bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and In Vitro Protozoocidal Evaluation of Novel Diazabicyclic Tropolone Derivatives
Authors: Khrizman Alexander , Slack Rachel D. , Remsing Richard C. , Little Susan , Yardley Vanessa , Moyna Guillermo 
Published: October 2007

AbstractThe synthesis and in vitro antiparasitic activity of twenty‐seven novel diazabicycles based on tropolone ethers is presented. The compounds can be readily prepared by means of a high‐yielding hetero Diels–Alder reaction using simple and readily available starting materials. Several of the new diazabicycles have in vitro activities against Trypanosoma cruzi, Leishmania donovani, Trypanosoma brucei rhodesiense, and chloroquine‐resistant Plasmodium falciparum that are comparable or superior to those of currently employed protozoocidal agents.
Design and Synthesis of Isocyanide Ligands for Catalysis: Application to Rh‐Catalyzed Hydrosilylation of Ketones
Authors: Ito Hajime , Kato Takayuki , Sawamura Masaya 
Published: October 2007

AbstractNew isocyanide ligands with meta‐terphenyl backbones were synthesized. 2,6‐Bis[3,5‐bis(trimethylsilyl)phenyl]‐4‐methylphenyl isocyanide exhibited the highest rate acceleration in rhodium‐catalyzed hydrosilylation among other isocyanide and phosphine ligands tested in this study. 1H NMR spectroscopic studies on the coordination behavior of the new ligands to [Rh(cod)2]BF4 indicated that 2,6‐bis[3,5‐bis(trimethylsilyl)phenyl]‐4‐methylphenyl isocyanide exclusively forms the biscoordinated rhodium–isocyanide complex, whereas less sterically demanding isocyanide ligands predominantly form tetracoordinated rhodium–isocyanide complexes. FTIR and 13C NMR spectroscopic studies on the hydrosilylation reaction mixture with the rhodium–isocyanide catalyst showed that the major catalytic species responsible for the hydrosilylation activity is the Rh complex coordinated with the isocyanide ligand. DFT calculations of model compounds revealed the higher affinity of isocyanides for rhodium relative to phosphines. The combined effect of high ligand affinity for the rhodium atom and the bulkiness of the ligand, which facilitates the formation of a catalytically active, monoisocyanide–rhodium species, is proposed to account for the catalytic efficiency of the rhodium–bulky isocyanide system in hydrosilylation.
Economic impacts of bio‐refinery and resource cascading systems: An applied general equilibrium analysis for Poland
Authors: Ignaciuk Adriana M. , Sanders Johan 
Published: October 2007

AbstractDue to more stringent energy and climate policies, it is expected that many traditional chemicals will be replaced by their biomass‐based substitutes, bio‐chemicals. These innovations, however, can influence land allocation since the demand for land dedicated to specific crops might increase. Moreover, it can have an influence on traditional agricultural production. In this paper, we use an applied general equilibrium framework, in which we include two different bio‐refinery processes and incorporate so‐called cascading mechanisms. The bio‐refinery processes use grass, as one of the major inputs, to produce bio‐nylon and propane‐diol (1,3PDO) to substitute currently produced fossil fuel‐based nylon and ethane‐diol. We examine the impact of specific climate policies on the bioelectricity share in total electricity production, land allocation, and production quantities and prices of selected commodities. The novel technologies become competitive, with an increased stringency of climate policies. This switch, however, does not induce a higher share of bioelectricity. The cascade does stimulate the production of bioelectricity, but it induces more of a shift in inputs in the bioelectricity sector (from biomass to the cascaded bio‐nylon and 1, 3PDO) than an increase in production level of bioelectricity. We conclude that dedicated biomass crops will remain the main option for bioelectricity production: the contribution of the biomass systems remains limited. Moreover, the bioelectricity sector looses a competition for land for biomass production with bio‐refineries.
Biobutanol: An attractive biofuel
Authors: Dürre Peter 
Published: October 2007

