bluuebunny/crossref_metadata_2025_split huggingface dataset:
Binding characteristics of fluoroquinolones to synthetic levodopa melanin
Authors: Ono Chiho , Tanaka Makoto 
Published: September 2003

Abstract
To define the binding characteristics of fluoroquinolones to synthetic levodopa melanin, the binding of various drugs, including levofloxacin and ofloxacin, and positive controls (timolol and chloroquine), was investigated in-vitro. The affinity and capacity of the drug binding were calculated by Langmuir's adsorption isotherm. The affinity constant (K) and the binding capacity (rmax) of levofloxacin were similar to those of timolol and much lower than those of chloroquine. Racemic ofloxacin and its enantiomers showed similar K and rmax, suggesting that the binding lacked stereo-selectivity. The binding experiment with levofloxacin derivatives indicated that the basic nitrogen atom at position 7 of the quinolone ring, but not carboxyl group at position 3, would play a critical role in the interaction of fluoroquinolones with melanin. The melanin–drug complexes of levofloxacin and chloroquine were washed with neutral phosphate buffer, ethanol and 1 m HCl solution to explain the nature of the interaction of melanin with the drugs. Electrostatic forces mainly participate in the formation of the chloroquine–melanin complex, whereas van der Waals' and hydrophobic interactions are involved in the levofloxacin–melanin complex in addition to electrostatic forces. The interactions of various fluoroquinolones such as norfloxacin, enoxacin, sparfloxacin, ciprofloxacin and lomefloxacin with melanin were also studied. The results showed that the relative K value was: chloroquine ≅ ciprofloxacin, sparfloxacin ≥ lomefloxacin &gt; timolol, levofloxacin ≥ enoxacin, norfloxacin, and that the relative rmax value was: norfloxacin, enoxacin ≥ chloroquine, sparfloxacin &gt; levofloxacin, ciprofloxacin, timolol, lomefloxacin. The fluoroquinolones vary in their affinity and capacity to bind with melanin, and ciprofloxacin and sparfloxacin showed a stronger interaction with melanin than the other fluoroquinolones studied.
Growth factors and chemotherapeutic modulation of breast cancer cells
Authors: Ciftci Kadriye , Su Jiangfeng , Trovitch Peter B 
Published: September 2003

Abstract
A variety of molecules including growth factors are involved in the metastasis of breast cancer cells to bone. We have investigated the effects of osteoblast derived growth factors, such as insulin-like growth factor-1 (IGF-1) and transforming growth factor beta-1 (TGF-β1), on doxorubicin (adriamycin)-induced apoptosis and growth arrest of estrogen receptor positive (ER+) (MCF-7) and negative (ER–) (MDA-MB-435) breast cancer cell lines. Human breast normal epithelial (MCF-10A), breast cancer (MCF-7) and metastatic breast cancer (MDA-MB-435) cell lines were exposed to different doses of doxorubicin (0.1, 1 or 10 μm) at various exposure times (12, 24 or 48 h). The doxorubicin cytotoxicity was found to be higher in cancer cell lines (MDA-MB-435 and MCF-7) compared with normal breast epithelial cells (MCF-10A cells). Doxorubicin appeared to exert a blockade of MCF-7 and MDA-MB-435 cells at the G2/M phase, and induced apoptosis in MDA-MB-435 (29 ± 4.2% vs 3.4 ± 1.9% control) as assessed by flow cytometry, DNA fragmentation and terminal deoxynucleotidyl-transferase mediated deoxyuridine 5-triphosphate and biotin nick-end labelling (TUNEL) assays. Estradiol (E2) stimulated the growth of MCF-7 cells and increased the distribution of the cells at the G2/M and S phases. Exogenous IGF-1 partially neutralized the doxorubicin cytotoxicity in both cancer cell lines (MCF-7 and MDA-MB-435). Similarly, TGF-β1 partially neutralized the doxorubicin cytotoxicity in MDA-MB-435 cells by reducing the number of cells at the &lt;G1 phase (from 29% to 6.4%) and enhanced the doxorubicin blockade of MCF-7 (E2–) at the G0/G1 phase. Results showed that the osteoblast-derived growth factors could affect the chemotherapy response of breast cancer cells, thereby allowing for the possibility of chemotherapeutic modulation.
Effect of berberine on proliferation, cell cycle and apoptosis in HeLa and L1210 cells
Authors: Jantová Soňa , čipák L'uboš , čerňáková Marta , Košt‘álová Daniela 
Published: September 2003

