bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vascular viewpoint
Authors: Lindsay TF , Dueck AD 
Published: June 2006

Question: Is duplex scanning superior to clinical vein graft surveillance with respect to amputation rates, quality of life, and cost following femoropopliteal or femorocrural vein bypass graft? Population: Between 1998 and 2001, patients from 29 centers in the UK and Europe who had a patent vein graft 30 days following femoropopliteal or femorocrural vein bypass surgery for critical ischemia, claudication or symptomatic popliteal aneurysms were recruited for the study. Methods and results: There were 592 patients included in this multicenter randomized controlled trial. Patients with patent vein grafts at 30 days were randomized to receive or not receive duplex surveillance in addition to clinical examinations and ankle-brachial indices at 6 weeks (time of recruitment), and 3, 6, 9, 12 and 18 months. Stenoses within grafts were defined as slow peak systolic velocity (<45 cm/s), or a ratio of peak systolic velocity in an area of stenosis to any other area within 2 cm of >2. The primary endpoints were time to amputation and time to vascular mortality (MI, CHF, arrhythmia or CVA). Secondary outcomes included graft patency (whether primary or secondary, assisted or unassisted), cost, and quality of life as measured by SF-36 and EuroQol. The primary endpoints were analyzed according to an intention-to-treat analysis using Cox-regression and Kaplan-Meier life tables, while secondary outcomes were analyzed by the Mann-Whitney test and a t-test. Approximately 11% of patients died during the study, while 12% withdrew (45% of which were due to amputations). There were significantly more diagnostic interventions in the clinical follow-up group (31% vs 22%, P = 0.01). Between the clinical follow-up and duplex groups, there was no difference in amputation rate (7% vs 7%) or vascular death rate (3% vs 4%). A greater proportion of patients in the clinical follow-up group had a stenosis in the graft identified at the end of the study (19% vs 12%, p = 0.04). There were no differences in Kaplan-Meier estimates of primary, primary assisted and secondary patency rates between the two groups at 18 months. No differences in quality of life as measured by SF-36 or EuroQol were detected between the two groups. The cost per patient was greater in the duplex group (US$ 1537 vs US$ 2406, p = 0.002). Conclusion: The authors conclude that surveillance with duplex scanning following femoropopliteal or femorocrural bypass was more costly, but did not result in lower amputation rates.
Changes in Serum Insulin-Like Factor 3 during Normal Male Puberty
Authors: Ferlin Alberto , Garolla Andrea , Rigon Franco , Rasi Caldogno Lucia , Lenzi Andrea , Foresta Carlo 
Published: June 2006

Abstract
Context: Insulin-like factor 3 (INSL3) is produced by the Leydig cells, and in adults, its secretion is dependent on the state of differentiation of these cells, which, in turn, is dependent on LH. However, the secretion and regulation of INSL3 during puberty is unknown.
Objective: Our objective was to evaluate INSL3 concentrations during normal male puberty and the relation of INSL3 to LH, FSH, and testosterone.
Design and Setting: We conducted a cross-sectional study from January to December 2005 at academic clinics.
Patients: Participating in the study were 75 healthy male subjects aged 9.5–17.5 yr, homogeneously distributed into five pubertal groups of 15 according to Tanner stages.
Main Outcome Measures: We assessed mean testicular volume and LH, FSH, testosterone, and INSL3 concentrations in relation to age and pubertal stage.
Results: We observed an increase of INSL3 and LH levels from Tanner stage 2 to 4, and an increase of FSH from stage 2 to 3. Testosterone levels increased from stage 3 to 4. No differences were seen for all measured hormones between stages 4 and 5. The increase in INSL3 seemed therefore to anticipate the increase in testosterone. However, INSL3 plasma concentrations at pubertal stages 4 and 5 are about one fourth of adult levels, whereas FSH, LH, and testosterone reached adult levels by stage 4. Positive significant correlations were found between INSL3 and LH for all pubertal stages.
Conclusions: This study provides information on the physiological dynamics of INSL3, showing that the serum concentrations of this hormone increased progressively throughout puberty under the differentiating action of LH on Leydig cells. INSL3 is therefore confirmed to represent a marker of Leydig cell differentiation and function. However, a prolonged exposure to LH seems to be necessary to reach INSL3 concentrations of adults. A possible use of INSL3 in puberty disorders is promising.
Estradiol Potentiates Ghrelin-Stimulated Pulsatile Growth Hormone Secretion in Postmenopausal Women
Authors: Veldhuis Johannes D. , Keenan Daniel M. , Iranmanesh Ali , Mielke Kristi , Miles John M. , Bowers Cyril Y. 
Published: June 2006

