bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis of Chiral 2‐Hydroxy‐1‐methylpropanoates by Rhodium‐Catalyzed Stereoselective Hydrogenation of α‐(Hydroxymethyl)‐acrylate Derivatives
Authors: Holz Jens , Schäffner Benjamin , Zayas Odalys , Spannenberg Anke , Börner Armin
Published: November 2008

The synthesis of chiral 3‐hydroxy‐2‐methylpropanoic acid esters (e.g., “Roche ester” 3a) based on the rhodium‐catalyzed stereoselective hydrogenation of Baylis–Hillman reaction products was investigated. Full conversions and enantioselectivities of up to 99% at a substrate/catalyst ratio of up to 500/1 were achieved by application of bisphospholanes of the catASium M series as ancillary ligands. An interesting kinetic resolution was observed by the diastereoselective hydroxy‐directed hydrogenation of related racemic β‐branched precursors affording mainly anti‐isomers with up to 96%ee.
A Novel Enantioselective Catalytic Tandem Oxa‐Michael–Henry Reaction: One‐Pot Organocatalytic Asymmetric Synthesis of 3‐Nitro‐2H‐chromenes
Authors: Xu Dan‐Qian , Wang Yi‐Feng , Luo Shu‐Ping , Zhang Shuai , Zhong Ai‐Guo , Chen Hui , Xu Zhen‐Yuan
Published: November 2008

An enantioselective oxa‐Michael–Henry reaction of substituted salicylaldehydes with nitroolefins that proceeds though an aromatic iminium activation (AIA) has been developed by using a chiral secondary amine organocatalyst and salicylic acid as a co‐catalyst. The corresponding 3‐nitro‐2H‐chromenes were obtained in moderate‐to‐good yields with up to 91%eeunder mild conditions. Based on the experimental results and ESI‐mass spectrometric detection of the intermediates, a plausible transition state has been proposed to explain the origin of the activation and the asymmetric induction.
Heck Cross‐Coupling of Aryldiazonium Tetrafluoroborate with Acrylates Catalyzed by Palladium on Charcoal
Authors: Felpin François‐Xavier , Fouquet Eric , Zakri Cécile
Published: November 2008

A property‐activity relationship study of various palladium supported on charcoal (Pd/C) catalysts has been undertaken for the Heck reaction of aryldiazonium tetrafluoroborate with acrylates. The optimized protocol enables the cross‐coupling with a low loading of palladium at room temperature in technical grade methanol. Although the catalyst could not be recycled at this time, measurement of the palladium content by inductively coupled plasma mass spectrometry (ICP‐MS) shows low palladium contamination of the solvent and product, rendering this method safer for the environment compared to homogeneous conditions.
The transition to post‐industrial BMI values among US children
Authors: Komlos John , Breitfelder Ariane , Sunder Marco
Published: November 2008

The trend in the BMI values of US children has not been estimated very convincingly because of the absence of longitudinal data. Our objective is to estimate time series of BMI values by birth cohorts instead of measurement years. We use five regression models to estimate the BMI trends of non‐Hispanic US‐born black and white children and adolescents ages 2–19 between 1941 and 2004. The increase in BMIZ values during the period considered was 1.3σ (95% CI: 1.16σ; 1.44σ) among black girls, 0.8σ for black boys, 0.7σ for white boys, and 0.6σ for white girls. This translates into an increase in BMI values of some 5.6, 3.3, 2.4, and 1.5 units, respectively. While the increase in BMI values started among the birth cohorts of the 1940s among black girls, the rate of increase tended to accelerate among all four ethnic/gender groups born in the mid‐1950s to early‐1960s. Some regional evidence leads to the conjecture that the spread of automobiles and radios affected the BMI values of boys already in the interwar period. We suppose that the changes in lifestyle associated with the labor saving technological developments of the 20th century are associated with the weight gains observed. The increased popularity of television viewing was most prominently associated with the contemporaneous acceleration in BMI gain. Am. J. Hum. Biol., 2009. © 2008 Wiley‐Liss, Inc.
Constructing a fair, efficient, and cost‐effective arbitration
Authors: Claiborne Zela G.
Published: November 2008

Following up on last month's skills article by Stradley Ronon attorneys on establishing a framework for resolving disputes in arbitration, Zela G. Claiborne, of San Francisco, describes additional sophisticated strategic moves for advocates and parties
Getting to the table, kicking and screaming: Drafting an enforceable mediation provision
Authors: Katz Lucy V.
Published: November 2008

In the first of two parts, Lucy V. Katz, of Fairfield, Conn., lays out the current law on deal‐time mediation provisions, ahead of next month's state‐of‐the‐art sample clause
New securities ADR pilot launches, allowing industry arbitrator removal
Authors: Bleemer Russ
Published: November 2008

The securities markets' regulatory arm got a good response last month as it opened a pilot program directed at addressing public and Congressional concerns over the role and influence of so‐called nonpublic arbitrators— the industry representatives who have been mainstays of the industry's arbitration processes for decades
Synthese von 11C‐, 18F‐, 15O‐ und 13N‐Radiotracern für die Positronenemissionstomographie
Authors: Miller Philip W. , Long Nicholas J. , Vilar Ramon , Gee Antony D.
Published: November 2008

