bluuebunny/crossref_metadata_2025_split huggingface dataset:
Engineering a G protein‐coupled receptor for structural studies: Stabilization of the BLT1 receptor ground state
Authors: Martin Aimée , Damian Marjorie , Laguerre Michel , Parello Joseph , Pucci Bernard , Serre Laurence , Mary Sophie , Marie Jacky , Banères Jean‐Louis 
Published: February 2009

AbstractStructural characterization of membrane proteins is hampered by their instability in detergent solutions. We modified here a G protein‐coupled receptor, the BLT1 receptor of leukotriene B4, to stabilize it in vitro. For this, we introduced a metal‐binding site connecting the third and sixth transmembrane domains of the receptor. This modification was intended to restrain the activation‐associated relative movement of these helices that results in a less stable packing in the isolated receptor. The modified receptor binds its agonist with low‐affinity and can no longer trigger G protein activation, indicating that it is stabilized in its ground state conformation. Of importance, the modified BLT1 receptor displays an increased temperature‐, detergent‐, and time‐dependent stability compared with the wild‐type receptor. These data indicate that stabilizing the ground state of this GPCR by limiting the activation‐associated movements of the transmembrane helices is a way to increase its stability in detergent solutions; this could represent a forward step on the way of its crystallization.
Insights into the catalytic mechanism of the Bcp family: Functional and structural analysis of Bcp1 from Sulfolobus solfataricus
Authors: D'Ambrosio Katia , Limauro Danila , Pedone Emilia , Galdi Ilaria , Pedone Carlo , Bartolucci Simonetta , De Simone Giuseppina 
Published: February 2009

AbstractBcps constitute a group of antioxidant enzymes, belonging to the Prx family, that are widely distributed in bacteria, plants, and fungi. These proteins can contain two conserved cysteines within the CXXXXC motif. Recent studies demonstrated that though the role of the first cysteine is well defined, being the catalytic peroxidatic cysteine in all the members of this protein family, data on the function of the second cysteine are controversial and require further investigation. In this article, we report on the functional and structural characterization of Bcp1, an archaeal Bcp isolated from Sulfolobus solfataricus, which presents two conserved cysteine residues at positions 45 and 50. Functional studies revealed that this enzyme performs the catalytic reaction using an atypical 2‐Cys mechanism, where Cys45 is the peroxidatic and Cys50 is the resolving cysteine. The X‐ray structure of the double mutant C45S/C50S, representative of the fully reduced enzyme state, was determined at a resolution of 2.15 Å, showing a Trx fold similar to that of other Prxs. Superposition with a structural homologue in the oxidized state provided, for the first time, a detailed description of the structural rearrangement necessary for a member of the Bcp family to perform the catalytic reaction. From this structural analysis, it emerges that a significant conformational change from a fully folded, to a locally unfolded form is required to form the intramolecular disulfide bond upon oxidation, according to the proposed reaction mechanism. Two residues, namely Arg53 and Asp54, which could play a role in this rearrangement, were also identified. Proteins 2009. © 2009 Wiley‐Liss, Inc.
A practical guide to study directing
Authors: Brown Alan P. 
Published: February 2009

AbstractThe Good Laboratory Practice (GLP) regulations are designed to provide regulatory guidance and oversight of nonclinical studies that prospectively study the effects of test articles in test systems under laboratory conditions to determine their safety. These regulations are designed to assure quality, accountability, and reliability of safety data, and provide guidelines for improving the scientific validity of the studies. A key element of the GLP regulations is with respect to the role of the Study Director, who is the individual assigned as the single point of study control and has overall responsibility for the entire nonclinical study. Experience has shown that unless responsibility for the proper conduct of a study is assigned to a single individual, the potential exists for personnel to receive conflicting instructions, and for study events and issuance of the final report to occur in an uncoordinated fashion. While serving as the Study Director can be a challenging position with numerous demands and expectations, it is a role that allows an individual the opportunity to combine project management with technical and scientific skills in the pursuit of a single goal. Individuals who serve as Study Directors in the nonclinical laboratory typically represent a diverse range of educational and professional backgrounds, and oftentimes learn to become Study Directors on the job. The goal of this paper is to provide a concise description of the Study Director's responsibilities and give guidance for planning, initiating, and completing a nonclinical study. While this paper focuses on test articles that are evaluated in the pharmaceutical/biotechnology industry and regulated by the US Food and Drug Administration (FDA) GLPs, much of the information presented should apply to other GLP and non‐GLP studies. Copyright © 2009 John Wiley & Sons, Ltd.
The vertical structure of the lower Arctic troposphere analysed from observations and the ERA‐40 reanalysis
Authors: Tjernström Michael , Graversen Rune Grand 
Published: February 2009