Abstract
Previous studies on the anticancer activity of protoberberine alkaloids against a variety of cancer cell lines were extended to human tumour HeLa and murine leukemia L1210 cell lines. An attempt was also made to investigate the relationship between the cytotoxic activity of berberine and its molecular mechanism of action. Cytotoxicity was measured in-vitro using a primary biochemical screening according to Oyama and Eagle, and the growth inhibition assay. The in-vitro cytotoxic techniques were complemented by cell cycle analysis and determination of apoptotic DNA fragmentation in L1210 cells. Berberine acted cytotoxically on both tumour cell lines. The sensitivity of leukemia L1210 cells to the berberine was higher than that of HeLa cells. The IC100 was below 100 μg mL−1 for HeLa cells and approached a 10 μ mL−1 limit for the leukemia L1210 cells. For both cell lines the IC50 was found to be less than 4 μg mL−1, a limit put forward by the National Cancer Institute (NCI) for classification of the compound as a potential anticancer drug. In L1210 cells treated with 10–50 μ mL−1 berberine, G0/G1 cell cycle arrest was observed. Futhermore, a concentration-dependent decrease of cells in S phase and increase in G2/M phase was detected. In addition, apoptosis detected as sub-G0 cell population in cell cycle measurement was proved in 25–100 μg mL−1 berberine-treated cells by monitoring the apoptotic DNA fragmentation (DNA ladder) using agarose gel electrophoresis.
Kinetics of the Photobromination of Dichloro- and Dibromoethane. Estimate of the C–H Bond Dissociation Energies and the Heats of Formation of the CH3CCl2 and CH3CBr2 Radicals
Authors: Miyokawa Kikuo , Tschuikow-Roux Eugene 
Published: September 2003

Abstract
The kinetics of the α-H abstraction reaction RH + Br → R + HBr, RH = 1,1-dichloro (1) and 1,1-dibromoethane (2) was investigated in the temperature range 308—368 K using chloroethane and ethane as an external competitor, respectively. The relative rates were combined with the known rate parameters for chloroethane and ethane to obtain the absolute rate constants (cm3 mol−1 s−1): k1 = [6.9 ± 3.8(σ)] × 1011exp[(−7300 ± 360 cal mol−1)/RT] and k2 = [2.2 ± 1.2(σ)] × 1011exp[(−7110 ± 360 cal mol−1)/RT]. Using a justifiable approximation concerning the magnitude of the activation energies for the reverse reaction, the following thermochemical quantities (kcal mol−1) were derived: ΔH°f(CH3CCl2) = 11.9 ± 1.2, D°(CH3CCl2-H) = 95.1 ± 1.2, ΔH°f(CH3CBr2) = 33.5 ± 1.3, D°(CH3CBr2-H) = 94.9 ± 1.2. The relation between the reaction thermochemistry and the reactivity in chlorination and bromination of haloethanes is discussed.
Behavior of Biradicals Generated from a Norrish Type-I Reaction of 2,2-Diphenylcycloalkanones. Chain-Length Dependence and Magnetic Field Effects
Authors: Suzuki Itsuko , Tanaka Ryoko , Yamaguchi Akinori , Maki Shin-ichiro , Misawa Hiroaki , Tokumaru Katsumi , Nakagaki Ryoichi , Sakuragi Hirochika 
Published: September 2003