Abstract
Context: Ghrelin and an estrogen-rich milieu individually amplify pulsatile GH secretion by increasing the amount of hormone released per burst. However, how these distinct agonists interact in controlling pulsatile GH output is not known.
Objective: The objective of the study was to test the hypothesis that elevated estradiol (E2) concentrations potentiate hypothalamo-pituitary responses to a near-physiological ghrelin stimulus.
Design: This was a double-blind, placebo-controlled, prospectively randomized, parallel-cohort study.
Setting: The study was conducted at an academic medical center.
Subjects: Twenty-one postmenopausal women participated in the study.
Interventions: Eleven subjects received placebo (Pl) and 10 others E2 transdermally in escalating doses over 3 wk to mimic late follicular-phase E2 concentrations. Saline or a submaximally stimulatory amount of ghrelin (0.3 μg/kg) was infused iv on separate randomly ordered mornings fasting after 17–21 d of Pl or E2 administration.
Outcomes: Outcomes included serum concentrations of E2, ghrelin, GH, IGF-I, IGF binding protein (IGFBP)-1 and IGFBP-3, and the estimated mass and waveform of stimulated GH secretory bursts.
Results: Administration of E2 yielded late follicular-phase E2 concentrations. Compared with Pl, E2 did not alter ghrelin concentrations but reduced IGF-I and IGFBP-3 and elevated IGFBP-1 concentrations. Compared with saline, ghrelin infusion amplified pulsatile GH secretion by 7.1-fold (P &lt; 0.01). The effect of E2 alone was 2.0-fold placebo and that of combined ghrelin/E2 10.4-fold (P &lt; 0.01). Ghrelin and E2 accelerated initial GH release individually but nonadditively by more than 2-fold (P &lt; 0.01).
Conclusions: Estrogen augments ghrelin’s near-physiological stimulation of pulsatile GH secretion and mimics ghrelin’s acceleration of initial GH release. Thus, we hypothesize that estrogen and a GH secretagogue act via independent as well as convergent mechanisms.
Fluorescence Quenching of Fluorenone by Alcohols
Authors: Fujii Tsuneo , Sano Masayuki , Mishima Shozi , Hiratsuka Hiroshi 
Published: June 2006

Abstract
The absorption and fluorescence spectra of fluorenone have been observed in various solvents. The fluorescence intensity increases with increasing solvent polarity, except in alcoholic solvents. The relative fluorescence intensity of fluorenone in acetonitrile is about 14-times greater than that in methanol. There are isosbestic points in the absorption spectra of fluorenone in mixed solvents comprising ethanol–cyclohexane and ethanol–acetonitrile, indicating the formation of a 1 : 1 hydrogen-bonded complex between fluorenone and ethanol. The equilibrium constants for the complex formation are estimated to be 2.0 ± 0.5 and 0.6 ± 0.2 mol−1 dm3 in ethanol–cyclohexane and ethanol–acetonitrile solvents, respectively. The results indicate that the complex formation changes the relative energy of the singlet and triplet states, which have n–π* and π–π* characters, respectively. The complex formation causes a strong fluorescence quenching of fluorenone in the alcohols. A plot of the fluorescence quenching also shows that there is a route for excited-state quenching. It is concluded that the S1 state has mainly an n–π* character in both nonpolar and alcoholic solvents, while a π–π* character in the S1 state increases in polar and non-hydrogen bonding solvents. CNDO/S calculations support the experimental results.
Ultrasonic Relaxations in Aqueous Solutions of Piperidine and Pyrrolidine
Authors: Nishikawa Sadakatsu , Gouhara Rumi 
Published: June 2006

