bluuebunny/crossref_metadata_2025_split huggingface dataset:
Half‐Sandwich Rhodium (and Iridium) Complexes as Enantioselective Catalysts for the 1,3‐Dipolar Cycloaddition of 3,4‐Dihydroisoquinoline N‐Oxide to Methacrylonitrile
Authors: Carmona Daniel , Lamata M. Pilar , Viguri Fernando , Rodríguez Ricardo , Lahoz Fernando J. , Oro Luis A. 
Published: October 2007

AbstractCationic half‐sandwich complexes containing the [(η5‐C5Me5)M(Diphos*)] moiety (M=Rh, Ir; Diphos*=chiral diphosphine ligand) catalyze the cycloaddition of the nitrone 3,4‐dihydroisoquinoline N‐oxide (A) to methacrylonitrile (B) with excellent regio and endo selectivity and low‐to‐moderate enantioselectivity. The most active and selective catalyst, (SRh,RC)‐[(η5‐C5Me5)Rh{(R)‐Prophos)} (NC(Me)CCH2)](SbF6)2, has been isolated and fully characterized including the determination of the molecular structure by X‐ray diffraction. The R‐at‐metal epimers of the complexes [(η5‐C5Me5)M{(R)‐Prophos)}(NC(Me)CCH2)](SbF6)2 (M=Rh, Ir) isomerize to the corresponding S‐at‐metal diastereomers. The stoichiometric cycloaddition of A with B is catalyzed by diastereopure (SM,RC)‐[(η5‐C5Me5)M{(R)‐Prophos)}(NC(Me)CCH2)](SbF6)2 with perfect regio and endo selectivity and very good (up to 95 %) ee. The catalyst can be recycled up to nine times without significant loss of either activity or selectivity.
Geometric Formalism for DNA Quadruplex Folding
Authors: Webba da Silva Mateus 
Published: October 2007

AbstractUnderstanding the control of self‐assembly and stereochemical properties of DNA higher order architectural folds is of fundamental importance in biology as well as biochemical technological applications. Guanine‐rich DNA sequences can form tetrahelical architectures termed quadruplexes. A formalism is presented describing the interdependency of a set of structural descriptors as a geometric basis for folding of unimolecular quadruplex topologies. It represents a standard for interpretation of structural characteristics of quadruplexes, and is comprehensive in explicitly harmonizing the results of published literature with a unified language. The formalism is a fundamental step towards prediction of unimolecular quadruplex folding topologies from primary sequence.
1,4‐Pentenyne as a Five‐Carbon Synthon for Efficient and Selective Syntheses of Natural Products Containing 2,4‐Dimethyl‐1‐penten‐1,5‐ylidene and Related Moieties by Means of Zr‐Catalyzed Carboalumination of Alkynes and Alkenes
Authors: Zhu Gangguo , Negishi Ei‐ichi 
Published: October 2007

AbstractTwo highly efficient protocols for enantioselective synthesis of 2,4‐dimethyl‐1‐penten‐1,5‐ylidene derivatives involve the combined use of the Zr‐catalyzed methylalumination of alkynes (ZMA) and the Zr‐catalyzed asymmetric carboalumination of alkenes (ZACA). The ZMA/ZACA protocol has been applied to the synthesis of a nafuredin intermediate 14 and a potential intermediate 18 for milbemycin β3, while the ZACA/ZMA protocol has been applied to the synthesis of a (−)‐bafilomycin A1 intermediate 25.
Antiproliferative Activity, Cell‐Cycle Dysregulation, and Cellular Differentiation: Salicyl‐ and Catechol‐Derived Acyclic 5‐Fluorouracil O,N‐Acetals against Breast Cancer Cells
Authors: Marchal Juan A. , Rodríguez‐Serrano Fernando , Caba Octavio , Aránega Antonia , Gallo Miguel A. , Espinosa Antonio , Campos Joaquín M. 
Published: October 2007