AbstractBiofuels are an attractive means to prevent a further increase of carbon dioxide emissions. Currently, gasoline is blended with ethanol at various percentages. However, butanol has several advantages over ethanol, such as higher energy content, lower water absorption, better blending ability, and use in conventional combustion engines without modification. Like ethanol, it can be produced fermentatively or petrochemically. Current crude oil prices render the biotechnological process economic again. The best‐studied bacterium to perform a butanol fermentation is Clostridium acetobutylicum. Its genome has been sequenced, and the regulation of solvent formation is under intensive investigation. This opens the possibility to engineer recombinant strains with superior biobutanol‐producing ability.
Monolayer cell expansion conditions affect the chondrogenic potential of adipose‐derived stem cells
Authors: Estes Bradley T. , Diekman Brian O. , Guilak Farshid 
Published: October 2007

AbstractAdipose‐derived stem cells (ASCs) are an abundant, readily available population of multipotent progenitor cells that reside in adipose tissue. Isolated ASCs are typically expanded in monolayer on standard tissue culture plastic with a basal medium containing 10% fetal bovine serum. However, recent data suggest that altering the monolayer expansion conditions by using suspension culture plastic, adding growth factors to the medium, or adjusting the seeding density may affect the self‐renewal rate, multipotency, and lineage‐specific differentiation potential of the ASCs. We hypothesized that variation in any of these expansion conditions would influence the chondrogenic potential of ASCs. ASCs were isolated from human liposuction waste tissue and expanded through two passages with different tissue culture plastic, feed medium, and cell seeding densities. Once expanded, the cells were cast in an agarose gel and subjected to identical chondrogenic culture conditions for 7 days, at which point cell viability, radiolabel incorporation, and gene expression were measured. High rates of matrix synthesis upon chondrogenic induction were mostly associated with smaller cells, as indicated by cell width and area on tissue culture plastic, and it appears that expansion in a growth factor supplemented medium is important in maintaining this morphology. All end‐point measures were highly dependent on the specific monolayer culture conditions. These results support the hypothesis that monolayer culture conditions may “prime” the cells or predispose them towards a specific phenotype and thus underscore the importance of early culture conditions in determining the growth and differentiation potential of ASCs. Biotechnol. Bioeng. 2008; 99; 986–995. © 2007 Wiley Periodicals, Inc.
Study of Modification Pattern–RNAi Activity Relationships by Using siRNAs Modified with 4′‐Thioribonucleosides
Authors: Hoshika Shuichi , Minakawa Noriaki , Shionoya Aki , Imada Keiko , Ogawa Naoki , Matsuda Akira 
Published: October 2007

AbstractA detailed study of the modification pattern–RNAi activity relationships by using siRNAs that are modified with 4′‐thioribonucleosides has been carried out against photinus luciferase and renilla luciferase genes in cultured mammalian NIH/3T3, HeLa, and MIA PaCa‐2 cell lines. When the photinus luciferase gene was targeted, all of the modified siRNAs showed activity equal to, or less than the unmodifed siRNA. In contrast, all modified siRNAs that have a similar modification pattern showed activity equal to or much higher than the unmodified siRNA when tested with the renilla luciferase gene. These results indicated that siRNAs such as RNA33 and RNA53, which each have four residues of the 4′‐thioribonucleoside unit on both ends of the sense strand and four residues on the 3′‐end of the antisense strand, were the most effective. Accordingly, we succeeded in developing modified siRNAs that have the greatest number of 4′‐thioribonucleosides without loss of RNAi activity, and that exhibit potent RNAi activity against two target genes in three different cell lines. Our findings also indicate the significance of target sequences and cell lines when RNAi activity is compared with that of the unmodified siRNA.
Randomized, double‐blind, multicenter study of the polymer‐based 17‐β estradiol‐eluting stent for treatment of native coronary artery lesions: Six‐month results of the ETHOS I trial
Authors: Abizaid Alexandre , Chaves Áurea J. , Leon Martin B. , Hauptmann Karl , Mehran Roxana , Lansky Alexandra J. , Baumbach William , Shankar Hari , Muller Ralf , Feres Fausto , Sousa Amanda G.M.R. , Sousa J. Eduardo , Grube Eberhard 
Published: October 2007

