bluuebunny/crossref_metadata_2025_split huggingface dataset:
Slowly Exchanging cis‐PtA2B2 Atropisomers with A2 = Chiral Diamine Ligands and B = 5,6‐Dimethylbenzimidazole
Authors: Trani Manuela , Cannito Francesco , Natile Giovanni , Marzilli Patricia A. , Marzilli Luigi G. 
Published: June 2005

Abstractcis‐PtA2G2 complexes, in which A2 is a bidentate amine ligand and G is a unidentate guanine derivative bound to platinum through N7, are simple models of the G‐G cross‐link DNA lesion formed by the anticancer drug cisplatin. Rotation of the G bases about the Pt–N7 bonds is usually rapid except for bulky amine ligand(s). This paper concerns cis‐PtA2(Me2Bzm)2 adducts [A2 = 2,2'‐bipiperidine (Bip)and N,N,N',N'‐tetramethyl‐2,3‐diaminobutane (Me4DAB); Me2Bzm = 5,6‐dimethylbenzimidazole] for which the interconversion among possible rotamers (one HH and two HT) is slow on the NMR time scale. The amounts of the rarely observed HH conformer were 52 and 37 % at 5 °C for BipPt(Me2Bzm)2 and Me4DABPt(Me2Bzm)2, respectively, and increased to 60 and 44 % at 50 °C. This result represents the first reported clear evidence for the existence of the HH atropisomer in cis‐PtA2B2 adducts (B = G or Me2Bzm base) with fully substituted diamines, such as Me4DAB or Me4EN (Me4EN = N,N,N',N'‐tetramethyl‐1,2‐diaminoethane). The lack of an O‐substituent on the C4 atom of Me2Bzm (corresponding to C6 of G) undoubtedly allows for a relatively stable HH conformer. Thermodynamic parameters confirm the crucial role of the substituents in positions 4 and 6 of the base systems (for Me2Bzm and G derivatives, respectively) in determining the stability of different rotamers. The greater abundance of the HH rotamer for BipPt(Me2Bzm)2 than for Me4DABPt(Me2Bzm)2 indicates that an increase in the steric bulk of the carrier ligand favors the HT rotamers over the HH rotamer. For both BipPt(Me2Bzm)2 and Me4DABPt(Me2Bzm)2 adducts, the major HT rotamer has the six‐membered ring of each Me2Bzm ligand on the more crowded side of the cis amine with respect to the platinum coordination plane: the N–CH2– group in Bip and the N–Meeq (N–Meeq = quasi‐equatorial N–Me) in Me4DAB adducts. The latter result is in complete agreement with previous findings from our laboratories concerning BipPtG2 and Me4DABPtG2 compounds and gives further support to the view that the major HT rotamer is stabilized by the six‐membered ring of each base canted toward the cis base. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
[1]Borahafnocenophanes: Synthesis, Structure and Catalytic Activity
Authors: Braunschweig Holger , Kraft Mario , Radacki Krzysztof , Stellwag Sascha 
Published: June 2005

AbstractVarious [1]borahafnocenophanes of the general formula[R2NB(η5‐C5H4)2HfCl2] [R = CH3, 13; R = C2H5, 14; R2 =(CH2)5, 15] were synthesised in high yields by a convenient two‐step, one‐pot synthesis, and their constitution in solution elucidated from multinuclear NMR spectroscopic data. Suitable single crystals of complexes 13 and 15 were subjected to X‐ray diffraction studies, thus providing the first structural data of [1]borahafnocenophanes. The catalytic activity of the new complexes in the Ziegler–Natta polymerisation of ethylene was studied and compared to that of corresponding [1]borazirconocenophanes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Design, Preparation and Characterization of the Adducts of the Bis‐Amido Cobalticinium Complex [CoIII(η5‐C5H4CONHC5H4N)2][PF6] with Fumaric and Maleic Acids
Authors: Braga Dario , Giaffreda Stefano L. , Polito Marco , Grepioni Fabrizia 
Published: June 2005