AbstractIn situ atmospheric observations in the central Arctic are few and mostly from near the surface. A majority are from coastal regions whereas soundings over the Arctic Ocean are rare. This limits our understanding of the Arctic atmosphere, in particular aloft. It has been established that the vertical thermal structure is often stably stratified; this has been termed the ‘Arctic inversion’. It has also been established that near‐surface warming in the Arctic has been larger than the global mean warming during the last several decades. To estimate climate trends in this data‐sparse region, reanalysis data have often been used.In this paper we analyse the vertical thermal structure of the lower troposphere over the Arctic Ocean, using soundings from the SHEBA project. We find a strong annual cycle with strong surface inversions occurring only during autumn and winter, typically 500–800 metres deep and ∼10 °C strong. Summer is dominated by weaker elevated inversions at ∼100–400 m, a few hundred metres deep. Interestingly, this latter type of inversion also occurs frequently in winter, almost half the time. These soundings thus indicate that associating Arctic winter only with strong surface inversions is not entirely correct.We also compare these soundings to the ERA‐40 reanalysis data. Systematic biases in ERA‐40 in the SHEBA region include a near‐surface warm bias, on average ∼0.5–1.0 °C, and a slight mid‐troposphere cool bias. There is a significant difference in ERA‐40 performance statistics for the SHEBA year comparing with years without soundings for the same region. The analysis increment—a measure of the impact of the observations in the assimilation process—confirms this. For example, the assimilation of the SHEBA soundings reduces the near‐surface warm bias by about 50%. However, the overall vertical structure and its annual variation are surprisingly insensitive to the assimilation of the soundings, and are in fact well represented by ERA‐40. We speculate that the main improvement in assimilating the SHEBA soundings lies in an improvement in the timing of weather systems whereas their climatological vertical structure is less affected. Copyright © 2009 Royal Meteorological Society
Generic dealkylation: a tool for increasing the hit‐rate of metabolite rationalization, and automatic customization of mass defect filters
Authors: Mortishire‐Smith Russell J. , Castro‐Perez Jose M. , Yu Kate , Shockcor John P. , Goshawk Jeff , Hartshorn Mike J. , Hill Alastair 
Published: February 2009

AbstractThe use of exact mass liquid chromatography/mass spectrometry (LC/MS) for drug metabolism studies has increased significantly in recent years. Firstly, exact mass measurements facilitate identification of standard biotransformations through the use of narrow window extracted ion chromatograms, which are typically highly selective relative to signals from matrix or dosing components. Secondly, novel metabolites can be characterized via elemental formula calculations and high‐resolution product ion spectra. Furthermore, biological background ions can be removed by the use of mass defect filters (MDFs) which filter out ions based on the decimal component of their m/z value. Here, we describe an approach which we term ‘generic dealkylation’ that in association with other data interpretation tools adds significant value to the assignment process. Generic dealkylation uses a simple strategy to identify those bonds which have the potential to be cleaved by metabolism. In combination with standard phase 1 and phase 2 biotransformations, this allows creation of a chemically intelligent MDF which balances the need to remove matrix background with the requirement of avoiding filtering true metabolites. Secondly, generic dealkylation increases the hit‐rate at which non‐trivial (i.e. not covered by simple phase 1 oxidations or direct phase 2 conjugations) metabolites can be directly rationalized. The value of the generic dealkylation approach is illustrated by its application to determination of in vitro metabolic routes for two commercial drugs, nefazodone and indinavir. Copyright © 2009 John Wiley & Sons, Ltd.
Inter‐laboratory comparison of elemental analysis and gas chromatography/combustion/isotope ratio mass spectrometry. II. δ15N measurements of selected compounds for the development of an isotopic Grob test
Authors: Calderone Giovanni , Serra Francesca , Lees Michele , Mosandl Armin , Reniero Fabiano , Guillou Claude , Moreno‐Rojas José Manuel 
Published: February 2009

AbstractAn inter‐laboratory exercise was carried out by a consortium of five European laboratories to establish a set of compounds, suitable for calibrating gas chromatography/combustion/isotope ratio mass spectrometry (GC‐C‐IRMS) devices, to be used as isotopic reference materials for hydrogen, carbon, nitrogen and oxygen stable isotope measurements. The set of compounds was chosen with the aim of developing a mixture of reference materials to be used in analytical protocols to check for food and beverage authentication. The exercise was organized in several steps to achieve the certification level: the first step consisted of the a priori selection of chemical compounds on the basis of the scientific literature and successive GC tests to set the analytical conditions for each single compound and the mixture. After elimination of the compounds that turned out to be unsuitable in a multi‐compound mixture, some additional oxygen‐ and nitrogen‐containing substances were added to complete the range of calibration isotopes. The results of δ13C determinations for the entire set of reference compounds have previously been published, while the δD and δ18O determinations were unsuccessful and after statistical analysis of the data the results did not reach the level required for certification. In the present paper we present the results of an inter‐laboratory exercise to identify and test the set of nitrogen‐containing compounds present in the mixture developed for use as reference materials for the validation of GC‐C‐IRMS analyses in individual laboratories. Copyright © 2009 John Wiley & Sons, Ltd.
A new method for using 18O to trace ozone deposition
Authors: Subke Jens‐Arne , Toet Sylvia , D'Haese David , Crossman Zoe , Emberson Lisa D. , Barnes Jeremy D. , Ashmore Mike R. , Evershed Richard P. , Ineson Phil 
Published: February 2009