AbstractObjectives: The ETHOS I trial was the first in‐human experience evaluating the safety and efficacy of two different release formulations of the 17‐β estradiol‐eluting R‐Stent™ versus uncoated control stents for the treatment of patients with single de novo native coronary lesions. Background: Estrogens were reported to inhibit neointimal proliferation and to accelerate endothelial regeneration after coronary angioplasty and thus could be an ideal compound to deliver on a stent for the purpose of reducing in‐stent restenosis. Methods: Ninety‐five patients were randomized to receive a slow‐release (n = 32) or the moderate release (n = 31) formulations or the bare metal stent (n = 32). The primary end point was the 6‐month percent in‐stent volume obstruction by intravascular ultrasound (IVUS). Results: Diabetes was present in 29.5% of patients; the mean reference vessel diameter was 2.90 mm; and the mean lesion length was 13.5 mm. Primary endpoint, 6‐month percent in‐stent volume obstruction by IVUS, did not differ significantly between the 3 groups (31% ± 14%, 33% ± 11%, and 31% ± 14%, P = 0.83). Secondary endpoints also did not differ significantly between the groups including 6‐month rates of in‐lesion binary angiographic restenosis (13.3%, 14.3%, and 12.5%, P = 0.98), in‐stent late loss (0.82 ± 0.49 mm, 0.86 ± 0.53 mm, and 0.84 ± 0.46 mm, P = 0.97), target lesion revascularization (12.5%, 6.9%, and 6.5%, P = 0.64), and major adverse cardiac events (18.8%, 10.3%, and 6.5%, P = 0.31). Conclusions: In this first‐in‐man randomized trial, the 17‐β estradiol‐eluting R‐Stent™, in either slow‐ or moderate‐release formulations, was well‐tolerated, but showed no benefit for treatment of coronary lesions when compared to controls. © 2007 Wiley‐Liss, Inc.
Dislodged caval stent in right pulmonary artery
Authors: Chiu Kuan‐Ming , Chu Shu‐Hsun , Chan Chih‐Yang 
Published: October 2007

AbstractPercutaneous intervention for central vein occlusion is getting popular. Self‐expandable stent is user‐friendly in this field, however, jump‐out displacement may happen. An 82‐year‐old woman with end‐stage renal disease and central vein occlusion underwent central vein stenting. Dislodgement of the self‐expandable stent was encountered. Migration into right ventricle and subsequently right pulmonary artery was noted. Chest films of this rare condition were reported. © 2007 Wiley‐Liss, Inc.
Long‐term effects of balloon angioplasty on left ventricular hypertrophy in adolescent and adult patients with native coarctation of the aorta. Up to 18 years follow‐up results
Authors: Hassan Walid , Awad Mahmoud , Fawzy Mohamed Eid , Omrani Ahmad Al , Malik Shahid , Akhras Nathem , Shoukri Mohamed 
Published: October 2007