AbstractThe supramolecular hydrogen‐bonded adducts obtained by treating the cationic bis‐amido complex [CoIII(η5‐C5H4CONHC5H4N)2]+ with fumaric and maleic acid are investigated and their modes of aggregation in the solid state are explored. It is shown that the bis‐amido organometallic complex can be mono‐ and di‐protonated in the reaction with the dicarboxylic acids, leading to the formation of complex, mixed‐anion supramolecular salts containing either the dication [CoIII(η5‐C5H4CONHC5H4N)(η5‐C5H4CONHC5H4NH)]2+, [1H]2+, or the trication [CoIII(η5‐C5H4CONHC5H4NH)2]3+, [1H2]3+. The derivatives of the reaction with fumaric acid, namely, [CoIII(η5‐C5H4CONHC5H4N)(η5‐C5H4CONHC5H4NH)]2+·[PF6]–·1/2[fumarate]2–, [1H]2+·PF6–·1/2[fumarate]2–, and [CoIII(η5‐C5H4CONHC5H4NH)2]3+·[PF6]–·[H(fumarate)2]3–·H3O+·H2O, [1H2]3+·[PF6]–·[H(fumarate)2]3–·H3O+·H2O, contain either the dianion [fumarate]2– or the hydrogen‐bridged supramolecular trianion [H(fumarate)2]3–, depending on the amide/acid stoichiometric ratio. In the case of maleic acid, on the other hand, the possibility of intramolecular hydrogen‐bond formation generates exclusively salts of the hydrogen maleate anions, namely, [CoIII(η5‐C5H4CONHC5H4N)(η5‐C5H4CONHC5H4NH)]2+·5/2[PF6]–·3/2[Hmaleate]–, 2[1H]2+·5/2[PF6]–·3/2[Hmaleate]–, 2[CoIII(η5‐C5H4CONHC5H4NH)2]3+·3[PF6]–·3[Hmaleate]–·2H2O, 2[1H2]3+·3[PF6]–·3[Hmaleate]–·2H2O and [CoIII(η5‐C5H4CONHC5H4NH)2]3+·2[PF6]–·[Hmaleate]–·H2O, [1H2]3+·2[PF6]–·[Hmaleate]–·H2O, in which the hydrogen maleate anions act as bridges between the protonated bis‐amido organometallic sandwiches. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
ChiralN‐Acylhydrazones: Versatile Imino Acceptors for Asymmetric Amine Synthesis
Authors: Friestad Gregory K. 
Published: June 2005

AbstractAddition to C=N bonds with acyclic stereocontrol offers excellent potential for development of new carbon–carbon bond construction approaches to chiral amines. This review features the design and implementation of novel chiralN‐acylhydrazones as versatile imino acceptors for addition of radicals and nucleophiles. The initial design was inspired by the goal of asymmetric radical addition to chiral C=N radical acceptors. The chiralN‐acylhydrazones are prepared from commercially available materials by amination of 4‐alkyl‐2‐oxazolidinones with NH2+equivalents to affordN‐(amino)oxazolidinones, followed by condensation with aldehydes or ketones. These chiralN‐acylhydrazones undergo addition reactions with various partners, including radicals, allylsilanes, allylindiums, silyl enol ethers, and hydride donors. The adducts can be converted to chiral amines by N–N bond cleavage. Reliably high stereoselectivity was observed for addition reactions in the presence of Lewis acids. For the prototype case,N‐acylhydrazones derived from (S)‐4‐benzyl‐2‐oxazolidinone, two alternative stereocontrol models are consistent with the results. Lewis acids capable of chelate formation activate through two‐point binding of the imino nitrogen and the carbonyl oxygen, exposing thesi‐face for addition. On the other hand, boron trifluoride activates through a monodentate interaction, favoring a rotamer which exposes there‐face. Applications from the author’s research program are reviewed together with results from other groups. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Analysis of carboxylic acids in biological fluids by capillary electrophoresis
Authors: Baena Beatriz , Cifuentes Alejandro , Barbas Coral 
Published: June 2005