Abstract
In order to examine ultrasonic absorption mechanisms and dynamical properties in aqueous solutions of heterocyclic amines, the absorption coefficients in a frequency range from 3.0 to 220 MHz were measured in solutions of pyrrolidine and piperidine at 25 °C. In the solution of pyrrolidine, a single relaxational absorption associated with a proton transfer reaction was observed, and the rate and thermodynamic parameters were determined from the concentration dependence of the relaxation frequency and the maximum absorption per wavelength. In the solution of piperidine, another relaxational absorption in addition to that due to the proton transfer reaction was observed in the relatively concentrated solution. It was attributed to a perturbation of an equilibrium associated with an aggregation reaction of nonionized molecules. The mean aggregation number and the rate parameters were estimated from the solute concentration dependence of the relaxation parameters. The results were compared with those observed in aliphatic amine solutions.
β-Molecular Rearrangement Process, But Not an α-Process, as Governing the Homogeneous Crystal-Nucleation Rate in a Supercooled Liquid
Authors: Hikima Takaaki , Hanaya Minoru , Oguni Masaharu 
Published: June 2006

Abstract
The time dependence of the growth rate of homogeneous-nucleation-based (HNB) crystallization in o-terphenyl was tracked by a temperature-jump method through microscopic observations, and HNB crystallization was found to proceed at a steady rate, specified by the tracking temperature just after the jump. Two sets of numerical computations were carried out according to a classical homogeneous nucleation theory for the temperature-jump experiment on alternative assumptions that the homogeneous nucleation process is governed by the α-molecular rearrangement process or by the β-process in the liquid. From a comparison between the experimental and calculated results, the homogeneous nucleation, and thus the crystal growth as well, were concluded to be governed by the β-rearrangement process rather than the α-process, differently from the common recognition that they are governed by the latter.
One-Electron Reductive Cleavage of the C–Cl Bond of ArCF2Cl: Convenient Route for the Synthesis of ArCF2 Derivatives
Authors: Yoshida Masato , Morishima Ayako , Suzuki Daiki , Iyoda Masahiko , Aoki Kozo , Ikuta Shigeru 
Published: June 2006

Abstract
When ArCF2Cl was reacted with PhSeNa in DMF in the presence of light, it was found that a SRN1 type reaction occurred to give ArCF2SePh. As the reaction did not proceed without light, the substitution reaction should be initiated by photo-induced electron transfer from PhSe− to ArCF2Cl. The cleavage of the C–Cl bond of PhCF2Cl by one-electron reduction with samarium(II) iodide to give a PhCF2 radical and chloride ion was also observed. The PhCF2 radical, thus formed, was trapped by styrene and phenylacetylene before it was reduced to PhCF2 anion. UHF/3-21G calculation demonstrated that one-electron reduction in PhCF2Cl led the spontaneous dissociation of the C–Cl bond to the PhCF2 radical and Cl−, but the PhCF3 radical anion existed as a stable form.
Solution Studies of Sulfur-Stabilized Lithiated Allylic Carbanions: HOESY (6Li–1H) NMR Spectroscopy of Lithiated (E)-1-(t-Butylthio)but-2-ene and (E)-1-(Phenylthio)but-2-ene
Authors: Glendenning Lionel , Bampos Nick , Field Leslie D 
Published: June 2006