Abstract
The reaction course of acyl-diphenylmethyl biradicals (α-oxo-ω,ω-diphenyl-α,ω-alkanediyl biradicals), O=C↑–(CH2)n−2–C↑Ph2 (3BR-n), generated from the Norrish type-I reaction of 2,2-diphenylcycloalkanones (CK-n) with various ring sizes in methanol, is switched from intramolecular disproportionation (n = 6, 7), giving a diphenylalkenal, to acyl-phenyl recombination (n ≥ 9), affording a cyclophane derivative. The behavior of 3BR-9 derived from CK-9 was studied in detail; the photolysis of CK-9 afforded an open-chain and a cyclic decarbonylation product together with an unsaturated aldehyde and a 4-methylene-2,5-cyclohexadienyl ketone (a pre-cyclophane). The photolysis of this ketone gave the same products that arose from the photolysis of CK-9, presenting the possibility that the decarbonylation products and a part of the aldehyde are formed as secondary products during irradiation.
The magnetic field dependence of the lifetimes of 3BR-n (n = 12 and 13) generated from CK-12 and 13, respectively, was measured in methanol by means of a pulsed-laser excitation technique. The rate constants for intersystem crossing showed a maximum at a relatively low field strength, which decreased with increasing the field strength to level off to an asymptotic value at &gt; 1.5 kG. The results show that the role of hyperfine coupling in intersystem crossing is less important in these systems, presumably because of the presence of a carbonyl oxygen and the absence of a hydrogen atom at the radical center.
Oxidative Iodination of Arenes with Manganese(IV) Oxide or Potassium Permanganate as the Oxidants
Authors: Lulinski Piotr , Skulski Lech 
Published: September 2003

Abstract
Novel and easy laboratory methods (novel Procedures 1—4) are presented for the oxidative mono- and diiodination of both activated and deactivated arenes, which gave the pure iodinated products in 62—89% yields. The reactions were carried out in the anhydrous, strongly acidic system, I2/activated MnO2/AcOH/Ac2O/concd H2SO4, firstly at r.t. for 2 h, then at 45—55 °C for 2—9 h. The resulting mixtures were poured into excess aq Na2SO3 solution buffered with (NH4)2CO3 to neutralize H2SO4. The following workups are given. Similarly, on carrying out the iodination reactions (at 35 °C, for one hour) in the anhydrous, strongly acidic system, I2/KMnO4/AcOH/Ac2O/concd H2SO4, it was possible to mono- or diiodinate several deactivated arenes in 73—87% yields (improved Procedures 5 and 6).
Properties and Application Feasibility of an Osmium-Oxygen Thin Film Prepared by DC-Glow-Discharge Deposition from Osmium Tetraoxide
Authors: Inoue Hitoshi , Satoh Kazuyuki 
Published: September 2003

Abstract
An osmium-oxygen thin film was prepared by d.c.-glow-discharge deposition from osmium tetraoxide with a filming rate of 1 nm s−1. The fundamental properties of the films were investigated. The prepared films had a homogeneous amorphous structure and 10−4 Ω cm order of resistivity. Since the transparency of a 20 nm thick film was about 80% for visible light, a transparent conductive film could be obtained on glass or plastic substrates. X-Ray photoelectron spectroscopy measurements showed that the film contained 30 at.% of osmium and 70 at.% of oxygen, which might make the film be easily etched by an oxygen-plasma, or be electrically oxidized. Since the osmium film could be patterned by oxygen-plasma etching or by a lift-off method, which are familiar lithography techniques in the field of semiconductor devices, it is expected to be used as micro-electrode or micro-wiring materials. Low-temperature film preparation also makes it possible to be applied as an X-ray mask material for X-ray lithography.
Second-Order Optical Nonlinearity of In Situ Prepared Polyurethanes Having Thiazolylazo Chromophores
Authors: Matsui Masaki , Kushida Mitsugu , Funabiki Kazumasa , Muramatsu Hiroshige , Shibata Katsuyoshi , Hirota Kazuo , Hosoda Masahiro , Tai Kazuo 
Published: September 2003

Abstract
The in situ prepared polyurethane films of the thiazolylazo NLOphores showed d33values of 38—49 pm V−1. The temporal stability of the poled NLOphore was in the following order of the polymers: network &gt; side chain &gt; main chain.
Characteristic Monomial Tables for Enumeration of Achiral and Chiral Isomers
Authors: Fujita Shinsaku 
Published: September 2003

