu Isao , Omura Tetsuya 
Published: April 2006

Abstract
Total synthesis of (−)-colletol was achieved using palladium-catalyzed hydrogenolysis of optically active (E)-4,5-epoxy-2-alkenoates to (E)-5-hydroxy-2-alkenoates with formic acid as a key step for preparation of the intermediate hydroxy ester segments.
The Catalytic Reduction of Aldehydes and Ketones with 2-Propanol over Silica-Supported Zirconium Catalyst
Authors: Inada Kazushige , Shibagaki Makoto , Nakanishi Yukio , Matsushita Hajime 
Published: April 2006

Abstract
Reduction of aldehydes and ketones with 2-propanol proceeded efficiently over silica-supported zirconium catalyst, and the corresponding alcohols were obtained in high yields. In the reduction of aldehyde, the acetalization did not occur and the side reaction, the aldol condensation, was inhibited.
“Elasticity Index” for the Connecting Groups of Double-Chain Amphiphiles Bearing Two Hydrophilic Groups
Authors: Masuyama Araki , Kawano Tomoko , Zhu Yun-Peng , Kida Toshiyuki , Nakatsuji Yohji 
Published: April 2006

Abstract
The surface pressure-area (π-A) isotherms for a series of double-chain diols derived from diepoxides were measured. A new parameter, “Elasticity Index”, is proposed to explain the effect of the connecting group between the two lipophilic chains of double-chain amphiphiles on the behavior of their monolayer films at the air-water interface.
Alignment by Poling and Regioselective Photodimerization of Stilbazolium Ions Dispersed in Polyelectrolytes
Authors: Takagi Katsuhiko , Shibata Shigeyuki , Oguri Sachiko , Sawaki Yasuhiko , Suzuoki Yasuo , Segi Takeshi 
Published: April 2006

Abstract
4-(N,N-Dimethylamino)stilbazolium ion dispersed in thin films of poly(styrenesulfonates) (PSS) or copolymer of poly(ethylene and maleates) (PEcoMA) was shown to be aligned by electric field poling on the basis of the resulting photodimerization giving the syn-head-to-head dimers.
Mechanism of Photochemical Reaction of Contact Charge Transfer Pair between 1,1-Diarylethene and Oxygen
Authors: Kojima Masanobu , Ishida Akito , Takamuku Setsuo 
Published: April 2006

Abstract
Selective excitation of the contact charge transfer band between 1,1-diarylethene and oxygen in dichloromethane and acetonitrile gave 3,3,6,6-tetraaryl-1,2-dioxane and benzophenone derivative through an electron transfer reaction. The proposed mechanism was confirmed by the direct observation of the dimer cation radical of the olefin trapped by a triplet oxygen in pulse radiolysis.
Transition Metal Catalyzed Reaction of Peralkylated 3,4-Bis(alkylidene)-1,2-disilacyclobutane
Authors: Kusukawa Takahiro , Kabe Yoshio , Ando Wataru 
Published: April 2006

Abstract
Peralkylated 3,4-bis(alkylidene)-1,2-disilacyclobutanes prepared by convenient synthetic route were quantitatively converted to 3,4,7,8-tetrakis(alkylidene)-1,2,5,6-tetrasilacyclooctane (twist and chair 1:1 mixture) by Pd-catalyzed reaction. In the presence of unsaturated compounds, this disilane metathesis reaction was inhibited to give double silylation products. The reaction pathways are highly dependent upon electronic factors of unsaturated compounds and the catalyst.
Quantification of Biochemical Markers of Bone Turnover by Kinetic Measures of Bone Formation and Resorption in Young Healthy Females
Authors: Weaver Connie M. , Peacock Munro , Martin Berdine R. , McCabe George P. , Zhao Jian , Smith David L. , Wastney Meryl E. 
Published: April 2006