AbstractHerein we report the preparation and biological activity of three compounds with the general formula 1‐[2‐(5‐substituted‐2‐hydroxybenzyloxy)‐1‐methoxyethyl]‐5‐fluorouracil. A catechol‐derived compound such as 1‐[3‐(2‐hydroxyphenoxy)‐1‐methoxypropyl]‐5‐fluorouracil and two salicyl‐derived compounds such as (Z)‐1‐[4‐(2‐hydroxyphenyl)‐1‐methoxybut‐3‐enyl]‐5‐fluorouracil [(Z)‐11] and its dihydrogenated derivative 1‐[4‐(2‐hydroxyphenyl)‐1‐methoxybutyl]‐5‐fluorouracil were prepared to complete the set of six O,N‐acetals. The most active compound against the MCF‐7 breast cancer cell line was (Z)‐11: IC50=9.40±0.64 μM. Differentiated breast cancer cells generate fat deposits in the cytoplasm. MCF‐7 cells treated with (Z)‐11 underwent an increase in lipid content relative to control cells after three days of treatment. Our results suggest that there may be significant potential advantages in the use of this new differentiating agent for the treatment of breast cancer.
Design and evaluation of a low field system for hyperpolarized 3‐He gas imaging of neonatal lungs
Authors: Krjukov E. , Fichele S. , Wild J.M. , Paley M.N.J. 
Published: October 2007

Abstract3‐Helium can be optically pumped with laser light to produce exceptionally high nuclear polarization, which is independent of field strength. This increased polarization can allow imaging at low and ultra low field strengths, while still obtaining high signal‐to‐noise ratio. Low field magnets can be built for a fraction of the cost of high field clinical scanners and feature greatly reduced susceptibility artifact and less RF power requirement than higher field systems. Further advantage can be achieved by combination of hyperpolarized gas with parallel imaging methods. A particularly promising target for 3‐He imaging is the premature neonatal lung, where new ways to visualize impaired lung development would be very useful clinically. Overall safety is much improved operating at ultra low fields and there is good compatibility with standard neonatal physiological monitoring equipment. A six coil, open access resistive magnet operating at fields up to 0.015 T with unforced air cooling and sized to allow imaging of the neonatal lungs has been designed and built. A multi‐channel broadband spectrometer and software system has also been designed, constructed, and interfaced to the magnet. Both proton and hyperpolarized helium images have been acquired from test objects using the same four channel radiofrequency coil array, operating at a frequency of 450 kHz, by adjusting the magnetic field. The system is now in final preparation for studies of neonatal lungs in the Neonatal Intensive Care Unit. © 2007 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 31B: 209–217, 2007
Modal analysis of a multilayered gradient coil insert in a 4‐T MRI scanner
Authors: Wang Fenglin , Mechefske Chris 
Published: October 2007

AbstractIn ultrahigh field strength Magnetic Resonance Imaging (MRI), the pulsed electrical currents passing through gradient coil windings cause powerful alternating forces that act on the gradient coil structure and create structural vibration and consequential acoustic noise (as high as 130 dB). The dynamic response of the gradient coil cylinder largely determines the acoustic noise generated in terms of frequency components, sound pressure levels (SPL), and the spatial distribution within the bore of the scanner. The objective of this article is to characterize the dynamic behavior of a real (multilayered) gradient coil insert in a 4‐T MRI scanner (from 200 to 3,000 Hz). The simply supported (assembly condition) and free–free (modal testing) condition are investigated in the dynamic analysis. In‐situ vibration testing, modal testing, and numerical analyses are applied to uncover the dynamic features. The results indicate that bending modes in combination with different specific free–free and simply supported radial mode shapes provide the fundamental characteristics of the dynamic behavior of the gradient coil cylinder in the frequency range tested. The change in dominant bending mode as a function of scanning input frequency was also studied. © 2007 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 31B: 237–254, 2007
Design and performance of a DNP prepolarizer coupled to a rodent MRI scanner
Authors: Comment A. , van den Brandt B. , Uffmann K. , Kurdzesau F. , Jannin S. , Konter J.A. , Hautle P. , Wenckebach W.Th. , Gruetter R. , van der Klink J.J. 
Published: October 2007