Abstract
The characteristic monomial table of an achiral group is applied to combinatorial enumeration of the following types: (1) achiral isomers and enantiomeric pairs, (2) achiral isomers and chiral isomers, (3) enantiomeric pairs, and (4) achiral isomers. The cycle index of each case is obtained by using the same set of subduced cycle indices derived from characteristic monomials, where the coefficients of the subduced cycle indices are given in advance.
Identification of Active Crystalline Phase in La-K-Cu-V Mixed Oxide for the Simultaneous Removal of Nitrogen Oxides and Diesel Soot
Authors: Teraoka Yasutake , Shangguan Wengfeng , Jansson Kjell , Nygren Mats , Kagawa Shuichi 
Published: September 2003

Abstract
The oxide catalyst having an overall metal composition of La/K/Cu/V = 9/1/7/3 (denoted as LKCVO) showed an excellent selectivity to NOx reduction into N2 in the simultaneous NOx-soot removal reaction, though it was a mixture of several crystalline phases. In order to identify the real active phase, LKCVO was characterized by X-ray diffraction (XRD) and by elemental analysis of individual grains in a transmission electron microscope (TEM) equipped with an energy dispersive spectrometer (EDS). LKCVO was found to be composed of CuO and mixed metal oxides analogous to La2CuO4, LaVO4, and La3VO7. By comparing the catalytic activity of LKCVO with those of single-phase oxides synthesized according to the results of XRD and TEM/EDS, (La2−xKx)(Cu0.95V0.05)O4 with 0.05 ≤ x ≤ 0.1 was identified to be the real active phase in LKCVO for the simultaneous NOx-soot removal reaction.
Syntheses, Characterizations, and Redox Behavior of Optically Active Viologens and Bisviologens
Authors: Tsukahara Keiichi , Kaneko Junko , Miyaji Tomoko , Abe Kaya , Matsuoka Maki , Hara Tomoko , Tanase Tomoaki , Yano Shigenobu 
Published: September 2003

Abstract
Optically active viologens, containing [1-(1-naphthyl)-, 1-phenyl-, and 1-cyclohexylethyl]carbamoylmethyl groups, have been synthesized and characterized. The redox behavior of the chiral viologens was studied compared with achiral viologens. The monoviologens containing naphthyl groups show an intermolecular charge-transfer interaction between the bipyridinium and naphthyl groups in aqueous solution. The association constants are dependent on the chirality of the viologens and larger in the (S,S)- and (R,R)-isomers than in the (R,S)-one. Chiral bisviologens, in which two viologen units are linked with a trimethylene chain, have also been synthesized and characterized. Although the intermolecular charge-transfer interaction between the bipyridinium and viologen units of bisviologens was very weak in solution, such an interaction was appreciably observed in a solid state, which was confirmed by X-ray crystallography. Monoradical trications produced by a one-electron reduction of bisviologens disproportionate more easily in the (R,S)-isomers than in the (S,S)- and (R,R)-ones. The disproportionation is controlled by the steric bulk of the chiral substituents in intramolecular association between two viologen radical units of diradical dications.
Unusual Electrical Properties of Neutral Mixed-Stack Charge-Transfer Complexes of DAP–BRL (DAP = 1,6-Diaminopyrene, BRL = p-Bromanil)
Authors: Fujinawa Tasuku , Goto Hirotoshi , Naito Toshio , Inabe Tamotsu , Akutagawa Tomoyuki , Nakamura Takayoshi 
Published: September 2003