AbstractThis review article addresses the different capillary electrophoretic methods that are being used for the study of both short‐chain organic acids (including anionic catecholamine metabolites) and fatty acids in biological samples. This work intends to provide an updated overview (including works published until November 2004) on the recent methodological developments and applications of such procedures together with their main advantages and drawbacks. Moreover, the usefulness of CE analysis of organic acids to study and/or monitor different diseases such as diabetes, new‐borns diseases or metabolism disorders is examined. The use of microchip devices and CE‐MS couplings for organic acid analysis is also discussed.
High‐throughput gender determination using automated denaturant gel capillary electrophoresis
Authors: Hinselwood David C. , Warren David J. , Ekstrøm Per O. 
Published: June 2005

AbstractSex determination of anonymous samples is a requirement before analysis of DNA variation on X or Y chromosomes. Based on this, we designed a method for screening samples on different DNA capillary sequencing instruments with a sensitivity that is able to quantify sex chromosome abnormalities. The two different amelogenin alleles sited on the X and Y chromosomes were polymerase chain reaction amplified with the same set of primers and separated by denaturant capillary electrophoresis (DCE). Sex chromosome ratios could be reproducibly determined with a relative standard deviation of 8.7%, which is sufficient to distinguish a normal XY karyotype from an XYY karyotype associated with Klinefelter syndrome. Reconstruction experiments demonstrated sensitivity down to a simulated Y:X allelic ratio of 1:127 in all three instruments, enabling the prediction of sex chromosomal aneuploidies. When tested on anonymous pooled and single samples, DCE gave a good prediction of the male to female ratio in pools of 1000 blood donors. In conclusion, DCE is a simple and robust method for sex determination that can be readily performed on commercially available CE systems.
Review of denaturant capillary electrophoresis in DNA variation analysis
Authors: Bjørheim Jens , Ekstrøm Per Olaf 
Published: June 2005

AbstractAnalyses of germline and somatic single‐nucleotide DNA variations are important in both population genetics research and clinical practice. Reliable and inexpensive methods that are flexible and designed for automation are required for these analyses. Present day DNA sequencing technology is too expensive for testing all 22–25 000 human genes in populations genetics studies or in scanning large numbers of tumors for novel mutations. Denaturant capillary electrophoresis (DCE) has the potential to meet the need for large‐scale analysis of DNA variants. Several different analyses can be performed by DCE, including mutation analysis, single‐nucleotide polymorphism (SNP) discovery in individual and pooled samples, detection of allelic imbalance, and determination of microhaplotypes. Here we review the theoretical background of the method, its sensitivity, specificity, detection limit, throughput, and repeatability in the light of current literature in the field.
Locus‐specific brackets for reliable typing of Y‐chromosome short tandem repeat markers
Authors: Butler John M. , Appleby Jill E. , Duewer David L. 
Published: June 2005

AbstractShort tandem repeat (STR) loci, widely used as genetic markers in disease diagnostic studies and human identity applications, are traditionally genotyped through comparison of allele sizes to a sequenced allelic ladder. Allelic ladders permit a floating bin allele calling method to be utilized, which enables reliable allele calling across laboratories, instrument platforms, and electrophoretic conditions. Precise sizing methods for STR allele calling involving fixed bins can also be used when a high degree of precision has been demonstrated within an instrument platform and a set of electrophoretic conditions. An alternative method for reliable genotyping of STR markers, locus‐specific brackets (LSBs), is introduced here. LSBs are artificial alleles created through molecular biology manipulations to be shorter or longer than alleles commonly seen in populations under investigation. The size and repeat number of measured alleles are interpolated between the two LSB products that are mixed with the polymerase chain reaction‐amplified STR alleles. The advantages and limitations of the LSB approach are described along with a concordance study between the LSB typing approach and other STR typing methods. Complete agreement was observed with 162 samples studied at 5 Y‐chromosome loci.
Direct targeting of human plasma for matrix‐assisted laser desorption/ionization and analysis of plasma proteins by time of flight‐mass spectrometry
Authors: Jin Ya , Manabe Takashi 
Published: June 2005