AbstractFor most of the last forty years, the techniques of Dynamic Nuclear Polarization (DNP) have been confined to particle‐physics laboratories building polarized targets, but recently it has been shown that samples similar to a solid target can be transformed into room temperature liquid solutions while retaining a high nuclear polarization. This method of “hyperpolarization” is of interest in NMR/MRI/MRS. We describe a 3.35 T DNP/9.4 T MRI installation based on a continuous‐flow cryostat, using a standard wide‐bore low‐field NMR magnet as prepolarizer magnet and a widely available radical as polarizing agent. The interfacing to a rodent scanner requires that the infusion of the polarized solution in the animal be remotely controlled, because of limited access inside the magnet bore. Physiological constraints on the infusion rate can be a serious source of polarization loss, and the discussion of efficiency is therefore limited to that of the prepolarizer itself, i.e., the spin temperatures obtained in the solid state. To put our results in context, we summarize data obtained in targets with different types of radicals, and provide a short review of the DNP mechanisms needed in their discussion. © 2007 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 31B: 255–269, 2007
Efficient method for parameter estimation of MRS signal using decimation and prior knowledge
Authors: Zeng Weiming 
Published: October 2007

AbstractMagnetic resonance spectroscopy (MRS) signals are often characterized by a low signal‐to‐noise ratio and overlapping peaks. Under these circumstances simple signal processing methods are not adequate. Using the different decimated sequences of original MRS signal and prior knowledge of frequency differences and equal damping factors, an efficient parameter estimation method is presented in this article. The experimental results show that among three parameter estimation methods of HTLS, HTLSPK (Δfdeq) and the novel method, the last method obviously has the best performance with a lowest failure rate and a highest estimation accuracy. Even if some inaccuracy of prior knowledge is considered, the novel method also shows some advantages. © 2007 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 31B: 270–277, 2007
Infinite time aggregation for the critical Patlak‐Keller‐Segel model in ℝ2
Authors: Blanchet Adrien , Carrillo José A. , Masmoudi Nader 
Published: October 2007

AbstractWe analyze the two‐dimensional parabolic‐elliptic Patlak‐Keller‐Segel model in the whole Euclidean space ℝ2. Under the hypotheses of integrable initial data with finite second moment and entropy, we first show local‐in‐time existence for any mass of “free‐energy solutions,” namely weak solutions with some free‐energy estimates. We also prove that the solution exists as long as the entropy is controlled from above. The main result of the paper is to show the global existence of free‐energy solutions with initial data as before for the critical mass 8π/χ. Actually, we prove that solutions blow up as a delta Dirac at the center of mass when t → ∞ when their second moment is kept constant at any time. Furthermore, all moments larger than 2 blowup as t → ∞ if initially bounded. © 2007 Wiley Periodicals, Inc.
WdCM: a workday calendar model for workflows in service grid environments
Authors: Liu Jianxun , Zhou Chunjie , Chen Jinjun 
Published: November 2007

AbstractThe time model for business cooperation across organizations and in business service grid has a special and important requirement, i.e. workday calendar model (WdCM). Workflow plays an important role in modelling business processes across multi‐enterprises or in service grid environments. However, current research in workflow time models does not pay sufficient attention to the differences in workday calendar between individual organizations. This paper aims to solve this problem by clarifying some basic concepts involved in the workday calendar models and presenting an XML‐based framework for workday calendar expressions, i.e. WdCM. Based on this WdCM, temporal constraints and the time optimization issue of workflow processes are investigated. Finally, a case study is analysed to demonstrate the feasibility of our workday calendar model. Copyright © 2007 John Wiley & Sons, Ltd.
Semantic patterns for user‐interactive question answering
Authors: Hao Tianyong , Hu Dawei , Wenyin Liu , Zeng Qingtian 
Published: November 2007