Die Positronenemissionstomographie (PET) ist eine leistungsfähige Bildgebungsmethode, die zur Untersuchung und Visualisierung der menschlichen Physiologie eingesetzt wird. Das Funktionsprinzip der PET beruht auf der Detektion positronenemittierender Radiopharmazeutika. Aus PET‐Experimenten können direkte Informationen über Stoffwechselvorgänge, Rezeptor‐Enzym‐Funktionen und biochemische Mechanismen im lebenden Gewebe erhalten werden. Anders als die Magnetresonanztomographie (MRT) und die Computertomographie (CT), die in erster Linie anatomische Bilder liefern, kann die PET chemische Veränderungen messen, die bereits vor dem Auftreten anatomischer Krankheitszeichen auftreten. Die PET ist dabei, sich als eine revolutionäre Methode für die Diagnostik von Körperfunktionen zu etablieren, die die Anwendung individueller, auf den Patienten zugeschnittener Behandlungsmethoden ermöglicht. Allerdings ist die Entwicklung von Synthesestrategien für neuartige positronenemittierende Moleküle nicht trivial. In diesem Aufsatz diskutieren wir die entscheidenden Aspekte bei der Synthese von PET‐Radiotracern mit den kurzlebigen Positronenemittern 11C, 18F, 15O und 13N. Der Schwerpunkt liegt auf den jüngsten Fortschritten bei der Entwicklung von Radiomarkierungsstrategien. Wir hoffen, dass dieser Aufsatz das Interesse von Synthesechemikern auch außerhalb der Radiochemie finden wird und die Bedeutung der PET in der molekularen Bildgebung sowie den Bedarf an neuen, innovativen chemischen Strategien für verbesserte Radiomarkierungstechniken aufzeigt.
Cloning of the dog bile salt export pump (BSEP; ABCB11) and functional comparison with the human and rat proteins
Authors: Yabuuchi Hikaru , Tanaka Kenji , Maeda Miyako , Takemura Masaaki , Oka Masaki , Ohashi Rikiya , Tamai Ikumi
Published: November 2008

The dog bile salt export pump (BSEP; ABCB11) was cloned and expressed in a Sf9 insect cell system. The deduced amino acid sequence encodes a 1325‐amino‐acid protein, which shows 89.4% and 80.2% homology with human BSEP and rat Bsep, respectively. The transcript of the dog Bsep gene was detected at a high level in liver, but not other tissues, by quantitative RT‐PCR. The BSEP‐expressing membrane vesicles isolated from Sf9 cells exhibited saturable uptake of [3H]taurocholic acid with Michaelis constants (Km) of 33.7, 22.2 and 19.9 µM for the dog, rat and human transporters, respectively. The uptake of [3H]taurocholic acid by all three transporters was significantly inhibited by troglitazone, glibenclamide, and other several inhibitors, while pravastatin inhibited dog Bsep and human BSEP, but not rat Bsep at 100 µM. The IC50 of troglitazone for dog Bsep, human BSEP, and rat Bsep were 32, 20, and 60 µM, and those of pravastatin were 441, 240 and >1,000 µM, respectively. In conclusion, while dog Bsep shows similar ATP‐dependent bile acid transport characteristics to human BSEP and rat Bsep, there is a species difference in affinity for drugs such as pravastatin and troglitazone. Copyright © 2008 John Wiley & Sons, Ltd.
Prevalence of spina bifida among children and adolescents in metropolitan Atlanta
Authors: Shin Mikyong , Besser Lilah M. , Correa Adolfo
Published: November 2008

BACKGROUND:Although studies have examined the prevalence of spina bifida (SB) among births, little is known about the SB prevalence among children and adolescents. We estimated the prevalence of SB among children and adolescents in metropolitan Atlanta.METHODS:This study used data from a population‐based registry of birth defects, with information on children with SB (cases) born in five Atlanta counties from 1979–2002. The population at risk was derived from United States Census data and variations in SB prevalence were examined by race/ethnicity, sex, lesion level, age group under 20 years, 4‐year birth cohort, and time period using Poisson regression.RESULTS:From 1979 to 2002, SB birth prevalence decreased from 6.3 to 3.2 per 10,000 live births (p< 0.001) and SB prevalence within each age group also declined. In 2002, there were 211 children 0–19 years old surviving with SB in Atlanta (2.4 per 10,000 children 0–19 years old); prevalence of SB was higher among non‐Hispanic whites and among children with lumbosacral lesion but did not vary by sex. With the exception of the most recent birth cohort (1998–2002), within each 4‐year birth cohort, the prevalence of SB was generally higher among non‐Hispanic whites than among non‐Hispanic blacks.CONCLUSIONS:This study provides minimum prevalence estimates among children and adolescents with SB in metropolitan Atlanta, and identifies race/ethnic disparities in such prevalence estimates. This information could be useful for assessing the specialized health care needs for children with SB and the possible reasons for the racial/ethnic variation in prevalence of SB. Birth Defects Research (Part A), 2008. © 2008 Wiley‐Liss, Inc.
Synthesis of DNA Strands Site‐Specifically Damaged by C8‐Arylamine Purine Adducts and Effects on Various DNA Polymerases
Authors: Böge Nicolas , Jacobsen Maike I. , Szombati Zita , Baerns Sabrina , Di Pasquale Francesca , Marx Andreas , Meier Chris
Published: November 2008

C8‐Arylamine‐dG and C8‐arylamine‐dA adducts have been prepared using palladium cross‐coupling chemistry. These adducts were subsequently converted into the corresponding 5′‐O‐DMTr‐C8‐arylamine‐3′‐O‐phosphoramidites and then used for the automated synthesis of different site‐specifically modified oligonucleotides. These “damaged” oligonucleotides have been characterized by ESI‐MS, UV thermal stability assays, and circular dichroism, and they have been used in EcoRI assays as well as in primer extension studies using various DNA polymerases.
Supramolecular Chirality and Reversible Chiroptical Switching in New Chiral Liquid‐Crystal Azopolymers
Authors: Barberá Joaquín , Giorgini Loris , Paris Fabio , Salatelli Elisabetta , Tejedor Rosa M. , Angiolini Luigi
Published: November 2008