Abstract
The quantification of biochemical markers of bone formation and resorption with kinetic measures of bone turnover is an essential step in their validation. Some biochemical markers have been validated by quantification against formation and resorption rates measured by calcium kinetics in adults with bone disease. However, none has been validated in healthy individuals who are undergoing skeletal growth and bone consolidation. Therefore, we have measured biochemical markers of bone formation (serum osteocalcin [OC], bone-specific alkaline phosphatase [BAP], and total alkaline phosphatase [ALP]) and resorption (serum tartrate resistant acid phosphatase [TRAP], urinary cross-linked N teleopeptides of type I collagen/creatinine [NTx/Cr], and hydroxyproline/creatinine [OHP/Cr]) in healthy females aged 11–32 years (n = 31) after an overnight fast to determine their relationship with bone formation (Vo+) and bone resorption (Vo−) as measured by calcium kinetics and balance. All biochemical markers were highly intercorrelated (r &gt; 0.6, p &lt; 0.001) as were Vo+ and Vo− (r = 0.91, p &lt; 0.001). Highly significant correlations were present between bone formation measured by calcium kinetics (Vo+) and serum levels of bone biochemical markers (OC, r = 0.82, p = 0.001; ALP, r = 0.92, p = 0.001; and BAP, r = 0.90, p = 0.001) and between bone resorption measured by calcium kinetics (Vo−) and fasting serum levels and urine creatinine ratios of biochemical markers (TRAP, r = 0.77, p &lt; 0.001; OHP/Cr, r = 0.79, p &lt; 0.001; and NTx/Cr, r = 0.70, p &lt; 0.001). Thus, biochemical markers of bone formation and resorption can be used to predict calcium kinetic rates during skeletal growth and the early years of formation of peak bone mass, ages at which strategies to build peak bone mass are important. Biochemical markers of formation and resorption are equally useful in predicting either the bone formation rate or the resorption rate.
Plasmin-Mediated Proteolysis of Osteocalcin
Authors: Novak J. F. , Hayes J. D. , Nishimoto S. K. 
Published: April 2006

Abstract
Plasmin cleaves osteocalcin at a site within its carboxyl end, thus creating an N-midterminal 1–43 and a short C-terminal 44–49 peptides. The products of the cleavage were identified by matrix assisted laser desorption ionization time of flight mass spectrophotometry and by reversed phase high performance liquid chromatography followed by N-terminal sequence determination. When separated by sodium dodecyl sulfide-polyacrylamide gel electrophoresis in the presence of reducing agents, large (LF; N-midterminal) and a small molecular weight (SF; C-terminal) fragments can be identified. The major cleavage site involves arg43-arg44 amino acid residues, and the resulting 44–49 C-terminal fragment appears as a slow migrating band on native gels (SFnat). Elevated levels of calcium ion inhibit the plasmin-mediated lysis of osteocalcin. Plasmin-mediated cleavage of osteocalcin occurs both in solution and when bound to hydroxyapatite. Both osteocalcin cleavage products detach from the hydroxyapatite substrate. Diisopropyl fluorophosphate–inhibited plasmin does not displace osteocalcin from the hydroxyapatite surface. Previously, the C-terminal pentapeptide has been shown to be chemotactic for bone cells while bone particles lacking osteocalcin were resistant to bone resorption. We therefore hypothesize that the plasmin-mediated digestion of free and hydroxyapatite-bound osteocalcin could play a role in the regulation of bone remodeling.
Bisphosphonate Effects and the Bone Remodeling Transient
Authors: Heaney Robert P. , Yates A. John , Santora Arthur C. 
Published: April 2006

Abstract
Published randomized clinical trial data for alendronate, given at a dose of 10 mg/day, were fitted by a computer algorithm to the currently accepted model of the bone remodeling process. The purpose was to determine how much of the reported improvement in lumbar spine bone density could be attributed to the inevitable remodeling transient and how much might represent positive bone balance. Very good fits to the clinical data were easily obtained, indicating the general validity of current syntheses of bone remodeling biology. The best fit was provided by simulations produced by combinations of 36–38% suppression of remodeling activation and positive remodeling balance ranging from 1.1 to 1.4% per year. Whole body bone biomarker changes would have suggested both a slightly greater degree of suppression and a higher baseline level of remodeling than could be provided by any of the simulations if they were to fit the clinical data. Either regional skeletal heterogeneity or lack of a one-to-one quantitative relationship between remodeling changes and biomarker changes may explain the discrepancies between the two approaches.
Hydroxyapatite Induces Autolytic Degradation and Inactivation of Matrix Metalloproteinase-1 and -3
Authors: Kremer Edward A. , Chen Yan , Suzuki Ko , Nagase Hideaki , Gorski Jeffrey P. 
Published: April 2006

