bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thallium Determination at the Single Picomole per Liter Level by Flow‐Injection Differential‐Pulse Anodic Stripping Voltammetry
Authors: Jakubowska Monika , Zembrzuski Wlodzimierz , Lukaszewski Zenon 
Published: April 2008

AbstractThe flow‐injection differential‐pulse anodic stripping voltammetric (FI‐DP‐ASV) procedure has been developed for the determination of thallium concentration of the order of the single pM. Due to the analyte preconcentration at the electrode, DPASV is among the leaders in competition for achieving a detection limit as low as possible. The enrichment factor can be easily regulated by the duration of the preconcentration time. A DPASV measurement in a flow‐injection system enables the circulation of an analyzed sample and a medium exchange when preconcentration is completed. This approach ensures significant improvement of a background current. The measurements were performed in a cell of the wall‐jet type containing the mercury film electrode. One hour preconcentration was used for the determination of the lowest thallium concentrations. The developed method provides the opportunity to determine thallium in real environmental samples at the single pM level with the detection limit equal to 0.25 pM and RSD equal to 8.2%. This is by more than one order of magnitude better than the lowest detection limit reported in the literature (5 pM). Additionally, the medium exchange resulted in the improvement of the measuring accuracy, which was evidenced by the application of a certified reference material.
Acetylferrocene Modified Carbon Paste Electrode; A Sensor for Electrocatalytic Determination of Hydrazine
Authors: Ojani Reza , Raoof Jahan‐Bakhsh , Norouzi Banafsheh 
Published: April 2008

AbstractThe electrocatalytic oxidation of hydrazine at a carbon paste electrode spiked with acetylferrocene as a mediator was studied by cyclic voltammetry, differential pulse voltammetry, and chronoamperometry. In contrast to other ferrocenic compounds, acetylferrocene exhibits a chemical irreversible behavior, but it can act as an effective mediator for electrocatalytic oxidation of hydrazine, too. The heterogeneous electron transfer rate constant between acetylferrocene and the electrode substrate (carbon paste) and the diffusion coefficient of spiked acetylferrocene in silicon oil were estimated to be about 3.45×10−4 cm s−1 and 4.45×10−9 cm2 s−1, respectively. It has been found that under the optimum conditions (pH 7.5) the oxidation of hydrazine occurs at a potential of about 228 mV less positive than that of an unmodified carbon paste electrode. The catalytic oxidation peak current of hydrazine was linearly dependent on its concentration and the obtained linear range was 3.09×10−5 M–1.03×10−3 M. The detection limit (2σ) has been determined as 2.7×10−5 M by cyclic voltammetry. Also, the peak current was increased linearly with the concentration of hydrazine in the range of 1×10−5 M–1×10−3 M by differential pulse voltammetry with a detection limit of 1×10−5 M. This catalytic oxidation of hydrazine has been applied as a selective, simple, and precise new method for the determination of hydrazine in water samples.
Voltammetric Reduction of a 4‐Nitroimidazole Derivative on a Multiwalled Carbon Nanotubes Modified Glassy Carbon Electrode
Authors: Jara‐Ulloa P. , Bollo S. , Núñez‐Vergara L. J. , Squella J. A. 
Published: April 2008

AbstractWe report the electrochemical behavior of a 4‐nitroimidazole derivative, 1‐methyl‐4‐nitro‐2‐hydroxymethylimidazole (4‐NImMeOH), on glassy carbon electrode (GCE) modified with multiwalled carbon nanotubes (MWCNT). As dispersing agents, dimethylformamide (DMF) and water were used. The electrochemical response of the resulting electrodes was evaluated using linear sweep, cyclic and square‐wave voltammetry (LSV, CV and SWV). Several parameters such as medium pH, nature and concentration of the CNTs dispersion and accumulation time were tested. The optimal conditions determined for obtain better response were: pH 2, dispersion concentration=4 mg/mL of CNT in water, accumulation time=7 min. The MWCNT‐modified GCE exhibited attractive electrochemical properties producing enhanced currents with a significant reduction in the overpotential and good signal‐to‐noise characteristics, in comparison with the bare GCE. The modified electrode is highly repeatable for consecutive measurements, reaching a variation coefficient of 2.9% for ten consecutive runs.
The primate palette: The evolution of primate coloration
Authors: Bradley Brenda J. , Mundy Nicholas I. 
Published: April 2008