AbstractA new type of semantic pattern is proposed in this paper, which can be used by users to post questions and answers in user‐interactive question answering (QA) systems. The necessary procedures of using semantic patterns in a QA system are also presented, which include question structure analysis, pattern matching, pattern generation, pattern classification and answer extraction. Both the manual creation method and the automatic generation method are proposed for patterns for different applications. A pattern instantiation level metrics is also presented for the predication of the quality of generated or learned patterns. We implemented a user interface for using the semantic pattern in our QA system, which allows users to effectively post and answer questions. Copyright © 2007 John Wiley & Sons, Ltd.
Detection of mycoplasmas in goat milk by flow cytometry
Authors: Assunção Patricia , Davey Hazel M. , Rosales Ruben S. , Antunes Nuno T. , de la Fe Christian , Ramirez Ana S. , de Galarreta Carlos M. Ruiz , Poveda Jose B. 
Published: October 2007

AbstractThe detection of mycoplasma in milk can be performed by either culture techniques or polymerase chain reaction (PCR) based methods. Although PCR can reduce the average diagnostic time to 5 h in comparison with the several days for the isolation of the agent, there is still a need to develop methods, which could give earlier results. For this purpose, we tested the ability of flow cytometry (FC) to detect mycoplasmas in milk samples. Milk samples inoculated with four different mycoplasmas, Mycoplasma agalactiae, Mycoplasma putrefaciens, Mycoplasma capricolum subsp. Capricolum, or Mycoplasma mycoides subsp. mycoides large‐colony type, known to cause contagious agalactia in goats, were stained with the DNA stain SYBR Green I and analyzed by FC. Three goat milk samples, from which mycoplasmas have been isolated in broth medium were also analyzed. All mycoplasmas were easily distinguished from debris of milk samples, but it was not possible to distinguish between the different mycoplasma species. In our conditions, the detection limit of the technique was of the order of 103–104 cells ml−1. Furthermore, mycoplasmas were also distinguished from Staphylococcus aureus. FC together with SYBR Green I was able to distinguish between mycoplasma cells and debris present in milk samples and gave results in 20–30 min. This is an important first step in developing a robust, routine flow cytometric method for the detection of mycoplasmas in milk samples. © 2007 International Society for Analytical Cytology
Hypertriglyceridaemic waist phenotype criteria and prevalent metabolic triad in women
Authors: Gazi Irene F. , Milionis Haralampos J. , Filippatos Theodosios D. , Tsimihodimos Vasilis , Kostapanos Michael S. , Doumas Michael , Tselepis Alexandros D. , Elisaf Moses 
Published: October 2007

AbstractBackgroundTo assess the metabolic profile and the prevalence of the metabolic triad (i.e. hyperinsulinaemia, hyperapobetalipoproteinaemia, and decreased low‐density lipoprotein particle size) in women characterized by the hypertriglyceridaemic waist (HTGW) phenotype and to identify cut‐off values for triglycerides and waist circumference, effectively discriminating women with the metabolic triad.MethodsTwo hundred and twenty‐eight female subjects without any history of vascular disease or diabetes mellitus attending an Outpatient Lipid Clinic setting at the University Hospital of Ioannina, Greece were studied.ResultsCurrently available HTGW criteria for women were unable to detect any significant differences in the metabolic profile either in the pre‐ or post‐menopausal women, and proved similar in terms of sensitivity and specificity in identifying women with the metabolic triad. A cut‐off value of 1.26 mmol/L for triglycerides and 84.5 cm for waist circumference were determined by Receiver‐operating Curve evaluation. Women with both triglycerides and waist circumference above these thresholds had four‐fold higher odds of presenting with the metabolic triad compared with women with non‐HTGW phenotype.ConclusionsA HTGW phenotype definition of 1.26 mmol/L for triglycerides and 84.5 cm for waist circumference may effectively identify Mediterranean women with the atherogenic metabolic triad. Whether these criteria are also associated with a higher incidence of vascular disease and/or new‐onset diabetes in women remains to be investigated. Copyright © 2007 John Wiley & Sons, Ltd.
Decreased in vivo oxidative stress and decreased platelet activation following metformin treatment in newly diagnosed type 2 diabetic subjects
Authors: Formoso Gloria , De Filippis Elena A. , Michetti Noemi , Di Fulvio Patrizia , Pandolfi Assunta , Bucciarelli Tonino , Ciabattoni Giovanni , Nicolucci Antonio , Davì Giovanni , Consoli Agostino 
Published: October 2007