AbstractA method to analyze human plasma proteins without fractionation, directly applying a plasma‐matrix mixture on the target plate of a matrix‐assisted laser desorption/ionization‐time of flight‐mass spectrometer (MALDI‐TOF‐MS), has been described. Peaks of ionized plasma proteins could not be detected applying a mixture of an undiluted plasma sample and a matrix solution, but they appeared when the plasma was diluted before mixing with the matrix. Tenfold diluted plasma provided well‐resolved protein peaks in the m/z range from 4000 to 30 000. The addition of a simple post‐crystallization washing procedure performed on the target plate further improved the quality of mass spectra. We numbered 58 peaks in the range of 4–160 kDa and 32 out of which were assigned to the plasma protein species which have been reported. Especially high sensitivity and resolution were obtained in the region < 30 kDa, where multiple isoforms of apolipoprotein A‐I, apolipoprotein A‐II, apolipoprotein C‐I, apolipoprotein C‐II, apolipoprotein C‐III, and transthyretin could be assigned. Various post‐translational modifications are involved in the isoforms, e.g., proteolytic cleavage, glycosylation and chemical modifications. This method will become complementary with the present electrophoretic techniques, especially for the analysis of low‐molecular‐mass proteins.
Determination of mercaptopurine and its four metabolites by large‐volume sample stacking with polarity switching in capillary electrophoresis
Authors: Wang Chun‐Chi , Chiou Shyh‐Shin , Wu Shou‐Mei 
Published: June 2005

AbstractThis study describes approaches for stacking a large volume of sample solutions containing a mixture of mercaptopurine monohydrate, 6‐methylmercaptopurine, thioguanine, thioguanosine, and thioxanthine in capillary electrophoresis (CE). After filling the run buffer (60 mM borate buffer, pH 8.5), a large sample volume was loaded by hydrodynamic injection (2.5 psi, 99.9 s), followed by the removal of the large plug of sample matrix from the capillary using polarity switching (−15 kV). Monitoring the current and reversing the polarity when 95% of current recovered, the separation of anionic analytes was performed in a run buffer < 20 kV. Around 44‐ to 90‐fold improvement of sensitivity for five analytes was achieved by large‐volume stacking with polarity switching when compared with CE without stacking. This method was feasible for determination of the analytes spiked in plasma. Removing most of electrolytes from plasma is a key step for performing large‐volume sample stacking. Solid‐phase extraction was used for pretreatment of biological samples. To our knowledge, this study is one of few applications showing the possibilities of this stacking procedure to analyze biological samples by large‐volume sample stacking with polarity switching (LVSSPS) in CE.
Phonological decoding involves left posterior fusiform gyrus
Authors: Dietz Nicole A.E. , Jones Karen M. , Gareau Lynn , Zeffiro Thomas A. , Eden Guinevere F. 
Published: June 2005