AbstractFlip through The Pictorial Guide to the Living Primates1 and you will notice a striking yet generally underappreciated aspect of primate biology: primates are extremely colorful. Primate skin and pelage coloration were highlighted examples in Darwin's2 original discussions of sexual selection but, surprisingly, the topic has received little research attention since. Here we summarize the patterns of color variation observed across the primate order and examine the selective forces that might drive and maintain this aspect of primate phenotypic diversity. We discuss how primate color patterns might be adaptive for physiological function, crypsis, and communication. We also briefly summarize what is known about the genetic basis of primate pigmentation and argue that understanding the proximate mechanisms of primate coloration will be essential, not only for understanding the evolutionary forces shaping phenotypic variation, but also for clarifying primate taxonomies and conservation priorities.
Citrinin induces apoptosis in mouse embryonic stem cells
Authors: Chan Wen‐Hsiung 
Published: April 2008

AbstractThe mycotoxin citrinin (CTN) is a natural contaminant in foodstuffs and animal feeds, and exerts cytotoxic and genotoxic effects on various mammalian cells. CTN causes cell injury, including apoptosis. However, its precise regulatory mechanisms of action, particularly in stem cells and embryos, are currently unclear. Recent studies show that CTN has cytotoxic effects on mouse embryonic stem cells and blastocysts, and is associated with defects in their subsequent development, both in vitro and in vivo. Experiments with the embryonic stem cell line, ESC‐B5, disclose that CTN induces apoptosis via several mechanisms, including ROS generation, increased cytoplasmic free calcium levels, intracellular nitric oxide production, enhanced Bax/Bcl‐2 ratio, loss of mitochondrial membrane potential, cytochrome c release, activation of caspase‐9 and caspase‐3, and p21‐activated protein kinase 2 and c‐Jun N‐terminal protein kinase activation. Additional studies show that CTN promotes cell death via inactivation of the HSP90/multi‐chaperone complex and subsequent degradation of Ras and Raf‐1, further inhibiting anti‐apoptotic processes such as the Ras→ERK signal transduction pathway. On the basis of these findings, we propose a model for CTN‐induced cell injury signalling cascades in embryonic stem cells and blastocysts. © 2008 IUBMB IUBMB Life, 60(3): 171–179, 2008
Multidomain STS/TULA proteins are novel cellular regulators
Authors: Tsygankov Alexander Y. 
Published: April 2008

AbstractProteins of the STS/TULA family recently emerged as important regulators of cellular functions. They exhibit a unique domain architecture, featuring at least three interactive/functional domains. Despite a significant degree of homology between the two members of this family, there are considerable functional differences between them. Thus, one of them is ubiquitously expressed in mammalian tissues and exhibits high phosphatase activity, whereas the other one is expressed in lymphocytes only and exhibits very low phosphatase activity, but is capable of promoting apoptosis, an activity unique for this family member. Among several functions reported for STS/TULA proteins, the most characterized one is the regulation of protein tyrosine kinase‐mediated signaling. Interestingly, gene deletion of neither family member results in a discernible phenotype, whereas simultaneous deletion of both members causes hyperreactivity of T cells. Despite their apparent importance, the physiological role and the molecular basis of the effects of STS/TULA proteins remain poorly understood. This brief review summarizes what is currently known about the STS/TULA family and outlines the unresolved questions in this area. © 2008 IUBMB IUBMB Life, 60(4): 224–231, 2008
Eukaryotic selenoprotein synthesis: Mechanistic insight incorporating new factors and new functions for old factors
Authors: Squires Jeffrey E. , Berry Marla J. 
Published: April 2008

AbstractSelenium is an essential micronutrient that has been linked to various aspects of human health. Selenium exerts its biological activity through the incorporation of the amino acid, selenocysteine (Sec), into a unique class of proteins termed selenoproteins. Sec incorporation occurs cotranslationally at UGA codons in archaea, prokaryotes, and eukaryotes. UGA codons specify Sec coding rather than termination by the presence of specific secondary structures in mRNAs termed selenocysteine insertion (SECIS) elements, and trans‐acting factors that associate with SECIS elements. Herein, we discuss the various proteins known to function in eukaryotic selenoprotein biosynthesis, including several players whose roles have only been elucidated very recently. © 2008 IUBMB IUBMB Life, 60(4): 232–235, 2008
Resveratrol: One molecule, many targets
Authors: Pirola Luciano , Fröjdö Sara 
Published: April 2008