AbstractBackgroundIn type 2 diabetes, metformin reduces cardiovascular risk beyond the effect of glycaemic control. Since oxidative stress and the consequent enhanced platelet activation contribute to accelerated atherosclerosis in diabetes, we hypothesized that metformin could reduce oxidative stress in this condition.MethodsWe randomized 26 newly diagnosed type 2 diabetic subjects to assume either metformin (M, n = 13) or gliclazide (G, n = 13) for 12 weeks. Drugs were titrated as needed to achieve good glycaemic control. Before and after treatment, we determined blood glucose, insulin, HbA1c, vitamin A and E levels and 8‐iso‐PGF2α and 11‐dehydro‐thromboxane B2 urinary excretion, an in vivo oxidative stress and a thromboxane‐dependent platelet activation marker, respectively.ResultsNotwithstanding a comparable improvement in metabolic control, 8‐iso‐PGF2α (M from 708 ± 32 to 589 ± 45 pg/mg cr, p < 0.001; G from 646 ± 80 to 665 ± 79, pg/mg cr, p = ns) and 11‐dehydro‐thromboxane B2 (M from 2190 ± 196 to 1753 ± 150 pg/mg cr, p < 0.05; G from 2048 ± 202 to 1923 ± 223, pg/mg cr, p = ns) urinary excretion decreased after metformin but not after gliclazide treatment. After metformin, vitamin A and E levels significantly increased while they remained unchanged after gliclazide.ConclusionsThese data suggest that metformin could improve oxidative stress, preserve antioxidant function and restrain platelet activation in type 2 diabetes. Copyright © 2007 John Wiley & Sons, Ltd.
Genetic screen for regulators of ind expression identifies shrew as encoding a novel twisted gastrulation‐like protein involved in Dpp signaling
Authors: Bonds Morgan , Sands Jennifer , Poulson Will , Harvey Canda , Von Ohlen Tonia 
Published: October 2007

AbstractInitiation and refinement of expression of the Ind homeodomain protein in the Drosophila embryo is coordinately regulated by global dorsoventral patterning pathways Dorsal, Egfr, and Dpp, and well as by Vnd, which positions the ventral boundary of Ind. Therefore, we set out to look for novel regulators of dorsoventral patterning by screening the Exelixis deficiency collection for modified expression of Ind. Indeed, we found deficiencies that remove components of the known signaling pathways had altered or lost ind expression. These findings included deficiencies that remove screw, dpp, and egfr as well as deficiencies that remove ind itself. In addition, we found several deficiencies that had altered or loss of ind expression. We also observed phenotypes suggestive of dorsoventral patterning defects such as twisting during gastrulation, and defects associated with loss of dorsal specification. These include a pair of overlapping deficiencies that produced ventralized embryos. We find that transheterozygotes of these two deficiencies are also ventralized. There are seven genes common to both deficiencies, including CG11582, which encodes a twisted gastrulation‐like protein. These two deficiencies are also allelic with shrew mutations. Here, we present data supporting the conclusion that CG11582 is the gene affected in shrew mutants. Developmental Dynamics 236:3524–3531, 2007. © 2007 Wiley‐Liss, Inc.
Identification and expression of XRTN1‐A and XRTN1‐C in Xenopus laevis
Authors: Park Edmond Changkyun , Shim Sangwoo , Han Jin‐Kwan 
Published: October 2007