Abstract
Two polymorphs of 1 : 1 charge-transfer complexes of DAP–BRL were grown from a benzene solution. The γ-form is triclinic, space group P1-, a = 16.53(1), b = 17.80(1), c = 8.235(5) Å, α = 96.42(7), β = 97.76(6), γ = 120.79(5)°, V = 2015(3) Å3, and Z = 4; the δ-form is monoclinic, space group Pn, a = 6.862(3), b = 9.891(2), c = 15.246(2) Å, β = 101.78(2)°, V = 1012.9(5) Å3, and Z = 2. Both crystals comprise mixed stacks of donors and acceptors. The molecular geometry, the CO stretching frequencies, and the EPR spectra indicate that most of the component molecules in both crystals are in the neutral state. The electrical conductivity is, however, found to be high; especially the value for γ-DAP–BRL (10−1Ω−1 cm−1) is unusually high as a neutral mixed-stack complex.
A Pulse-Product-Yield-Detected ESR Study on the Photolysis of Nitronaphthalene–Aniline Bifunctional Chain Molecule
Authors: Konishi Yoshinari , Maruthamuthu Pichai , Okazaki Masaharu , Arakawa Youko , Nakagaki Ryoichi 
Published: September 2003

Abstract
The effects of microwaves (MW) on the photolysis of a benzene solution of N-[12-(4-nitro-1-naphthyloxy)dodecyl]aniline under a magnetic field were investigated. The reaction intermediate was identified as a biradical the ESR spectrum of which was recorded by plotting the MW effect as a function of the magnetic field under which the reaction proceeds. The kinetic parameters of the reaction system were estimated from the MW effects observed as functions of the delay period from the laser pulse for putting on/off the MW pulse.
Formation of a Trinuclear Mercury(II) Complex Mediated by a Phosphorane: Molecular Structure of [Hg{Hg(I)(Ph3PCHCOPh)(μ-I)2}2]
Authors: Kalyanasundari Balasubramanian , Panchanatheswaran Krishnaswamy , Parthasarathi Viraraghavan , Robinson Ward T 
Published: September 2003

Abstract
Phenacylidenetriphenylphosphorane reacts with HgI2 in 2 : 3 molar ratio to form a novel trinuclear iodobridged symmetrical complex whose structure has been elucidated by IR, multinuclear NMR, and X-ray crystallography. The Hg···Hg distance [3.648(1) Å] indicates a negligible bonding interaction between the mercury atoms.
Colloidal Titration of Chitosan and Critical Unit of Chitosan to the Potentiometric Colloidal Titration with Poly(vinyl sulfate) Using Toluidine Blue as Indicator
Authors: Hattori Toshiaki , Katai Kazuhito , Kato Masanao , Izume Masato , Mizuta Youichi 
Published: September 2003

Abstract
Three sorts of characterized chitosan were measured by visual titration and potentiometric titration with poly(vinyl sulfate) using Toluidine Blue as the indicator, to evaluate the stoichiometry and the accuracy. The measurement values for two dialyzed chitosans by both colloidal titration methods agreed with the values obtained by the acid-base titration. The relative differences between the acid-base titration and the colloidal titration were &lt; 2%, and the relative standard deviation of the potentiometric colloidal titration was &lt; 1%. For a oligo-chitosan (ChO) which consisted of several d-glucosamine oligosaccharides, the value obtained by the potentiometric colloidal titration was much smaller than the value from the acid-base titration. The inadequate result was due to the low stability constant of ChO–PVS. The observed values in the colloidal titration of ChO were evaluated for the content of each d-glucosamine oligosaccharide, and a critical unit that indicated the least unit of d-glucosamine oligosaccharide that contributed to the measurement value was estimated. The critical unit was four, tetra(d-glucosamine saccharide).
Determination of Trace Molybdenum in Water Samples by Electrothermal Atomic Absorption Spectrometry after Preconcentration with Miniaturized Coprecipitation
Authors: Shimizu Tokuo , Ito Hirobumi , Kawaguchi Hiroshi , Shijo Yoshio 
Published: September 2003