AbstractBackground:Little is known regarding the long‐term follow‐up results of balloon angioplasty (BA) for patients with native aortic coarctation (AC) on left ventricular hypertrophy (LVH) regression.Objectives:The purpose of this study was to define the long‐term effect of BA of AC on LVH in adolescent and adult patients.Methods:Follow‐up data of 53 patients (36 male) mean age 24 ± 9 years undergoing BA for discrete AC at median interval of 11.8 years (range 4–18 years) including cardiac catheterization, magnetic resonance imaging, and Echocardiography form the basis of this study. Patients were divided into two groups at 1 year after BA based on absence (group A) or presence (group B) of persistent hypertension and need for medication.Results:Forty‐nine patients had baseline LVH, BA produced an immediate reduction in peak AC gradient from 66 ± 23 mm Hg (95% confidence interval [CI]: 59.5–72.7) to 10.8 ± 7 mm Hg (95% CI: 8.8–12.5) (P < 0.0001). Follow‐up catheterization 12 months later revealed a residual gradient of 6.2 ± 6 mm Hg (95% CI: 4.4–7.9) (P < 0.001). The blood pressure had normalized without medication in 38 of the 49 patients (165 ± 17 to 115 ± 10 mm Hg). Left ventricular mass index (LVMI) decreased significantly (>20% decrease LVMI from baseline) in 48 patients (98%) at median interval 1.4 years (range 0.5–3 years) post BA, group A (38 patients) LVMI decreased from 132 ± 30.7 g/m2 (95% CI: 122–141.9) to 86 ± 19.9 g/m2 (95% CI: 79.5–92.5) (P < 0.0001). Similarly, in 10 patients (group B) the LVMI decreased from 157 ± 38.7 g/m2 (95% CI: 127–185) to 102 ± 29 g/m2 (95% CI: 105–151) (P < 0.0001) at follow‐up. Mild (<20% decrease in LVMI) regressions were noted in one patient from group B. There was no progression to LVH in the four patients who had normal baseline LVMI.Conclusion:(1) Long‐term results of BA for discrete AC are excellent and should be considered as first option for treatment of this disease; (2) Regression of LVH (≥20% reduction in LVMI) occurred in 98% of patients after BA. © 2007 Wiley‐Liss, Inc.
Living Photolytic Ring‐Opening Polymerization of Amino‐Functionalized [1]Ferrocenophanes: Synthesis and Layer‐by‐Layer Self‐Assembly of Well‐Defined Water‐Soluble Polyferrocenylsilane Polyelectrolytes
Authors: Wang Zhuo , Masson Georgeta , Peiris Frank C. , Ozin Geoffrey A. , Manners Ian 
Published: October 2007

AbstractFacile synthetic routes have been developed that provide access to cationic and anionic water‐soluble polyferrocenylsilane (PFS) polyelectrolytes with controlled molecular weight and narrow polydispersity. Living photolytic ring‐opening polymerization of amino‐functionalized [1]ferrocenophane (fc) monomers [fcSiMe{CCCH2N(SiMe2CH2)2}] (3), [fcSi{CCCH2N(SiMe2CH2)2}2] (10), [fcSiMe(CCCH2NMe2)] (14), and [fcSiMe(p‐C6H4CH2NMe2)] (20) yielded the corresponding polyferrocenylsilanes [(fcSiMe{CCCH2N(SiMe2CH2)2})n](5), [(fcSi{CCCH2N(SiMe2CH2)2}2)n] (11), [{fcSiMe(CCCH2NMe2)}n] (15), and [{fcSiMe(p‐C6H4CH2NMe2)}n] (21) with controlled architectures. Further derivatization of 5, 15, and 21 generated water‐soluble polyelectrolytes [(fcSiMe{CCCH2N(CH2CH2CH2SO3Na)2})n] (6), [{fcSiMe(CCCH2NMe3OSO3Me)}n] (7), and [{fcSiMe(p‐C6H4CH2NMe3OSO3Me)}n] (22), respectively. The polyelectrolytes were readily soluble in water and NaCl aqueous solutions, with 6 and 22 exhibiting long‐term stability in aqueous media. The PFS materials 6 and 22, have been utilized in the layer‐by‐layer (LbL) self‐assembly of electrostatic superlattices. Our preliminary studies have indicated that films made from controlled low molecular‐weight PFSs possess a considerably thinner bilayer thickness and higher refractive index than those made from PFSs that have an uncontrolled high molecular‐weight. These results suggest that the structure and optical properties of LbL ultra‐thin films can be tuned by varying polyelectrolyte chain length. The water‐soluble low molecular weight PFSs are also useful materials for a range of applications including LbL self‐assembly in highly confined spaces.
Reinforced Self‐Assembly of Hexa‐peri‐hexabenzocoronenes by Hydrogen Bonds: From Microscopic Aggregates to Macroscopic Fluorescent Organogels
Authors: Dou Xi , Pisula Wojciech , Wu Jishan , Bodwell Graham J. , Müllen Klaus 
Published: October 2007