AbstractReticulon1, also known as neuroendocrine‐specific protein, belongs to the reticulon (RTN) family, whose members possess a conserved reticulon domain and are associated with the endoplasmic reticulum (ER) membrane. Here, we report cloning and expression of Xenopus homologues of Reticulon1‐A (XRTN1‐A) and ‐C (XRTN1‐C). XRTN1‐A and ‐C contain an open reading frame of 752 and 207 amino acids, respectively, each containing a conserved reticulon domain. Sequence analysis shows that XRTN1 proteins have an ER membrane retention signal and four putative membrane‐spanning domains. Reverse transcription‐polymerase chain reaction and whole‐mount in situ hybridization showed that XRTN1‐A is expressed in early neural precursors and differentiating neuronal populations, including the trigeminal placode, olfactory placode, lateral line placode, and otic vesicle. XRTN1‐C is expressed in the developing brain and spinal cord. We found that XRTN1‐C protein is localized to the ER of Xenopus and mammalian cells and the granules in neurites of primary neurons of the Xenopus spinal cord and rat hippocampus. We also showed that XRTN1‐C protein is detected in the heavy membrane fraction, which contains lysosomal and ER‐resident proteins, as well as in the nucleus and polysomal fractions of the Xenopus embryo. Finally, we showed that thyroid hormone specifically down‐regulates XRTN1‐A mRNA in the head of premetamorphic Xenopus tadpoles. Our work characterizes the intracellular roles of XRTN1 during Xenopus neural development. Developmental Dynamics 236:3545–3553, 2007. © 2007 Wiley‐Liss, Inc.
An olig2 reporter gene marks oligodendrocyte precursors in the postembryonic spinal cord of zebrafish
Authors: Park Hae‐Chul , Shin Jimann , Roberts Randolph K. , Appel Bruce 
Published: October 2007

AbstractContinuous production of new neurons and glia in adult mammals occurs within specialized proliferation zones of the forebrain. Neural cell proliferation and neurogenesis is more widespread in adult amphibians, reptiles, and fish but the identity of neural stem cell populations in these organisms has not been fully described. We investigated expression of a reporter gene driven by olig2 regulatory DNA at postembryonic stages in zebrafish. We show that olig2 expression marks a discrete population of spinal cord radial glia in larvae and adults that divide continuously. olig2+ radial glia have hallmarks of stem cells and their divisions appear to be asymmetric, producing new oligodendrocytes but not neurons or astrocytes. Developmental Dynamics 236:3402–3407, 2007. © 2007 Wiley‐Liss, Inc.
1,3‐Dipolar Cycloadditions of N‐Benzyl‐2,3‐O‐isopropylidene‐D‐glyceraldehyde Nitrone to Methoxyallene – Control of Site‐ and Diastereoselectivity of Isoxazolidine Formation by Lewis Acids
Authors: Dugovič Branislav , Fišera Lubor , Reißig Hans‐Ulrich 
Published: October 2007

AbstractThe siteselectivity of cycloadditions of the D‐glyceraldehyde‐derived nitrone 1 and methoxyallene (2) is strongly influenced by Lewis acids. The uncatalyzed reaction results in the formation of isomeric isoxazolidines 3a–3d and 4a–4c, whereas in the presence of different Lewis acids exclusive formation of 4‐methylene‐substituted isoxazolidines 4a–4d is observed. Furthermore, the diastereofacial selectivity of the methoxyallene addition to nitrone 1 can be controlled, thus giving rise to both diastereomeric isoxazolidines 3,4′‐anti‐4 or 3,4′‐syn‐4, just by employing different Lewis acids. The redox ring‐opening of isoxazolidines 4 using Murahashi's protocol yields α‐methylene‐β‐amino acid esters 5a,b and 7a,b.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)