Abstract
Miniaturized coprecipitation with hydrous manganese(IV) oxide was studied for the preconcentration of sub μg dm−3 levels of molybdenum in water samples. Manganese(IV) oxide was produced by a reaction of permanganate ion with ethanol in the presence of 0.1 mol dm−3 hydrochloric acid. A nanogram amount of molybdenum in a 10 cm3 sample was quantitatively coprecipitated. The amount of manganese required was 0.1—0.40 mg for a 10 cm3 sample. The precipitate was collected on a 10 μm membrane filter, and then dissolved in 50 mm3 of 5.6 mol dm−3 nitric acid and 75 mm3 of 1% hydrogen peroxide. An 80-fold preconcentration factor was obtained by this procedure. The molybdenum concentration was determined by electrothermal atomic absorption spectrometry using a pyrolytic graphite coated cuvette. The detection limit (3σ) was found to be 8.9 ng dm−3. The proposed method was successfully applied to river water and snow samples.
Correlation of Exciplex Formation with Ground State Conformations in Flexible Bichromophoric Esters: 2-(1-Pyrenyl)ethyl p-Cyanobenzoate and Its Model Compounds
Authors: Kawakami Jun , Furuta Toshiaki , Nakamura Junko , Uchida Akira , Iwamura Michiko 
Published: September 2003

Abstract
Two kinds of model compounds for a bichromophoric ester, 2-(1-pyrenyl)ethyl p-cyanobenzoate (P2CN), were synthesized: 1-substituted 2-(1-pyrenyl)ethyl p-cyanobenzoates (RP2CN, R = Me, Et, and Ph) as flexible model compounds and trans-2-(1-pyrenyl)cyclohexyl p-cyanobenzoate (cyclo-P2CN) as a rigid model compound. P2CN and all the model compounds had an intramolecular exciplex emission (φEX ≈ 0.010) and efficient quenching of fluorescence from the locally excited pyrene part (φLE ≈ 0.001). The decay lifetimes of the locally excited pyrene were 365 ps for P2CN and 66 ps for cyclo-P2CN, which were respectively identical with the risetime for the exciplex formation. The 1H NMR of both P2CN and RP2CN showed the shifts of H2″ and H3″ of the p-cyanobenzoyl to the higher and H10′ of 1-pyrenyl signals to the lower magnetic field compared with those of the reference compounds, approaching towards those of cyclo-P2CN. NOE was observed between H10′ and H2″ of cyclo-P2CN, and, although very weak, between H2′ and H3″ of MeP2CN. In the solid state, P2CN adopts a folded conformation, which is roughly close to the gauche conformation, with the dihedral angle of 57.5° between p-cyanophenyl ring and pyrenyl ring based on X-ray crystallographic analysis on a leaflet monoclinic crystal, suggesting the exciplex formation from this conformation in P2CN.
Effects of N-Terminal l-Amino Acid Residues on Helical Screw Sense in Achiral Peptides
Authors: Inai Yoshihito , Kurokawa Yuji , Ida Atushi , Hirabayashi Tadamichi 
Published: September 2003

Abstract
To understand the effects of N-terminal l-residues on dominating helical screw sense in achiral peptides, we adopted six kinds of peptides Boc–X–(Aib–ΔPhe)2–Aib–OMe (Boc, t-butoxycarbonyl; OMe, methoxy), in which the X residue is an l-amino acid of alanine (Ala), leucine (Leu), valine (Val), phenylalanine (Phe), 1-naphthylalanine (Nap), or proline (Pro). The segment –(Aib–ΔPhe)2– was used for a backbone composed of two “enantiomeric” (left-/right-handed) helices. Actually, this could be confirmed by 1H NMR and CD spectroscopy on Boc–(Aib–ΔPhe)2–Aib–OMe, which took left- and right-handed 310-helices with the same content. All peptides were also found to take 310-type helical conformations in CDCl3 from solvent accessibility of NH resonances. Chloroform, acetonitrile, methanol, and tetrahydrofuran were used for solvents in CD measurement. All peptides in all solvents showed marked exciton couplets around 280 nm with a positive peak at longer wavelengths. Consequently, when an N-terminal l-residue, irrespective of types of l-residues, is introduced into a helical segment of achiral peptide, its main chain prefers the left-handed screw sense. The peptide with X = Alashowed the smallest amplitude of exciton couplets in each solvent, meaning that the Ala residue with the smallest side chain (methyl group) had the least effective chirality for taking a one-side helical screw sense preferentially, compared with the other residues used here.