AbstractResveratrol is one of the numerous polyphenolic compounds found in several vegetal sources. In recent years, the interest in this molecule has increased exponentially following the major findings that resveratrol (i) is shown to be chemopreventive in some cancer models, (ii) is cardioprotective, and (iii) has positive effects on several aspects of metabolism, leading to increased lifespan in all the metazoan models tested thus far, including small mammals. Such remarkable properties have elicited a vast interest towards the identification of target proteins of resveratrol and have led to the identification of enzymes inhibited by resveratrol and others whose activation is enhanced. In the vast majority of cases, resveratrol displays inhibitory/activatory effects in the micromolar range, which is potentially attainable pharmacologically, although targets with affinities in the nanomolar range have also been reported. Here, we provide an overview of the various classes of enzymes known to be inhibited (or activated) by resveratrol. It appears that resveratrol, as a pharmacological agent, has a wide spectrum of targets. The biological activities of resveratrol may thus be dependent on its simultaneous activity on multiple molecular targets. © 2008 IUBMB IUBMB Life, 60(5): 323–332, 2008
Trapping of human DNA topoisomerase I by DNA structures mimicking intermediates of DNA repair
Authors: Lebedeva Natalia , Rechkunova Nadejda , Boiteux Serge , Lavrik Olga 
Published: April 2008

AbstractIn this report we show that human DNA Topoisomerase I (Top1) forms DNA‐protein adducts with nicked and gapped DNA structures lacking a conventional Top1 cleavage site. The radioactively labeled crosslinking products were identified by SDS‐gel electrophoresis. The chemical structure of the groups at 5′ or 3′ end of the nick does not have an effect on the formation of these covalent adducts. Therefore, all kinds of nicks, either directly induced by ionizing radiation or reactive oxygen species or indirectly induced in the course of base excision repair (BER) are targets for Top1 that competes with BER proteins and other nick‐sensors. Top1‐DNA covalent adducts formed in cells exposed to DNA damaging agents can promote genetic instability. © 2008 IUBMB IUBMB Life, 60(2): 130–134, 2008
Mechanisms of aging and energy metabolism in Caenorhabditis elegans
Authors: Artal‐Sanz Marta , Tavernarakis Nektarios 
Published: April 2008

AbstractAging studies on diverse species ranging from yeast to man have culminated in the delineation of several signaling pathways that influence the process of senescent decline and aging. While understanding these interlinked signal‐transduction cascades is becoming even more detailed and comprehensive, the cellular and biochemical processes they impinge upon to modulate the rate of senescent decline and aging have lagged considerably behind. This fundamental question is one of the most important challenges of modern aging research and has been the focus of recent research efforts. Emerging findings provide insight into the facets of cellular metabolism which can be fine‐tuned by upstream signaling events to ultimately promote longevity. Here, we survey the mechanisms regulating aging in the simple nematode worm Caenorhabditis elegans, aiming to highlight recent discoveries that shed light into the interface between aging signaling pathways and cellular energy metabolism. Our objective is to review the current understanding of the processes involved and discuss mechanisms that are likely conserved in higher organisms. © 2008 IUBMB IUBMB Life, 60(5): 315–322, 2008
Thermo‐triggered and biotinylated biotin‐P(NIPAAm‐co‐HMAAm)‐b‐PMMA micelles for controlled drug release
Authors: Cheng Cheng , Wei Hua , Zhang Xian‐Zheng , Cheng Si‐Xue , Zhuo Ren‐Xi 
Published: April 2008

AbstractThermosensitive and biotinylated biotin‐poly (N‐isopropylacrylamide‐co‐N‐hydroxymethylacrylamide)‐block‐poly(methyl methacrylate) (biotin‐P(NIPAAm‐co‐HMAAm)‐b‐PMMA) block copolymers were designed and synthesized. The conjugation of biotin molecule with the copolymer as well as the capability of easily functionalizing with ligands for pretargeting approach of the biotinylated multifunctional drug carrier was confirmed by a novel method called capillary electrophoresis immunoassay (CEIA) based on enhanced chemiluminescence (CL) detection. The biotin‐P(NIPAAm‐co‐HMAAm)‐b‐PMMA copolymer was capable of self‐assembling into nanometer‐sized micelle. The anticancer drug methotrexate (MTX), used as a model drug, was loaded in the self‐assembled micelles and the thermo‐triggered release behavior of MTX was investigated. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Long‐term evaluation of blood silicon and ostecalcin in operatively treated patients with benign bone tumors using bioactive glass and autogenous bone
Authors: Lindfors N. C. , Heikkilä J. T. , Aho A. J. 
Published: April 2008