The synthesis of chiral liquid‐crystalline polymers of well‐controlled structure (linear and three‐armed star‐shaped) with distinct average chain lengths and low polydispersity was achieved by atom transfer radical polymerisation (ATRP) of a new optically active monomer (S)‐4‐[6‐(2‐methacryloyloxypropanoyloxy)hexyloxy)]‐4′‐ethoxyazobenzene [(S)‐ML6A], containing the L‐lactic residue of one absolute configuration in the side‐chain. All the obtained polymeric samples, characterised by differential scanning calorimetry (DSC), X‐ray diffraction (XRD) and polarised optical microscopy (POM), exhibit a smectic A1/2 (fully interdigitated) liquid‐crystalline phase and high cleaning points, with transition temperatures dependent on the average polymerisation degree and the macromolecular structure. The chirality originated at the molecular level by the asymmetric functionality of the L‐lactic acid residue provides the polymers, in the smectic phase, of highly homogeneous conformations with a prevailing chirality related to the presence of H‐aggregates having conformational dissymmetry of one prevailing screw‐sense. By irradiating with circularly polarised light (CPL), it is possible to photomodulate the chiroptical properties of these intrinsically chiral polymeric thin films. Upon irradiation with left‐handed CPL (l‐CPL), the circular dichroism (CD) spectra of the films show enhancement of ellipticity and a net inversion of sign. The effect is reversible and the mirror image of the CD spectrum can be restored by pumping with right‐handed CPL radiation (r‐CPL). The results show the ability of l‐CPL to invert the supramolecular chirality of the materials and demonstrate the essential role of azoaromatic aggregates.
Adopting helical CT screening for lung cancer
Authors: McMahon Pamela M. , Kong Chung Yin , Weinstein Milton C. , Tramontano Angela C. , Cipriano Lauren E. , Johnson Bruce E. , Weeks Jane C. , Gazelle G. Scott
Published: November 2008

BACKGROUND.

Simulation modeling can synthesize data from single‐arm studies of lung cancer screening and tumor registries to investigate computed tomography (CT) screening. This study estimated changes in lung cancer outcomes through 2005, had chest CT screening been introduced in 1990.

METHODS.

Hypothetical individuals with smoking histories representative of 6 US cohorts (white males and females aged 50, 60, and 70 years in 1990) were simulated in the Lung Cancer Policy Model, a comprehensive patient‐level simulation model of lung cancer development, screening, and treatment. A no screening scenario corresponded to observed outcomes. We simulated 3 screening scenarios in current or former smokers with ≥20 pack‐years as follows: 1‐time screen in 1990; and annual, and twice‐annually screenings beginning in 1990 and ending in 2005. Main outcomes were days of life between 1990 and 2005 and life expectancy in 1990 (estimated by simulating life histories past 2005).

RESULTS.

All screening scenarios yielded reductions (compared with no screening) in lung cancer‐specific mortality by 2005, with larger reductions predicted for more frequent screening. Compared with no screening, annual screening of ever‐smokers with at least 20 pack‐years of cigarette exposure provided ever‐smokers with an additional 11 to 33 days of life by 2005, or an additional 3‐10 weeks of (undiscounted) life expectancy. In sensitivity analyses, the largest effects on gains from annual screening were due to reductions in screening adherence and increased smoking cessation.

CONCLUSIONS.

The adoption of CT screening, had it been available in 1990, might have resulted in a modest gain in life expectancy. Cancer 2008. © 2008 American Cancer Society.
p73 G4C14‐to‐A4T14 polymorphism and risk of human papillomavirus‐associated squamous cell carcinoma of the oropharynx in never smokers and never drinkers
Authors: Chen Xingming , Sturgis Erich M. , Etzel Carol J. , Wei Qingyi , Li Guojun
Published: November 2008

BACKGROUND.

The p53 tumor suppressor protein homolog p73 can be inactivated by oncoprotein E6 of human papillomavirus (HPV). Variation in p73 may alter the interaction between the E6 protein and p73 and, thus, alter the risk for HPV‐associated carcinogenesis. It is believed that the p73 G4C14‐to‐A4T14 polymorphism affects p73 function by altering gene expression; however, whether that polymorphism also alters the risk of HPV type 16 (HPV‐16)‐associated squamous cell carcinoma of the oropharynx (SCCOP) is unknown.

METHODS.

The current case‐control study included a case group of 188 non‐Hispanic white patients with newly diagnosed SCCOP and a control group of 349 healthy individuals. Logistic regression analyses were used to calculate odds ratios (ORs) and 95% confidence intervals (CIs) for cases and controls stratified by p73 genotype, age, sex, smoking status, alcohol use, and HPV‐16 status. The effects of p73 genotypes on the risk of HPV‐16‐associated SCCOP were explored with further stratification by smoking and drinking status.

RESULTS.

HPV‐16 seropositivity was associated with an increased risk of SCCOP (adjusted OR, 5.98; 95% CI, 3.89‐9.20), especially among never smokers (adjusted OR, 13.8; 95% CI, 5.91‐32.1), never drinkers (adjusted OR, 14.9; 95% CI, 5.24‐42.4), and individuals with p73 variant genotypes (GC/AT and AT/AT; adjusted OR, 7.96; 95% CI, 3.83‐16.5). Moreover, the risk of HPV‐16‐associated SCCOP for individuals who had p73 variant genotypes was particularly high in never smokers and never drinkers.

CONCLUSIONS.

The p73 G4C14‐to‐A4T14 polymorphism may modulate the risk of HPV‐16‐associated SCCOP, and the p73 variant genotypes may be markers of genetic susceptibility to HPV‐16‐associated SCCOP, particularly in never smokers and never drinkers. Cancer 2008. © 2008 American Cancer Society.
Cytogenetic abnormalities in a series of 1029 patients with primary myelodysplastic syndromes
Authors: Pozdnyakova Olga , Miron Patricia M. , Tang Guilin , Walter Otto , Raza Azra , Woda Bruce , Wang Sa A.
Published: November 2008

BACKGROUND.

Conventional karyotype has an established role in myelodysplastic syndrome (MDS) and is included in the International Prognostic Scoring System (IPSS) for patient risk stratification and treatment selection. Although some chromosomal abnormalities have been well characterized, the significance of several miscellaneous, infrequent, single chromosomal abnormalities remains to be defined. In addition, the emerging therapeutic agents may change the natural course of disease in patients with MDS and the cytogenetic impact on risk stratification.

METHODS.

Clinicopathologic data were retrieved on 1029 patients who had a diagnosis of primary MDS and had available cytogenetic data (karyotype) on file.

RESULTS.

Cytogenetic abnormalities were identified in 458 patients (45%) and occurred most frequently in patients who had refractory anemia with excess blasts (62%). Overall, the 3 cytogenetic risk groups defined by the IPSS—good, intermediate, and poor—effectively stratified the patients' overall survival (OS) (64 months, 31 months, and 12 months, respectively; P < .001). With the exception of gain of chromosome 8, single cytogenetic abnormalities within the intermediate group were extremely infrequent in the series but demonstrated variable OS ranging from 10 months for patients who had isochromosome (17q) to 69 months for patients who had deletion of 12p [del(12p)], suggesting different prognostic significance. In the poor cytogenetic risk group, patients with isolated del(7q) and derivative (1;7)(q10;p10) had a significantly better median OS than patients who had either loss of chromosome 7 or a complex karyotype (P < .05).