Abstract
In the course of studies to identify a protease capable of producing a long-lived 50 kDa fragment of bone acidic glycoprotein-75 (BAG-75), it was observed that incubation of matrix metalloproteinase (MMP)-3 (stromelysin 1) with preparations of BAG-75 led to inactivation of proteolytic function, e.g., an inability to fragment125I-labeled BAG-75 added subsequently. MMP-1 (interstitial collagenase) was also inactivated by exposure to BAG-75 preparations. Investigation of the mechanism revealed that BAG-75 preparations contained millimolar levels of inorganic phosphate which formed hydroxyapatite crystals under digestion conditions. Hydroxyapatite crystals alone and in BAG-75–hydroxyapatite complexes induced the autolytic degradation of both active and precursor forms of MMP-1 and MMP-3. Autolytic degradation in the presence of hydroxyapatite was demonstrated by a loss in catalytic function assayed with peptide and/or protein substrates, and, by fragmentation into polypeptides of &lt;10 kDa. The fate of MMP-3 incubated with hydroxyapatite depends upon the time of incubation, the free calcium concentration, and the concentration of crystals. Specifically, hydroxyapatite-induced autolysis requires a near physiological free calcium concentration of 0.5–1.0 mM. Autolysis was maximal in the presence of 150 μg/ml hydroxyapatite where MMP-3 was only partially bound to crystals. However, autolysis also occurred at higher crystal concentrations where all input MMP-3 was bound (&gt;1000 μg/ml), suggesting that autolysis may be mediated by bound enzyme. The effect of hydroxyapatite appears to be specific for MMP-1 and MMP-3 since the catalytic activity of chymotrypsin, trypsin, papain, and thermolysin remained unchanged after exposure to hydroxyapatite. These results document for the first time a novel catalytic role for hydroxyapatite crystals in vitro and provide an initial biochemical characterization of the intermolecular, autolytic, calcium ion-dependent, matrix metalloproteinase-specific degradative mechanism.
Effects of Zinc Supplementation on Vertebral and Femoral Bone Mass in Rats on Strenuous Treadmill Training Exercise
Authors: Seco C. , Revilla M. , Hernández E. R. , Gervás J. , González-Riola J. , Villa L. F. , Prof. Dr. Rico H. 
Published: April 2006

Abstract
The hypothesis that a zinc (Zn) deficit may cause osteopenia in athletes is well founded. In rats exposed to strenous exercise, we evaluated the effect of a zinc supplement on femoral and vertebral bone mass determined by dual-energy X-ray absorptiometry. Four lots of 93-day-old female Wistar rats were studied. A control group of 30 rats were not manipulated (Zn– Ex– group). The experimental group of 40 rats was fed a diet supplemented with an additional 20% of Zn/kg of feed; this group was divided into two groups of 20 rats each, one that did not exercise (Zn+ Ex–) and one that did (Zn+ Ex+). A group of 15 rats exercised but did not receive a zinc supplement (Zn– Ex+ group). Training consisted of treadmill running for 5 out of 7 days over an 11-week period. Initial speed, running time, and treadmill speed were increased gradually. Analysis of variance with the Bonferroni/Dunn test showed that the length, weight, bone mineral content (BMC), and bone mineral density (BMD) of the femur were less in the Zn– Ex+ group than in the others (p &lt; 0.008), and the weight, BMC, and BMD of the fifth lumbar vertebra also were lower in the Zn– Ex+ group than in the others (p &lt; 0.008). These findings confirm the adverse effects of strenuous exercise (treadmill running) on bone tissue in rats and the effectiveness of zinc supplementation in preventing it.
Prostaglandin E2 Induces Expression of Receptor Activator of Nuclear Factor–κB Ligand/Osteoprotegrin Ligand on Pre-B Cells: Implications for Accelerated Osteoclastogenesis in Estrogen Deficiency
Authors: Kanematsu Masahiro , Sato Takuya , Takai Hiroyuki , Watanabe Ken , Ikeda Kyoji , Yamada Yoshiji 
Published: April 2006