AbstractIn a study on 25 patients with verified benign bone tumors, bioactive glass (BG) and autogenous bone (AB) were used as bone‐graft substitutes. The patients were randomized into two groups according to the filling material. Blood samples were taken both preoperatively, at 2 weeks, and 3, 8, 12, 24, and 36 months postoperatively, for evaluation of silicon concentration in blood. In the determination, direct current plasma atomic emission spectroscopy was used. No significant difference in blood silicon concentration between the BG group or the AB group could statistically be observed (p = 0.5400), and neither did the size of the bone tumor (p = 0.4259) nor the follow‐up time affect the results (p = 0.2094). Concentration of osteocalcin in blood was significantly higher for large cysts (p < 0.0001). The filler material (BG or AB) did not affect the osteocalcin concentration level in blood. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
Using support vector machine to predict β‐ and γ‐turns in proteins
Authors: Hu Xiuzhen , Li Qianzhong 
Published: April 2008

AbstractBy using the composite vector with increment of diversity, position conservation scoring function, and predictive secondary structures to express the information of sequence, a support vector machine (SVM) algorithm for predicting β‐ and γ‐turns in the proteins is proposed. The 426 and 320 nonhomologous protein chains described by Guruprasad and Rajkumar (Guruprasad and Rajkumar J. Biosci 2000, 25,143) are used for training and testing the predictive model of the β‐ and γ‐turns, respectively. The overall prediction accuracy and the Matthews correlation coefficient in 7‐fold cross‐validation are 79.8% and 0.47, respectively, for the β‐turns. The overall prediction accuracy in 5‐fold cross‐validation is 61.0% for the γ‐turns. These results are significantly higher than the other algorithms in the prediction of β‐ and γ‐turns using the same datasets. In addition, the 547 and 823 nonhomologous protein chains described by Fuchs and Alix (Fuchs and Alix Proteins: Struct Funct Bioinform 2005, 59, 828) are used for training and testing the predictive model of the β‐ and γ‐turns, and better results are obtained. This algorithm may be helpful to improve the performance of protein turns' prediction. To ensure the ability of the SVM method to correctly classify β‐turn and non‐β‐turn (γ‐turn and non‐γ‐turn), the receiver operating characteristic threshold independent measure curves are provided. © 2008 Wiley Periodicals, Inc. J Comput Chem 2008
Unusual Sb–Sb bonding in high temperature thermoelectric materials
Authors: Xu Jianxiao , Kleinke Holger 
Published: April 2008

AbstractThe emerging families of advanced thermoelectrics are dominated by antimonides and tellurides. Because the structures of the tellurides are mostly composed of NaCl‐related motifs, they do not contain any Te–Te bonds, and all of the antimonide structures exhibit Sb–Sb bonds of various lengths. Taking all Sb–Sb distances shorter than 3.2 Å into account, the Sb atom substructures are Sb24− pairs in β‐Zn4Sb3, linear Sb37− units in Yb14MnSb11, planar Sb44− rectangles in the skutterudites, for example, LaFe3CoSb12, and Sb8 cubes interconnected via short Sb–Sb bonds to a three‐dimensional network in Mo3Sb5Te2. These interactions have a significant impact on the band gap size as well as on the effective mass around the Fermi level, for the bottom of the conduction band is in all cases predominated by antibonding Sb–Sb interactions, and—in some cases—the top of the valence band by bonding Sb–Sb interactions. © 2008 Wiley Periodicals, Inc. J Comput Chem 2008
Are Ba11Cd6Sb12 and Sr11Cd6Sb12 Zintl phases or not? A density‐functional theory study
Authors: Xia Sheng‐Qing , Bobev Svilen 
Published: April 2008