CONCLUSIONS.

The current data generated from a large cohort of patients with primary MDS indicated that some specific cytogenetic abnormalities carry different risk than their IPSS cytogenetic risk‐group assignment, especially in the new treatment era. Because of the extreme low frequency, additional combined studies are needed to better categorize some rare single cytogenetic abnormalities within the intermediate cytogenetic risk group. Cancer 2008. © 2008 American Cancer Society.
Larger tonic pupil size in young children with autism spectrum disorder
Authors: Anderson Christa J. , Colombo John
Published: November 2008

The symptoms of Autism Spectrum Disorder (ASD) have been suggested to manifest from atypical functioning of the autonomic nervous system (ANS), leading to altered arousal and atypical processing of salient stimuli. Coherent with this, persons with ASD show heightened autonomic activity, sleep difficulties, and structural and neurochemical alterations within the ANS. Recently, we observed decreased pupil responses to human faces in children with ASD. In the current study, we found differences in baseline (tonic) pupil size, with the ASD group exhibiting a larger pupil size than age‐matched controls. Pupil responses are sensitive and reliable measures of ANS functioning, thus, this finding highlights the role of the ANS, and may provide clues about underlying neuropathology. © 2008 Wiley Periodicals, Inc. Dev Psychobiol 51: 207–211, 2009
Expression of Islet1 in thyroid development related to budding, migration, and fusion of primordia
Authors: Westerlund Jessica , Andersson Louise , Carlsson Therese , Zoppoli Pietro , Fagman Henrik , Nilsson Mikael
Published: November 2008

The LIM homeodomain transcription factor Isl1 was investigated in mouse thyroid organogenesis. All progenitor cells of the midline thyroid diverticulum and lateral primordia (ultimobranchial bodies) expressed Isl1. This pattern persisted until the growing anlagen fused at embryonic day (E) 13.5. In Isl1 null mutants thyroid progenitors expressing Nkx2.1 and Pax8 were readily specified in the anterior endoderm but the size of the thyroid rudiment was reduced. In late development, only immature C‐cells expressed Isl1. In the adult gland the number of Isl1+ cells was small compared with cells expressing calcitonin. Analysis of microarray profiles indicated a higher level of Isl1 expression in medullary thyroid carcinomas than in tumors derived from follicular cells. Together, these findings suggest that Isl1 may be a novel regulator of thyroid development before terminal differentiation of the endocrine cell types. Isl1 is an embryonic C‐cell precursor marker that may be relevant also in cancer developed from the mature C‐cell. Developmental Dynamics 237:3820–3829, 2008. © 2008 Wiley‐Liss, Inc.
Epigenome and chromatin structure in human embryonic stem cells undergoing differentiation
Authors: Bártová Eva , Galiová Gabriela , Krejčí Jana , Harničarová Andrea , Strašák Luděk , Kozubek Stanislav
Published: November 2008

Epigenetic histone (H3) modification patterns and the nuclear radial arrangement of select genetic elements were compared in human embryonic stem cells (hESCs) before and after differentiation. H3K9 acetylation, H3K9 trimethylation, and H3K79 monomethylation were reduced at the nuclear periphery of differentiated hESCs. Differentiation coincided with centromere redistribution, as evidenced by perinucleolar accumulation of the centromeric markers CENP‐A and H3K9me3, central repositioning of centromeres 1, 5, 19, and rearrangement of other centromeres at the nuclear periphery. The radial positions of PML, RARα genes, and human chromosomes 10, 12, 15, 17, and 19 remained relatively stable as hESCs differentiated. However, the female inactive H3K27‐trimethylated X chromosome occupied a more peripheral nuclear position in differentiated cells. Thus, pluripotent and differentiated hESCs have distinct nuclear patterns of heterochromatic structures (centromeres and inactive X chromosome) and epigenetic marks (H3K9me3, and H3K27me3), while relatively conserved gene density‐related radial chromatin distributions are already largely established in undifferentiated hES cells. Developmental Dynamics 237:3690–3702, 2008. © 2008 Wiley‐Liss, Inc.
Requirement for a core 1 galactosyltransferase in the Drosophila nervous system
Authors: Lin Yuh‐Ru , Reddy B.V.V.G. , Irvine Kenneth D.
Published: November 2008

Mucin type O‐glycosylation is a widespread modification of eukaryotic proteins, but its functional requirements remain incompletely understood. It is initiated by the attachment of N‐acetylgalactosamine (GalNAc) to Ser or Thr residues, and then elongated by additional sugars. We have examined requirements for mucin‐type glycosylation in Drosophila by characterizing the expression and phenotypes of core 1 galactosyltransferases (core 1 GalTs), which elongate O‐GalNAc by adding galactose in a β1,3 linkage. Drosophila encode several putative core 1 GalTs, each expressed in distinct patterns. CG9520 (C1GalTA) is expressed in the amnioserosa and central nervous system. A null mutation in C1GalTA is lethal, and mutant animals exhibit a striking morphogenetic defect in which the ventral nerve cord is greatly elongated and the brain hemispheres are misshapen. Lectin staining and blotting experiments confirmed that C1GalTA contributes to the synthesis of Gal‐β1,3‐GalNAc in vivo. Our results identify a role for mucin‐type O‐glycosylation during neural development in Drosophila. Developmental Dynamics 237:3703–3714, 2008. © 2008 Wiley‐Liss, Inc.
Thermal and Catalytic Dehydrogenation of the Guanidine–Borane Adducts H3B·hppH (hppH = 1,3,4,6,7,8‐hexahydro‐2H‐pyrimido[1,2‐a]pyrimidine) and H3B·N(H)C(NMe2)2: A Combined Experimental and Quantum Chemical Study
Authors: Ciobanu Oxana , Allouti Fayçal , Roquette Pascal , Leingang Simone , Enders Markus , Wadepohl Hubert , Himmel Hans‐Jörg
Published: November 2008