AbstractAloud reading of novel words is achieved by phonological decoding, a process in which grapheme‐to‐phoneme conversion rules are applied to “sound out” a word's spoken representation. Numerous brain imaging studies have examined the neural bases of phonological decoding by contrasting pseudoword (pronounceable nonwords) to real word reading. However, only a few investigations have examined pseudoword reading under both aloud and silent conditions, task parameters that are likely to significantly alter the functional anatomy of phonological decoding. Subjects participated in an fMRI study of aloud pseudoword, aloud real word, silent pseudoword, and silent real word reading. Using this two‐by‐two design, we examined effects of word‐type (real words vs. pseudowords) and response‐modality (silent vs. aloud) and their interactions. We found 1) four regions to be invariantly active across the four reading conditions: the anterior aspect of the left precentral gyrus (Brodmann's Area (BA) 6), and three areas within the left ventral occipitotemporal cortex; 2) a main effect of word‐type (pseudowords > words) in left inferior frontal gyrus and left intraparietal sulcus; 3) a main effect of response‐modality (aloud > silent) that included bilateral motor, auditory, and extrastriate cortex; and 4) a single left hemisphere extrastriate region showing a word‐type by response‐modality interaction effect. This region, within the posterior fusiform cortex at BA 19, was uniquely modulated by varying phonological processing demands. This result suggests that when reading, word forms are subject to phonological analysis at the point they are first recognized as alphabetic stimuli and BA 19 is involved in processing the phonological properties of words. Hum Brain Mapp, 2005. © 2005 Wiley‐Liss, Inc.
Semiparametric estimation of lifetime equivalence scales
Authors: Pendakur Krishna 
Published: June 2005

AbstractPashardes (1991) and Bankset al.(1994) use parametric methods to estimate lifetime equivalence scales. Their approaches put parametric restrictions on the differences in within‐period expenditure needs across household types, the intertemporal allocation of expenditure, and the shapes of commodity demand equations. This paper puts parametric structure only on the differences in within‐period expenditure needs across household types. This implies structure on the intertemporal allocation of expenditure, but leaves the shapes of commodity demand equations unrestricted. Semiparametric methods are used to estimate within‐period and lifetime equivalence scales with Canadian expenditure data, and to test the restrictions imposed on within‐period expenditure functions. Estimated lifetime equivalence scales are similar in size to those estimated by Bankset al.(1994) and exhibit equal lifetime costs for first and second children. Copyright © 2005 John Wiley & Sons, Ltd.
Effects of soluble metals on human peri‐implant cells
Authors: Hallab Nadim James , Anderson Shelley , Caicedo Marco , Brasher Amee , Mikecz Katalin , Jacobs Joshua J. 
Published: June 2005

AbstractDespite reports associating tissue necrosis with implant failure, the degree to which processes, such as metal toxicity, negatively impact implant performance is unknown. We evaluated representative human peri‐implant cells (i.e., osteoblasts, fibroblasts, and lymphocytes) when challenged by Al+3, Co+2, Cr+3, Fe+3, Mo+5, Ni+2, and V+3 chloride solutions (and Na+2 as a control) over a wide range of concentrations (0.01–10.0 mM). Cell responses were measured using proliferation assays, viability assays, and microscopic cell morphology assessments. Differential effects were found to be less a function of the cell type than of the composition and concentration of metal challenge. No preferential immunosuppression was demonstrated. Below 0.01 mM, no metal was toxic. The most toxic metals (i.e., Co, Ni, and V) reduced proliferation (IC50), and viability (LC50) and cell morphology of osteoblasts, fibroblasts, and lymphocytes by <50% at challenge concentrations <1 mM. All other metals tested required >5 mM to exact the same responses. Below 1 mM, these toxic metals also induced alterations in all cell morphology consisting of loss of filopodia or lamellipodia or changes in cell shape. Metals that were toxic at clinically relevant concentrations (less than previously reported values in peri‐implant tissues/fluids) include Co (0.6 mM), Ni (0.8 mM), V (0.5 mM) for lymphocytes and Co (0.8 mM), V (0.3 mM), Al (1–5 mM), Fe (1–5 mM) for fibroblasts, and Co (0.8 mM), Ni (0.7 mM), V (0.1 mM) for osteoblasts. Only Co and V were toxic in vitro at concentrations below that detected in vivo in synovial fluid (V at 0.1 mM and Co at 0.8 mM for fibroblasts, and V at 0.4 mM and Co at 0.8 mM on osteoblasts). Thus, soluble Co and V released from Co‐ and Ti‐based alloys, respectively, could be implicated as the most likely to mediate cell toxicity in the periprosthetic milieu. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2005
Cycle‐cocycle partitions and faithful cycle covers for locally finite graphs
Authors: Bruhn Henning , Diestel Reinhard , Stein Maya 
Published: June 2005