Abstract
Estrogen deficiency causes bone loss as a result of accelerated osteoclastic bone resorption. It also has been reported that estrogen deficiency is associated with an increase in the number of pre-B cells in mouse bone marrow. The present study was undertaken to clarify the role of altered B lymphopoiesis and of the receptor activator of nuclear factor-κB ligand (RANKL), a key molecule in osteoclastogenesis, in the bone loss associated with estrogen deficiency. In the presence of prostaglandin E2 (PGE2), the activity to form tartrate-resistant acid phosphatase (TRAP)-positive osteoclast-like cells was significantly greater in bone marrow cells derived from ovariectomized (OVX) mice than in those from sham-operated mice. Northern blot analysis revealed that PGE2 increased the amount of RANKL messenger RNA (mRNA) in bone marrow cells, not only adherent stromal cells but nonadherent hematopoietic cells; among the latter, RANKL mRNA was more abundant in OVX mice than in sham-operated mice and was localized predominantly in B220+ cells. Flow cytometry revealed that most B220+ cells in bone marrow were RANKL positive and that the percentage of RANKL-positive, B220low cells was higher in bone marrow from OVX mice than in that from sham-operated mice. The increase in the expression of RANKL and the percentage of these cells in OVX mice was abolished by the administration of indomethacin in vivo. PGE2 also markedly increased both the level of RANKL mRNA and cell surface expression of RANKL protein in the mouse pre-B cell line 70Z/3. Finally, osteoclastogenic response to PGE2 was reduced markedly by prior depletion of B220+ cells, and it was restored by adding back B220+ cells. Taken together with stimulated cyclo-oxygenase (COX)-2 activity by tumor necrosis factor α (TNF-α) and interleukin-1 (IL-1) in estrogen deficiency, these results suggest that an increase in the number of B220+ cells in bone marrow may play an important role in accelerated bone resorption in estrogen deficiency because B220+ cells exhibit RANKL on the cell surface in the presence of PGE2, thereby leading to accelerated osteoclastogenesis.
Intestinal Calcium Transporter Genes Are Upregulated by Estrogens and the Reproductive Cycle Through Vitamin D Receptor-Independent Mechanisms
Authors: Van Cromphaut SJ , Rummens K , Stockmans I , Van Herck E , Dijcks FA , Ederveen Agh , Carmeliet P , Verhaeghe J , Bouillon R , Carmeliet G 
Published: April 2006

Abstract
1α,25(OH)2-vitamin D strongly regulates the expression of the epithelial calcium channel CaT1. CaT1 expression is reduced in ERKOα mice and induced by estrogen treatment, pregnancy, or lactation in VDR WT and KO mice. Estrogens and vitamin D are thus independent potent regulators of the expression of this calcium influx mechanism, which is involved in active intestinal calcium absorption.
Introduction: Active duodenal calcium absorption consists of three major steps: calcium influx into, transfer through, and extrusion out of the enterocyte. These steps are carried out by the calcium transport protein 1 (CaT1), calbindin-D9K, and the plasma membrane calcium ATPase (PMCA1b), respectively. We investigated whether estrogens or hormonal changes during the female reproductive cycle influence the expression of these genes, and if so, whether these effects are vitamin D-vitamin D receptor (VDR) dependent.
Materials and Methods: We evaluated duodenal expression patterns in estrogen receptor (ER)α and -β knockout (KO) mice, as well as in ovariectomized, estrogen-treated, pregnant, and lactating VDR wild-type (WT) and VDR KO mice.
Results: Expression of calcium transporter genes was not altered in ERKOβ mice. CaT1 mRNA expression was reduced by 55% in ERKOα mice, while the two other calcium transporter genes were not affected. Ovariectomy caused no change in duodenal expression pattern of VDR WT and KO mice, whereas treatment with a pharmacologic dose of estrogens induced CaT1 mRNA expression in VDR WT (4-fold) and KO (8-fold) mice. Pregnancy enhanced CaT1 expression equally in VDR WT and KO mice (12-fold). Calbindin-D9K and PMCA1b expression increased to a lesser extent and solely in pregnant VDR WT animals. In lactating VDR WT and KO mice, CaT1 mRNA expression increased 13 times, which was associated with a smaller increase in calbindin-D9K protein content and PMCA1b mRNA expression.
Conclusions: Estrogens or hormonal changes during pregnancy or lactation have distinct, vitamin D-independent effects at the genomic level on active duodenal calcium absorption mechanisms, mainly through a major upregulation of the calcium influx channel CaT1. The estrogen effects seem to be mediated solely by ERα.