Herein thermal and catalytic dehydrogenation of the guanidine–borane adducts H3B·hppH (hppH = 1,3,4,6,7,8‐hexahydro‐2H‐pyrimido[1,2‐a]pyrimidine) and H3B·N(H)C(NMe2)2 are analysed. Thermal decomposition of H3B·hppH at 80 °C leads to [HB(μ‐hpp)]2 and a second boron hydride, which is tentatively identified as [(κ2N‐hpp)BH2]. Decomposition in boiling toluene (110 °C) leads to a mixture of [H2B(μ‐hpp)]2 and [HB(μ‐hpp)]2, from which [H2B(μ‐hpp)]2 can be separated and crystallised. In the presence of a catalyst (with Cp2TiCl2/nBuLi or [Rh(1,5‐cod)Cl]2 as precatalysts) dehydrogenation at 80 °C leads predominantly to [H2B(μ‐hpp)]2. In the case of H3B·N(H)C(NMe2)2 uncatalysed dehydrogenation turns out to be a very slow process even at 110 °C. Interestingly, the ultimate product of this process is oligomeric methylimino borane, [HBNMe]n. This pathway can be modelled and understood with the aid of quantum chemical calculations. Faster dehydrogenation can be initiated by addition of a catalyst. Finally, the possible mechanisms for thermal and Cp2Ti‐catalysed dehydrogenation are analysed for the model compound H3B·N(H)C(NH2)2 by means of quantum chemical (DFT) calculations.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Reactions of (Me2C)(Me2Si)[(η5‐C5H3)­Mo(CO)3]2 with Phosphanylalkynes: Rearrangement of Phosphanylalkynes into Phosphido‐Substituted Vinylidenyl Ligands by Cleavage of the P–C(alkyne) Bond and Formation of a P–C(alkene) Bond
Authors: Li Bin , Xu Shansheng , Song Haibin , Wang Baiquan
Published: November 2008

This article deals with the thermal reactions of the doubly bridged bis(cyclopentadienyl) dinuclear molybdenum complex (Me2C)(Me2Si)[(η5‐C5H3)Mo(CO)3]2 (1) with a series of phosphanylalkynes PhnP(C≡CR)3–n (n = 2, 1, 0; R = Ph, Fc). In addition to the complex (Me2C)(Me2Si)[(η5‐C5H3)2Mo2(CO)4(μ‐η2‐η2(⟂)‐R1C≡CR2)] [R1 = Ph, R2 = Ph2P, 2; R1 = Ph, R2 = Ph2P(O), 4; R1 = Ph, R2 = PhP(C≡CPh), 6; R1 = Fc, R2 = PhP(C≡CFc), 8; and R1 = Fc, R2 = PhP(O)(C≡CFc), 10], in which the phosphanylalkynes acted as disubstituted acetylenes, the P–C(alkyne) bond cleavage and phosphanylalkyne rearrangement products (Me2C)(Me2Si)[(η5‐C5H3)2Mo2(CO)4{μ‐η1‐η2‐C=C(R1)R2}] [R1 = Ph, R2 = Ph2P, 3; R1 = Fc, R2 = Ph2P, 5; R1 = Ph, R2 = PhP(C≡CPh), 7; and R1 = Fc, R2 = PhP(C≡CPh), 9] were also isolated when mono‐ and bis(ethynyl)‐functionalized phosphanes reacted with 1. Reactions of tris(ethynyl)‐functionalized phosphanes with 1 afforded the phosphanylalkyne‐bridged complexes (or/andtheir oxide) (Me2C)(Me2Si)[(η5‐C5H3)2Mo2(CO)4(μ‐η2‐η2(⟂)‐R1C≡CR2)] [R1 = Ph, R2 = P(C≡CPh)2, 11a and 11b; R1 = Ph, R2 = P(O)(C≡CPh)2, 12; and R1 = Fc, R2 = P(C≡CFc)2, 13]. All the new complexes were fully characterized. X‐ray characterization of 3, 5, 6, 7, 11a, 11b, 13, and P(C≡CFc)3 are also provided.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Novel Coordination Modes for E4S3 Cage Molecules (E = P, As) in Unprecedented Quaternary As4S3(CuCl)n (n = 1,2) Solid‐State Phases
Authors: Schwarz Patrick , Wachter Joachim , Zabel Manfred
Published: November 2008

First examples of the coordination chemistry of the As4S3 cage were obtained from solutions of As4S3·M(CO)5 (M = Cr, W) in CH2Cl2 and CuCln in CH3CN (n = 1) or CH3OH (n = 2) through interdiffusion techniques. The compounds (As4S3)(CuCl)n (1: n = 1; 2: n = 2) exhibit Cu coordination exclusively through the sulfur bridges. The crystal structure of 1 containsa saw‐like [CuCl] backbone to which As4S3 cages are alternately fixed on both sides through two of their sulfur atoms. The crystal structure of 2 is built up of sheets, in which As4S3 molecules are connected by folded four‐membered Cu2Cl2 rings through all sulfur atoms. Comparative Raman spectra of As4S3 and 1 indicate significant interactions between the cage S atoms and Cu.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
On the Importance of the Nature of Hydrogen Bond Donors in Multiple Hydrogen Bond Systems
Authors: Taubitz Jörg , Lüning Ulrich
Published: November 2008

Association constants for the reaction between a fourfold hydrogen bond receptor 4 possessing an AADA hydrogen bond pattern and several complementary partners 5–7 with DDAD and DDA patterns have been determined by NMR titration and by isothermal titration calorimetry (ITC). A variation of one donor site in the DDAD pattern resulted in the following, surprising sequence of stability of the complexes: KAss(6, X = NHCOR) > KAss(7, X = H) > KAss(5, X = NHR). The synthesis of a well soluble DDAD receptor, the amidopyridylurea 6b with a triethylene glycol chain, is described. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
The Silver Amalgam Film Electrode in Adsorptive Stripping Voltammetric Determination of Palladium(II) as Its Dimethyldioxime Complex
Authors: Bobrowski Andrzej , Gawlicki Marek , Kapturski Paweł , Mirceski Valentin , Spasovski Filip , Zarębski Jerzy
Published: November 2008