Abstract
The nature of the lithium counter cations association with sulfur-stabilized allylic carbanions is investigated by 2-D HOESY (6Li–1H) spectroscopy. The association is best described as either an unsymmetrical dihapto(η2)-bonded lithium to the C1 and C2 carbons or a monohapto(η1)-bonded lithium to C1 in a position close to C2. The lithium is spatially closer to C1 than C2 and there is no indication of interaction with the C3 carbon. These structural traits for lithiated (E)-1-(t-butylthio)but-2-ene in THF and in the presence of TMEDA at 220 K differ markedly to those obtained from the low temperature X-ray crystal structure of this anionic system.
Copper-Promoted Reaction of Aryl Iodides with Activated Methine Compounds
Authors: Pivsa-Art Sommai , Fukui Yuka , Miura Masahiro , Nomura Masakatsu 
Published: June 2006

Abstract
The reaction of aryl iodides with an activated methine compound, diethyl acetamidomalonate, can efficiently proceed in the presence of CuI and NaH in DMSO to give diethyl acetamido(aryl)malonates, which may be useful precursors for α-arylglycines, in good yields. Although the reaction with another methine substrate, ethyl 2-cyanopropionate, also affords the expected coupling products, no substitution products are obtained in the case of diethyl methylmalonate, arenes together with an oxidative coupling compound of the ester being formed.
α-Sulfenyl-Directed Ring-Opening Reactions of Epoxides. 1. Highly Regio- and Stereoselective Reaction with Organo-Aluminum Reagents and Application to the Synthesis of an Aggregation Pheromone
Authors: Liu Changqing , Hashimoto Yukihiko , Kudo Kazuaki , Saigo Kazuhiko 
Published: June 2006

Abstract
The reaction of 1-phenylthio-2,3-epoxyalkanes with trialkylaluminum showed definite C-2 selectivity for nucleophilic ring-opening and gave C-2 alkylated products exclusively with the complete retention of the configuration at the C-2. In contrast, upon reacting with alkenyl(dialkyl)aluminum, dialkyl(alkynyl)aluminum, or DIBAL, the nucleophilic attack occurred at the C-1 with concomitant rearrangement of the sulfenyl group to the C-2 with the complete inversion of the configuration at the C-2. The reactions of these epoxides were considered to proceed via an episulfonium ion intermediate. Upon applying the present reaction, an aggregation pheromone of African Palm Weevil was stereoselectively synthesized in short steps.
Deactivation of Cd(53PJ) by H2 and D2: Branching Ratios for the Production of CdH and CdD
Authors: Umemoto Hironobu , Ohsako Nobuhiro 
Published: June 2006

Abstract
The deactivation processes of Cd(53P1) and Cd(53P0) by H2 and D2 were examined by employing a laser excitation-depletion technique. The concentration of the ground-state Cd(51S0) atoms was measured in both the presence and absence of an intense saturable pump laser beam. In the presence of a pump laser, the concentration decreased in accordance with the production of CdH(CdD). From this decrease, the branching ratios for the production of CdH(CdD) could be determined. The depletion was unaffected when N2 was added. This suggests that the branching ratios are the same for Cd(53P1) and Cd(53P0), although the production of CdH(CdD) is endothermic for Cd(53P0). The branching ratios were 0.81 ± 0.04 for H2 and 0.76 ± 0.06 for D2. The efficient production of CdH(CdD) from not only Cd(53P1), but also Cd(53P0), can be accounted for by correlational considerations.
Simple Synthesis of trans-α,β-Dibenzyl-γ-butyrolactone Lignans by Diastereoselective Reduction of α-Benzylidene-β-benzyl-γ-butyrolactones Using NaBH4–NiCl2
Authors: Moritani Yasunori , Fukushima Chiaki , Miyagishima Toshikazu , Ohmizu Hiroshi , Iwasaki Tameo 
Published: June 2006