AbstractHexa‐peri‐hexabenzocoronene derivatives (HBCs) that have hydrogen‐bonding functionalities (either amido or ureido groups) adjacent to the aromatic cores have been synthesized to study the effects of intracolumnar hydrogen bonds on the self‐assembly behavior of HBCs. The hydrogen bonds effectively increased the aggregation tendency of these compounds in solution. In the bulk state, the typical columnar supramolecular arrangement of HBCs was either stabilized substantially (1 a, 1 b, 2 a, and 2 b), or suppressed by dominant hydrogen‐bonding interactions (3). For some of the compounds (1 a, 2 a, and 2 b), the supramolecular arrangement adopted in the liquid‐crystalline state was even retained after annealing, presumably owing to the reinforcement of the π‐stacking interactions by the hydrogen bonds. Additionally, the combined effect of the hydrogen bonds and π‐stacking of the aromatic moieties led to the formation of fluorescent organogels, whereby some derivatives were further investigated as novel low molecular‐mass organic gelators (LMOGs).
Synthesis of 4‐Aminotropones from [(Sulfinyl or Sulfonyl)methyl]‐Substituted p‐Quinamines
Authors: Carreño M. Carmen , Ortega‐Guerra Montserrat , Ribagorda María , Sanz‐Cuesta M. Jesús 
Published: October 2007

AbstractAn efficient synthesis of 4‐aminotropones has been achieved in excellent yields by simple treatment of 4‐amino‐4‐[(p‐tolylsulfinyl)methyl]‐2,5‐cyclohexadienones (p‐quinamines) with NaH. The method allowed regiocontrolled access to 3‐methyl, 5‐methyl‐ and 3,5‐dimethyl‐substituted derivatives starting from p‐quinamines with adequate substituents at the cyclohexadienone moiety and/or at the carbon linked to the sulfur function. The p‐quinamines in turn were easily accessible from N‐Boc p‐anisidines (Boc=tert‐butoxycarbonyl) by electrochemical oxidation in MeOH to quinone imine monoketals, followed by addition of a α‐lithium sulfinyl carbanion to the imino group, and ketal hydrolysis. Oxidation of the sulfoxide gave the sulfonyl‐substituted p‐quinamines that, upon basic treatment, behave similarly. The p‐quinamine 55 and bis‐p‐quinamine 56, resulting in the addition of the anion derived from dimethyl sulfone to the p‐quinonimine ketal 14, also gave the 4‐aminotropone. The mechanism involves the initial formation of a α‐sulfonyl carbanion, which intramolecularly attacks the cyclohexadienone giving a norcaradiene‐like enolate intermediate, the evolution of which through a ring‐expansion process, pushes off a methyl sulfinate anion or SO2. This efficient process fulfils the criteria of atom economy. The introduction of a proline substituent in the nitrogen of the starting p‐quinamine allowed the synthesis of an enantiopure 4‐aminotropone, the asymmetric Diels–Alder reactions of which with maleimide occurred in a highly endo and π‐facial diastereoselective manner.
The use of circular dichroism spectroscopy for studying the chiral molecular self‐assembly: An overview
Authors: Gottarelli Giovanni , Lena Stefano , Masiero Stefano , Pieraccini Silvia , Spada Gian Piero 
Published: October 2007