The paper features a description of a sensitive adsorptive stripping voltammetric protocol for the palladium(II) determination in the presence of dimethylglyoxime (DMG) at an amalgam film electrode (Hg(Ag)FE) of prolonged analytical applicability. The procedure is based on the adsorptive preconcentration of the Pd(II)‐dimethylglyoxime complex onto the (Hg(Ag)FE) at −0.45 V, followed by a negatively going square‐wave voltammetric scan. Factors affecting the stripping performance, such as the composition of the supporting electrolyte, including different ligands, DMG concentration, pH, potential and time of preconcentration, and SW frequency have been investigated and optimized. The optimized procedure yields favorable and highly stable stripping responses with good precision (RSD=3% for a Pd concentration of 2 μg/L), low detection limit (0.15 μg/L Pd(II)), and good linearity (from 1.0 μg/L up to 50 μg/L, R2=0.998) with a deposition time of 60 s. Possible interferences from coexisting ions and surface active substances were studied.
Electrocatalysis of 2‐Diethylaminoethanethiol at Nickel Nanoparticle‐Electrodecorated Single‐Walled Carbon Nanotube Platform: An Adsorption‐Controlled Electrode Process
Authors: Adekunle Abolanle S. , Pillay Jeseelan , Ozoemena Kenneth I.
Published: November 2008

Electrocatalytic behavior of diethylaminoethanethiol (DEAET) at nickel nanoparticle‐electrodecorated single‐walled carbon nanotube (SWCNT‐Ni) platform is presented. We demonstrate that the electrocatalytic response is governed by adsorption‐controlled kinetics and that adsorptive stripping voltammetry (AdsSV) represents a viable analytical voltammetry for the sensitive detection of this hydrolysis product of a V‐type nerve agent.
Mediatorless Hydrogen Peroxide Biosensor Based on Horseradish Peroxidase Immobilized on 4‐Carboxyphenyl Film Electrografted on Gold Electrode
Authors: Radi Abd‐Elgawad , Lates Vasilica , Marty Jean‐Louis
Published: November 2008

A novel method to fabricate a third‐generation hydrogen peroxide biosensor was reported. The electrode was first derivatized by electrochemical reduction of in situ generated 4‐carboxyphenyl diazonium salt (4‐CPDS) in acidic aqueous solution yielded stable 4‐carboxyphenyl (4‐CP) layer. The horseradish peroxidase (HRP) enzyme was then covalently immobilized by amidation between NH2 terminus of enzyme and COOH terminus of 4‐CP film making use of the carbodiimide chemistry. Electrodeposition conditions used to control electrode functionalization density and film electron transfer kinetics were assessed by chronoamperometry and electrochemical impedance spectroscopy. The immobilized HRP displayed excellent electrocatalytic activity towards the reduction of hydrogen peroxide (H2O2) without any mediators. The effect of various operational parameters was explored for optimum analytical performance. The reported biosensor exhibited fast amperometric response (within 5 s) to H2O2. The detection limit of the biosensor was 5 μM, and linear range was from 20 μM to 20 mM. Furthermore, the biosensor exhibited high sensitivity, good reproducibility, and long‐term stability.
Electrooxidation of Nitrite Mediated by Cu‐x‐Tetraaminophenylporphyrin (x=2, 3, and 4) Glassy Carbon‐Modified Electrodes: Effect of Substituent Position
Authors: Camargo Andrés , Aguirre María J. , Cheuquepán William , Chen Yo‐Ying , Ramírez Galo
Published: November 2008

A study of glassy carbon electrodes modified with poly‐Cu‐x‐tetraaminophenylporphyrin (TAPP) (x=2, 3, and 4) toward the electrooxidation of nitrite is reported. The position of the amino group influences the degree of electropolymerization and the response toward the electrooxidation of nitrite. The influence of pH on the electrocatalytic oxidation of nitrite was also studied, finding that the activity is strongly pH‐dependent. For each system (polymeric porphyrins, poly‐Cu‐2‐TAPP, poly‐Cu‐3‐TAPP, and poly‐Cu‐4‐TAPP), the behavior of the modified electrode as amperometric nitrite sensor was studied at the best pH response, finding a linear correlation over a wide range of concentrations for poly‐Cu‐3‐TAPP. With poly‐Cu‐2‐TAPP, the range is smaller, and there is no linear relationship for poly‐Cu‐4‐TAPP. The plot of Ip vs. the square root of the scan rate shows a linear relationship for all the polymer systems, indicating that the electrooxidation of nitrite in the modified electrodes is a process controlled by diffusion. The Tafel slope was calculated, indicating that the determining step in the electrooxidation of nitrite varies depending on the position of the substituent, showing a dramatic change in the nature of the active sites.
Homogeneous Platinum‐Deposited Screen‐Printed Edge Band Ultramicroelectrodes for Amperometric Sensing of Carbon Monoxide
Authors: Chou Chih‐Hung , Chang Jen‐Lin , Zen Jyh‐Myng
Published: November 2008

We report here the fabrication and application of an electrochemical carbon monoxide (CO) gas sensor based on the deposition of Pt nanoparticles on a screen‐printed edge band ultramicroelectrode (SPUME) with Nafion as the solid polymer electrolyte. Homogeneous size and distribution of Pt nanoparticles is stably deposited on the SPUME without either protective or capped agents. The edge diffusion effect at the SPUME, to even out the generation rate of hydrogen and to speed up the mass transfer of Pt solution, is believed to play a key role in achieving the deposition result. The obvious advantage of the proposed ultramicroelectrode system is that no supporting electrolyte (i.e., internal electrolyte) is required in the sensor scheme. The current–time curve recorded under conditions of +0.45 V vs. pseudo Ag reference electrode and various CO concentrations suggests that current response depends linearly on CO concentration up to 1000 ppm (correlation coefficient=0.994) with a sensitivity of 3.76 nA/(ppm⋅cm2). This report demonstrates potential application of the disposable CO gas sensor.
A compact high‐order HLL solver for nonlinear hyperbolic systems
Authors: Capdeville G.
Published: November 2008

We present a new finite‐volume method for calculating complex flows on non‐uniform meshes. This method is designed to be highly compact and to accurately capture all discontinuities that may arise within the solution of a nonlinear hyperbolic system.