AbstractBy a result of Gallai, every finite graph G has a vertex partition into two parts each inducing an element of its cycle space. This fails for infinite graphs if, as usual, the cycle space is defined as the span of the edge sets of finite cycles in G. However, we show that, for the adaptation of the cycle space to infinite graphs recently introduced by Diestel and Kühn (which involves infinite cycles as well as finite ones), Gallai's theorem extends to locally finite graphs. Using similar techniques, we show that if Seymour's faithful cycle cover conjecture is true for finite graphs then it also holds for locally finite graphs when infinite cyles are allowed in the cover, but not otherwise. We also consider extensions to graphs with infinite degrees. © 2005 Wiley Periodicals, Inc. J Graph Theory
Organic mass spectrometry in archaeology: evidence for Brassicaceae seed oil in Egyptian ceramic lamps
Authors: Colombini Maria Perla , Modugno Francesca , Ribechini Erika 
Published: June 2005

AbstractAn analytical procedure based on alkaline hydrolysis and silylation followed by GC/MS analysis was employed to study the formation of characteristic acidic compounds and the development of a distinctive chromatographic pattern in the course of accelerated ageing tests on Brassicaceae seed oil. On the basis of mass spectra of trimethylsilyl derivatives, the main degradation products were identified as α,ω‐dicarboxylic, ω‐hydroxycarboxylic and dihydroxycarboxylic acids, including 11,12‐dihydroxyeicosanoic acid and 13,14‐dihydroxydocosanoic acid. The mass spectra of both these compounds are characterised by fragment ions arising from the α cleavage of the bond between the two vicinal trimethylsiloxy groups, resulting in fragments at m/z 215 and 345 for 11,12‐dihydroxyeicosanoic acid, and at m/z 215 and 373 for 13,14‐dihydroxydocosanoic acid. Other significant fragment ion‐radicals from rearrangement process at m/z [M − 90]+•, [M − 142]+•, 204 as well as fragment ions at m/z [M − 15]+, [M − 105]+, 217 are present in the mass spectra of both the compounds. The results obtained for reference materials were compared with those relating to archaeological organic materials recovered in Egyptian pottery lamps. The occurrence of the same characteristic degradation products found in the reference materials subjected to accelerated ageing indicates an unambiguous origin for the organic archaeological remains and represents the chemical evidence for the use of oil from seeds of Brassicaceae as illuminant. Copyright © 2005 John Wiley & Sons, Ltd.
Chromophore effect in photodissociation at 266 nm of protonated peptides generated by matrix‐assisted laser desorption ionization (MALDI)
Authors: Oh Joo Yeon , Moon Jeong Hee , Kim Myung Soo 
Published: June 2005

AbstractChromophore effect in the photodissociation of protonated peptides at 266 nm was investigated using synthetic peptides with the sequence RGGXGGGGGR where X was a phenylalanyl(F), tyrosyl(Y), cysteinyl(C), glycyl(G), seryl(S), or histidyl(H) residue. The peptides with an F or Y residue dissociated efficiently. Fragment ions due to cleavages at either end of the chromophore were especially prominent just as for the peptide with a tryptophanyl residue reported previously.1Photodissociation was observed even for the peptides without any noticeable chromophore at 266 nm. Here, dissociation at all the peptide bonds was almost equally prominent. Photodissociation of the protonated angiotensin I was investigated using the spectral correlation rules observed in the model systems. Role of the chromophores and the plausible mechanisms involved are discussed. Copyright © 2005 John Wiley & Sons, Ltd.