Abstract
trans-α,β-Dibenzyl-γ-butyrolactone lignans were synthesized by stereoselective reduction of α-benzylidene-β-benzyl-γ-butyrolactones using NaBH4–NiCl2. The reduction is found to proceed via conjugate addition of a hydride to an α-benzylidene-β-benzyl-γ-butyrolactone and the stereoselective protonation of the resulting metal enolate. The stereoselectivity would be brought about by the conformational rigidity of the phenyl moiety of the α-benzyl group induced by 1,3-allylic strain.
N,N′-Difluoro-1,4-diazoniabicyclo[2.2.2]octane Salts, Highly Reactive and Easy-to-Handle Electrophilic Fluorinating Agents
Authors: Umemoto Teruo , Nagayoshi Masayuki 
Published: June 2006

Abstract
A series of N,N′-difluoro-1,4-diazoniabicyclo[2.2.2]octane salts were synthesized in a pure form by the fluorination of 1,4-diazabicyclo[2.2.2]octane with F2 diluted with N2 in the presence of a Brønsted acid in fluoro alcohol or acetonitrile or by fluorination followed by a treatment with a different Brønsted or Lewis acid. Their complete structural assignment was made based on spectral and elemental analyses of the isolated crystals. A great through-bond interaction between the two N–F’s of the salt was observed on 19F NMR. An assessment was made of the usefulness of N,N′-difluoro-1,4-diazoniabicyclo[2.2.2]octane bis(triflate), bis(HSO4), bis(BF4), and bis(SbF6) salts for electrophilic fluorination; the bis(BF4) salt was demonstrated to be widely applicable as a highly reactive and easy-to-handle fluorinating agent. Thus, the bis(BF4) salt readily fluorinated activated aromatics, active methylene compounds or their salts, substituted styrenes, and vinyl acetates under mild conditions. It was shown that one N–F of the salt was effective for fluorination and that the other N–F played a role to activate fluorination through the bonds. Thus, the reaction mechanism was discussed, and fluorination followed by an immediate intramolecular one-electron transfer was suggested.
Palladium(II)-Catalyzed Conjugate Addition of Aromatics to α,β-Unsaturated Ketones and Aldehydes with Arylantimony Compounds
Authors: Cho Chan Sik , Motofusa Shin-ichi , Ohe Kouichi , Uemura Sakae 
Published: June 2006

Abstract
Triarylstibines react with α,β-unsaturated ketones and aldehydes in acetic acid at room temperature in the presence of AgOAc and a catalytic amount of Pd(OAc)2 to afford the conjugate addition products (the formal hydroarylated compounds to an olefinic part) in good yields. In contrast, diarylantimony chlorides, arylantimony dichlorides, and diphenylantimony acetate react with the enones and enals even in the absence of AgOAc to afford the same products in higher yields compared with those from triarylstibines. These are new C–C bond-forming reactions using arylantimony(III) compounds in which the formation of a palladium enolate or a trivalent antimony enolate is proposed as an intermediate.
Crystalline-State Reaction of Cobaloxime Complexes. 19. A New Mode of Racemization of the 1-Cyanoethyl Group
Authors: Ohgo Yoshiki , Ohashi Yuji 
Published: June 2006