In the first step, we devise a fourth‐degree Hermite polynomial to interpolate the solution. The coefficients defining this polynomial are calculated by using a least‐square method. To introduce monotonicity conditions within the procedure, two constraints are added into the least‐square system. Those constraints are derived by locally matching the high‐order Hermite polynomial with a low‐order TVD polynomial. To emulate these constraints only in regions of discontinuities, data‐depending weights are defined; these weights are based upon normalized indicators of smoothness of the solution and are parameterized by an O(1) quantity. The reconstruction so generated is highly compact and is fifth‐order accurate when the solution is smooth; this reconstruction becomes first order in regions of discontinuities.

In the second step, this reconstruction is inserted in an HLL approximate Riemann solver. This solver is designed to correctly capture all discontinuities that may arise into the solution. To this aim, we introduce the contribution of a possible contact discontinuity into the HLL Riemann solver.

Thus, a spatially fifth‐order non‐oscillatory method is generated. This method evolves in time the solution and its first derivative. In a one‐dimensional context, a linear spectral analysis and extensive numerical experiments make it possible to assess the robustness and the advantages of the method in computing multi‐scale problems with embedded discontinuities. Copyright © 2008 John Wiley & Sons, Ltd.
Modulation of human gingival fibroblast adhesion, morphology, tyrosine phosphorylation, and ERK 1/2 localization on polished, grooved and SLA substratum topographies
Authors: Kokubu Eitoyo , Hamilton Douglas W. , Inoue Takashi , Brunette Donald M.
Published: November 2008

Attachment of connective tissue to dental implants, which is influenced by surface topography, is an important determinant of implant success. Approaches employed to alter topography include acid etching or blasting to produce roughened surfaces, and production of precisely defined topographies using microfabrication techniques. The aim of this study was to assess the influence of polished, microgrooved, and sand‐blasted, large grit, acid‐etched (SLA) topographies on fibroblast adhesion, morphology, activation, and ERK 1/2 phosphorylation and localization. Human gingival fibroblasts (HGFs) spread on all tested surfaces within 2 h, and topography influenced the pattern of phosphotyrosine localization. Fibrillar adhesion formation was prominent in HGFs cultured on microgrooves and SLA at 24 h compared with smooth. No significant difference in ERK 1/2 phosphorylation was observed at 2 or 24 h, but nuclear localization depended on culture time and substratum topography. Nuclear localization of ERK 1/2 occurred at 2 h on polished surfaces, but was not evident at 1 week. In contrast, cells on SLA and grooved surfaces did not exhibit nuclear localization of ERK 1/2 at early times, but did at 1 week. The results of this study suggest that rough and microfabricated topographies influence fibroblast adhesion and intracellular signaling through focal adhesion/integrin‐dependent mechanisms in a time‐dependent manner. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Evaluation of the effect of four self‐etching adhesives ondentin permeability
Authors: Orucoglu Hasan , Belli Sema
Published: November 2008

Objective:

The aim of this study was to evaluate the effect of two two‐step and two single‐step self‐etching adhesives on dentin permeability using a computerized fluid filtration (CFF) test method.

Methodology:

Forty recently extracted sound human molar teeth were sectioned at the mid level of the crown to obtain dentin discs of 1 ± 0.2 mm. A total of 40 discs were obtained and randomly divided into four groups (n = 10). The permeability of the discs was measured using the CFF test method before and after application of the following self‐etching adhesives: Hybrid Bond, G‐Bond, AdheSE, and Protect Bond. Fluid movement measurements were made at 2‐min intervals for 8 min, and a mean of the values obtained was calculated for each specimen.

Results:

The in vitro fluid conductance of dentin discs treated with Hybrid Bond and AdheSE were lower than the dentin discs treated with G‐Bond and Protect Bond (p < 0.05).

Conclusion:

1‐Treating dentin discs with self‐etching adhesives caused significant reduction of dentin permeability. 2‐All self‐etching adhesives allowed diffusion of distilled water. However, AdheSE and Hybrid Bond showed the lowest permeability. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009
Predictive parameters for granulocyte colony‐stimulating factor‐induced peripheral blood stem cell mobilization
Authors: Okano Akira , Ashihara Eishi , Shimazaki Chihiro , Uchiyama Hitoji , Inaba Tohru , Taniguchi Kyoko , Maekawa Taira , Taniwaki Masafumi
Published: November 2008

To improve the selection of donors for allogeneic stem cell transplantation, it is important to identify reliable parameters that predict CD34+‐cell yields after granulocyte‐colony stimulating factor (G‐CSF)‐induced peripheral blood stem cell (PBSC) mobilization. We retrospectively investigated the peripheral blood (PB) kinetics of white blood cells (WBCs), CD34+ cells, matrix metalloproteinases (MMP)‐9 and ‐2, and tissue inhibitors of metalloproteinases (TIMP)‐1 and ‐2 in 15 healthy donors during their treatment with G‐CSF. All donors received 10 μg/kg of recombinant human G‐CSF once a day subcutaneously. Leukapheresis was initiated after 4 days of G‐CSF treatment, and G‐CSF treatment continued until the last day of leukapheresis. WBC and CD34+ cell numbers in the PB rose after 2 and 3 or 4 days of G‐CSF treatment, respectively. The PB CD34+ cell numbers on day 4 correlated weakly with the increase in WBC counts from day 1 to day 2 (R2 = 0.254, P = 0.056). There were also positive correlations between the CD34+ cell numbers in the PBSC products on day 4 and the CD34+ cells in the PB on days 1 and 4 (R2 = 0.768, P < 0.0001 and R2 = 0.816, P < 0.0005, respectively). The MMP‐9 plasma levels on days 1 and 4 also correlated positively with the day 4 circulating CD34+ cell numbers (R2 = 0.393, P < 0.05 and R2 = 0.406, P = 0.01, respectively). In conclusion, the CD34+ cell numbers in the PB steady state may be a useful parameter selecting allogeneic PBSC donors. J. Clin. Apheresis, 2008. © 2008 Wiley‐Liss, Inc.
Linear augmented Slater‐type orbital method for free standing clusters
Authors: Kang K. S. , Davenport J. W. , Glimm J. , Keyes D. E. , McGuigan M.
Published: November 2008