AbstractThe chemical bonding and the electronic band structures of two isoelectronic and isostructural Zintl compounds, Sr11Cd6Sb12 and Ba11Cd6Sb12, have been studied on the basis of the density‐functional theory (DFT) using the tight‐binding linear‐muffin‐tin‐orbital (TB‐LMTO‐ASA) approach and the local‐density approximation (LDA). These results reveal that the classic Zintl reasoning and the concept of two‐center two‐electron bonds cannot explain the subtleties of this complex structure type. The computations also suggest that the antimony dimers present in these structures play an important role and allow for a greater flexibility in optimization of the bonding with the surrounding d‐metal atoms. © 2008 Wiley Periodicals, Inc. J Comput Chem 2008
Exploring the conformational space of Vpu from HIV‐1: A versatile adaptable protein
Authors: Krüger Jens , Fischer Wolfgang B. 
Published: April 2008

AbstractThe dynamic behavior of monomeric Vpu1‐32 from HIV‐1 in different lipid environments has been studied. The peptide shows highly flexible behavior during the simulations and easily adapts to changing lipid environments as it experiences when travelling through the Golgi apparatus. Protein–lipid interactions do not show any significant correlation towards lipid type or thickness based on multiple 10 ns simulations. The averaged structure of a series of 16 independent simulations suggest kink around Ser‐24, which compensates the polarity of its side chain by forming hydrogen bonds with the carbonyl backbone of adjacent amino acids towards the N‐terminus. © 2008 Wiley Periodicals, Inc. J Comput Chem 2008.
Branchial arch muscle innervation by the glossopharyngeal (IX) and vagal (X) nerves in Tetraodontiformes, with special reference to muscle homologies
Authors: Nakae Masanori , Sasaki Kunio 
Published: April 2008

AbstractBranchial arch muscle innervation by the glossopharyngeal (IX) and vagal (X) nerves in 10 tetraodontiform families and five outgroup taxa was examined, with special reference to muscle homologies. Basic innervation patterns and their variations were described for all muscle elements (except gill filament muscles). In the tetraodontids Takifugu poecilonotus and Canthigaster rivulata, diodontid Diodon holocanthus, and molid Mola mola, levator externus 4 was innervated by the 3rd vagal branchial trunk (BX3) in addition to BX2, owing to strong posterior expansion of the muscle. Based on nerve innervation, migrations of the muscle attachment sites (i.e., origins and insertions) were recognized in levator internus 2 (in Mola mola), obliquus dorsalis 3 (in Ostracion immaculatus and Canthigaster rivulata), and obliquus ventralis 2 (in Stephanolepis cirrhifer), muscle topologies not necessarily being indicative of homologies. Embryonic origin of the retractor dorsalis and parallel attainment of the swimbladder muscle within the order were also discussed. J. Morphol., 2008. © 2008 Wiley‐Liss, Inc.
Promotion of neuronal differentiation through activation of N‐methyl‐D‐aspartate receptors transiently expressed by undifferentiated neural progenitor cells in fetal rat neocortex
Authors: Yoneyama Masanori , Nakamichi Noritaka , Fukui Masaki , Kitayama Tomoya , Georgiev Danko D. , Makanga Juliet O. , Nakamura Nobuhiro , Taniura Hideo , Yoneda Yukio 
Published: April 2008

AbstractNeural progenitor cell is a generic term for undifferentiated cell populations composed of neural stem, neuronal progenitor, and glial progenitor cells with abilities for self‐renewal and multipotentiality. In this study, we have attempted to evaluate the possible functional expression of N‐methyl‐D‐aspartate (NMDA) receptors by neural progenitor cells prepared from neocortex of 18‐day‐old embryonic rats. Cells were cultured in the presence of basic fibroblast growth factor (bFGF) for different periods up to 12 days under floating conditions. Reverse transcription‐polymerase chain reaction and fluorescence imaging analyses revealed transient expression of functional NMDA receptors in neurospheres formed by clustered progenitors during the culture with bFGF. A similarly potent increase was seen in the fluorescence intensity after brief exposure to NMDA in cells differentiated after the removal of bFGF under adherent conditions, and an NMDA receptor antagonist invariably prevented these increases by NMDA. Moreover, sustained exposure to NMDA not only inhibited the formation of neurospheres when exposed for 10 days from day 2 to day 12 but also promoted spontaneous and induced differentiation of neurospheres to cells immunoreactive for a neuronal marker protein on immunocytochemistry and Western blotting analyses. These results suggest that functional NMDA receptors may be transiently expressed to play a role in mechanisms underlying the modulation of proliferation along with the determination of subsequent differentiation fate toward a neuronal lineage in neural progenitor cells of developing rat neocortex. © 2008 Wiley‐Liss, Inc.