Abstract
The crystal of [(R)-1-cyanoethyl][bis(dimethylglyoximato)](3-hydroxypyridine)cobalt(III) benzene solvate showed racemization along with a retention of the single-crystal form upon exposure to a fluorescent lamp. The crystal data before irradiation are as follows: [Co(C3H4N)(C4H7N2O2)2(C5H5NO)] ·2C6H6, F.W. = 594.6, triclinic, P1, Z = 2, a = 11.646(3), b = 13.267(4), c = 11.303(3) Å, α = 102.57(2), β = 101.27(2), γ = 113.38(2)°, V = 1485.2(9) Å3, Dx = 1.33 Mg m−3, μ(Mo Kα) = 0.624 mm−1, F(000) = 624, and T = 296 K. The structure was solved by the direct method and refined to R = 0.067, wR2 = 0.180. Upon exposure to a fluorescent lamp, the cell dimensions were gradually changed, and became significantly small after 150 h of irradiation. The cell dimensions became as follows: a = 11.596(4), b = 13.287(3), c = 11.297(2) Å, α = 102.51(2), β = 101.26(2), γ = 113.37(2)°, and V = 1481.1(8) Å3. The analysed structure showed that a crystallographic inversion center appeared between the two molecules, and that the space group changed from P1 to . The 1-cyanoethyl groups of the two molecules were transformed to disordered racemates. In the process of racemization, the cyano and methyl groups were exchanged, although the methyl group has been exchanged with hydrogen in the related crystals so far observed. The racemic crystal obtained from a solution showed approximately the same structure as that by photoirradiation. The reason why such a new mode of racemization occurred was clearly explained by the size and shape of the reaction cavities for the two 1-cyanoethyl groups in the structure before irradiation.
Rotational Isomers and Molecular Structures of (E)-Propionaldehyde Oxime as Studied from Electron Diffraction and Microwave Spectroscopic Data
Authors: Iijima Kinya , Matsuoka Mayumi , Sakaizumi Takeshi , Ohashi Osamu 
Published: June 2006

Abstract
The molecular structures of two rotational isomers (anticlinal and synperiplanar forms) of gaseous (E)-propionaldehyde oxime have been determined from electron diffraction and microwave spectroscopic data. The anticlinal form is more stable by 0.15 ± 0.10 kcal mol−1 than the synperiplanar form. The molecular parameters of the anticlinal form are rg(C1–C2) = 1.552(3) Å, rg(C2–C3) = 1.493(2) Å, rg(C3=N) = 1.284(2) Å, rg(N–O) = 1.429(2) Å, ∠C1C2C3 = 111.5(1)°, ∠C2C3N = 119.0(3)°, and ∠C3NO = 109.4(2)°. The ∠C2C3N, ∠C1C2C3, and rg(C3–N) values of the synperiplanar form (122.6(6)°, 112.6(6)°, and 1.291(3) Å, respectively) are not equal to those of the anticlinal form.
Separation of the Diffusion Potential within a Membrane and the Donnan Potential on the Basis of a Measurement of Transient Membrane Potentials
Authors: Nomura Kazuo 
Published: June 2006

Abstract
In the perfluoro carboxylate cation exchange membrane–aqueous electrolyte systems, two steps appeared in the time course of the membrane potential in response to a pH jump in the external solution. LiCl, NaCl, and KCl were used as the electrolytes. According to the experimentally observed curve of the potential transient, the membrane potential was divided in two portions: the potential difference at the membrane/solution interface (Donnan potential) and the intramembrane diffusion potential. It was found that the differences among the total membrane potentials for three kinds of alkali metal ion systems were mainly attributed to the generation process of the diffusion potential within the membrane. The pH dependencies of the Donnan potential and intramembrane diffusion potential were calculated on the basis of a theory starting at the Nernst–Planck equation for the ion diffusion. Calculations were carried out taking into account the association/dissociation reaction of hydrogen ions and ion exchange groups and the heterogeneous structure of the membrane. By fitting the theoretical equations to the experimental results, the best-fitting values of relative mobility of ion and the dissociation constant of COOH group in the membrane were obtained.
Simple and Rapid Determination of the Activation Parameters of Organic Reactions by Temperature-Dependent NMR Spectroscopy II. Application to Reversible Reactions
Authors: Satoh Masahiro , Hirota Minoru 
Published: June 2006

Abstract
A non-isothermal (NIT) method for evaluating the activation enthalpies and entropies of reactions in solutions was applied to several reversible reactions. This was realized by a stepwise elevation of the temperature of a reaction system using a variable-temperature apparatus comprising on NMR spectrometer and a quick collection of FID (free induction decay) at every plateau of the step. The rate from NIT experiments agreed well with the previously measured rates by the conventional methods.