We have developed a Scalable Linear Augmented Slater‐Type Orbital (LASTO) method for electronic‐structure calculations on free‐standing atomic clusters. As with other linear methods we solve the Schrödinger equation using a mixed basis set consisting of numerical functions inside atom‐centered spheres and matched onto tail functions outside. The tail functions are Slater‐type orbitals, which are localized, exponentially decaying functions. To solve the Poisson equation between spheres, we use a finite difference method replacing the rapidly varying charge density inside the spheres with a smoothed density with the same multipole moments. We use multigrid techniques on the mesh, which yields the Coulomb potential on the spheres and in turn defines the potential inside via a Dirichlet problem. To solve the linear eigen‐problem, we use ScaLAPACK, a well‐developed package to solve large eigensystems with dense matrices. We have tested the method on small clusters of palladium. © 2008 Wiley Periodicals, Inc. J Comput Chem, 2009
Prediction and analysis of binding affinities for chemically diverse HIV‐1 PR inhibitors by the modified SAFE_p approach
Authors: Arenas Miguel , Villaverde M. Carmen , Sussman Fredy
Published: November 2008

One of the biggest challenges in the “in silico” screening of enzyme ligands is to have a protocol that could predict the ligand binding free energies. In our group we have developed a very simple screening function (referred to as solvent accessibility free energy of binding predictor, SAFE_p) which we have applied previously to the study of peptidic HIV‐1 protease (HIV‐1 PR) inhibitors and later to cyclic urea type HIV‐1 PR inhibitors. In this work, we have extended the SAFE_p protocol to a chemically diverse set of HIV‐1 PR inhibitors with binding constants that differ by several orders of magnitude. The resulting function is able to reproduce the ranking and in many cases the value of the inhibitor binding affinities for the HIV‐1 PR, with accuracy comparable with that of costlier protocols. We also demonstrate that the binding pocket SAFE_p analysis can contribute to the understanding of the physical forces that participate in ligand binding. The analysis tools afforded by our protocol have allowed us to identify an induced fit phenomena mediated by the inhibitor and have demonstrated that larger fragments do not necessarily contribute the most to the binding free energy, an outcome partially brought about by the substantial role the desolvation penalty plays in the energetics of binding. Finally, we have revisited the effect of the Asp dyad protonation state on the predicted binding affinities. © 2008 Wiley Periodicals, Inc. J Comput Chem, 2009
A combined semiempirical‐DFT study of oligomers within the finite‐chain approximation, evolution from oligomers to polymers
Authors: Derosa Pedro A.
Published: November 2008

A computationally cheap approach combining time‐independent density functional theory (TIDFT) and semiempirical methods with an appropriate extrapolation procedure is proposed to accurately estimate geometrical and electronic properties of conjugated polymers using just a small set of oligomers. The highest occupied molecular orbital–lowest unoccupied molecular orbital gap (HLG) obtained at a TIDFT level (B3PW91) for two polymers, trans‐polyacetylene ‐the simplest conjugated polymer, and a much larger poly(2‐methoxy‐5‐(2,9‐ethyl‐hexyloxy)‐1,4‐phenylenevinylene (MEH‐PPV) polymer converge to virtually the same asymptotic value than the excitation energy obtained with time‐dependent DFT (TDDFT) calculations using the same functional. For TIDFT geometries, the HLG is found to converge to a value within the experimentally accepted range for the band gap of these polymers, when an exponential extrapolation is used; however if semiempirical geometries are used, a linear fit of the HLG versus 1/n is found to produce the best results. Geometrical parameters are observed to reach a saturation value in good agreement with experimental information, within the length of oligomers calculated here and no extrapolation was considered necessary. Finally, the performance of three different semiempirical methods (AM1, PM3, and MNDO) and for the TIDFT calculations, the performance of 7 different full electron basis sets (6‐311+G**, 6‐31+ +G**, 6‐311+ +G**, 6‐31+G**, 6‐31G**, 6‐31+G*, and 6‐31G) is compared and it is determined that the choice of semiempirical method or the basis set does not significantly affect the results. © 2008 Wiley Periodicals, Inc. J Comput Chem 2009
Radiosynthesis of [18F]PBR111, a selective radioligand for imaging the translocator protein (18 kDa) with PET
Authors: Dollé Frédéric , Hinnen Françoise , Damont Annelaure , Kuhnast Bertrand , Fookes Christopher , Pham Tien , Tavitian Bertrand , Katsifis Andrew
Published: November 2008

PBR111 (2‐(6‐chloro‐2‐(4‐(3‐fluoropropoxy)phenyl)imidazo[1,2‐a]pyridin‐3‐yl)‐N,N‐diethylacetamide) is a novel, reported, high‐affinity and selective ligand for the translocator protein (18 kDa). PBR111 has been labelled with fluorine‐18 (half‐life: 109.8 min) using our Zymate‐XP robotic system. The process involves (A) a simple one‐step tosyloxy‐for‐fluorine nucleophilic aliphatic substitution (performed at 165°C for 5 min in DMSO using K[18F]F‐Kryptofix®222 and 6.8–7.6 µmol of the corresponding tosylate as precursor for labelling) followed by (B) C‐18 PrepSep cartridge pre‐purification and (C) semi‐preparative HPLC purification on a Waters Symmetry® C‐18. Up to 4.8 GBq (130 mCi) of [18F]PBR111 could be obtained with specific radioactivities ranging from 74 to 148 GBq/µmol (2–4 Ci/µmol) in 75–80 min (HPLC purification and SepPak®‐based formulation included), starting from a 37.0 GBq (1.0 Ci) [18F]fluoride batch. Overall non‐decay‐corrected isolated yields were 8–13% (13–21% decay‐corrected). Copyright © 2008 John Wiley & Sons, Ltd.