AbstractSelf‐assembly plays an important role in the formation of many chiral biological structures and in the preparation of chiral functional materials. Therefore the control of chirality in synthetic or biological self‐assembled systems is important either for the comprehension of recognition phenomena or to obtain materials with predictable and controllable properties. Circular dichroism was developed to study molecular chirality, however, because of its outstanding sensitivity to chiral perturbations of the system under investigation; it has been extended more recently to supramolecular chemistry. In particular, self‐assembly processes leading to the formation of chiral supramolecular architectures (and eventually to gels or liquid crystal phases) can be monitored by CD. Furthermore, CD spectroscopy often allows one to obtain structural information on the assembled structures. This review deals with representative contributions to the study of supramolecular chirality by means of circular dichroism. Chirality, 2008. © 2007 Wiley‐Liss, Inc.
The use of X‐ray crystallography to determine absolute configuration
Authors: Flack H. D. , Bernardinelli G. 
Published: October 2007

AbstractEssential background on the determination of absolute configuration by way of single‐crystal X‐ray diffraction (XRD) is presented. The use and limitations of an internal chiral reference are described. The physical model underlying the Flack parameter is explained. Absolute structure and absolute configuration are defined and their similarities and differences are highlighted. The necessary conditions on the Flack parameter for satisfactory absolute‐structure determination are detailed. The symmetry and purity conditions for absolute‐configuration determination are discussed. The physical basis of resonant scattering is briefly presented and the insights obtained from a complete derivation of a Bijvoet intensity ratio by way of the mean‐square Friedel difference are exposed. The requirements on least‐squares refinement are emphasized. The topics of right‐handed axes, XRD intensity measurement, software, crystal‐structure evaluation, errors in crystal structures, and compatibility of data in their relation to absolute‐configuration determination are described. Characterization of the compounds and crystals by the physicochemical measurement of optical rotation, CD spectra, and enantioselective chromatography are presented. Some simple and some complex examples of absolute‐configuration determination using combined XRD and CD measurements, using XRD and enantioselective chromatography, and in multiply‐twinned crystals clarify the technique. The review concludes with comments on absolute‐configuration determination from light‐atom structures. Chirality, 2008. © 2007 Wiley‐Liss, Inc.
Why is it important to simultaneously use more than one chiroptical spectroscopic method for determining the structures of chiral molecules?
Authors: Polavarapu Prasad L. 
Published: October 2007

AbstractIn recent years, four different chiroptical spectroscopic methods, namely vibrational circular dichroism, vibrational Raman optical activity, electronic circular dichroism, and optical rotatory dispersion, have become popular for establishing the absolute configuration and predominant conformations of chiral molecules in solution state. Many individual laboratories normally utilize only one of these methods to derive the molecular structural information. Although that approach may be satisfactory for most of the molecules studied, it is to be noted that in some instances a single method can give ambiguous conclusions or may not give complete structural information. This article summarizes the situations where simultaneous use of more than one chiroptical spectroscopic method is required to obtain molecular structural information and recommends the routine application of more than one chiroptical spectroscopic method for any given molecule. Chirality, 2008. © 2007 Wiley‐Liss, Inc.
Absolute configuration of tropane alkaloids bearing two α,β‐unsaturated ester functions using electronic CD spectroscopy: Application to (R,R)‐trans‐3‐hydroxysenecioyloxy‐6‐senecioyloxytropane
Authors: Humam Munir , Christen Philippe , Muñoz Orlando , Hostettmann Kurt , Jeannerat Damien 
Published: October 2007

AbstractThe absolute configuration of heterocyclic natural products substituted with two mobile α,β‐unsaturated esters was studied using electronic circular dichroism (CD) spectroscopy. The conformational flexibility of the side chains imposed the use of density functional theory calculation to determine the set of the most probable conformations in solution. The electronic CD and UV spectra were calculated by Boltzmann‐weighted average of the simulated spectra using the results of the excited states calculation of a set of simplified structures. Comparison with the experimental CD spectrum allowed to determine whether the calculations were made with the right enantiomer. The method was applied to the determination of the absolute configuration of (R,R)‐trans‐3‐hydroxysenecioyloxy‐6‐senecioyloxytropane. Chirality, 2007. © 2007 Wiley‐Liss, Inc.