AbstractIsotopically labelled ozone (18O3) is an ideal tool to study the deposition of O3 to plants and soil, but no studies have made use of it due to the technical difficulties in producing isotopically enriched ozone. For 18O3 to be used in fumigation experiments, it has to be purified and stored safely prior to fumigations, to ensure that the label is present predominantly in the form of O3, and to make efficient use of isotopically highly enriched oxygen. We present a simple apparatus that allows for the safe generation, purification, storage, and release of 18O3. Following the purification and release of O3, about half (by volume) of the 18O is present in the form of O3. This means that for a given release of 18O3 into the fumigation system, a roughly identical volume of 18O2 is released. However, the small volume of this concurrent 18O2 release (100 nmol mol−1 in our experiment) results in only a minor shift of the much larger atmospheric oxygen pool, with no detectable consequence for the isotopic enrichment of either soil or plant materials. We demonstrate here the feasibility of using 18O as an isotopic tracer in O3 fumigations by exposing dry soil to 100 nmol mol−1 18O3 for periods ranging from 1 to 11 h. The 18O tracer accumulation in soil samples is measured using gas chromatography/isotope ratio mass spectrometry (GC/IRMS), and the results show a linear increase in 18O/16O isotope ratio over time, with significant differences detectable after 1 h of exposure. The apparatus is adapted for use with fumigation chambers sustaining flow rates of 1 m3 min−1 for up to 12 h, but simple modifications now allow larger quantities of O3 to be stored and continuously released (e.g. for use with open‐top chambers or FACE facilities). Copyright © 2009 John Wiley & Sons, Ltd.
Using Quick‐Start to enhance TCP‐friendly rate control performance in bidirectional satellite networks
Authors: Secchi Raffaello , Sathiaseelan Arjuna , Potortì Francesco , Gotta Alberto , Fairhurst Gorry 
Published: February 2009

AbstractIn the not so distant future, we envisage an Internet where the biggest share of capacity is used by streaming applications. To avoid congestion collapse from unresponsive flows calls for a robust and ubiquitous end‐to‐end multimedia congestion control mechanism, such as TCP‐friendly rate control (TFRC), which provides fair sharing with the other Internet traffic. This paper therefore analyses the implications of using rate‐adaptive congestion control over satellite links that utilize demand allocation multiple access (DAMA) to maximize satellite transponder utilization. The interaction between TFRC and DAMA is explored using simulations supported by fluidic flow models. The analysis shows that DAMA reduces the start‐up phase of TFRC, causing non‐negligible delays. To mitigate this problem, we propose a new cross‐layer method based on the Quick‐Start mechanism. This can accelerate the start‐up of multimedia flows by a judicious allocation of additional capacity derived from cross‐layer signalling. Copyright © 2009 John Wiley & Sons, Ltd.
Visualization of cellular DNA crosslinks by atomic force microscopy
Authors: Zhang Kun , Qi Hao , Li Hao , Liu Ying , Chen Wenfang 
Published: February 2009

AbstractCellular DNA crosslinks are a type of DNA damage induced by toxic chemicals or high‐energy radiation. If damaged DNA is not rapidly repaired, cells will die or mutate. To evaluate the types of DNA damage and their influence on vital cell activities, it is necessary to be able to detect DNA crosslinks. To date, indirect methods such as alkaline elution, potassium chloride–sodium dodecyl sulfate assay and comet assay have been used to detect DNA damage. Direct morphological observation, on the other hand, may be a useful tool to differentiate the types of DNA damage. In this report, atomic force microscopy (AFM) has been employed to visualize the breakage and crosslinking of cellular DNA strands in cells treated with formaldehyde and hydrogen peroxide. Our results showed that toxic chemical‐induced crosslinking of cellular DNA occurred in a dose‐dependent manner. DNA conglomerates were observed with high concentrations of formaldehyde, and the AFM observations were consistent with those of a comet assay. Our experiments demonstrate that AFM is an efficient method to differentiate the types of DNA damage. SCANNING 31: 75–82, 2009. © 2009 Wiley Periodicals, Inc.
Growth behavior of Cu/Al intermetallic compounds in hot‐dip aluminized copper
Authors: Yu Zhen , Duan Yuping , Liu Lidong , Liu Shunhua , Liu Xujing , Li Xiaogang 
Published: February 2009

AbstractHot‐dipped aluminum copper with plating auxiliary KF is introduced in this work. In this study, the intermetallic layer thickness varies with dipping temperature and time in a linear relationship. The main phases are identified to be CuAl2 and K3AlF6 by means of X‐ray diffraction. The reaction equations are deduced according to the elements concentration gradient in cross section. The copper diffusion rate in liquid Al is calculated to be 1.13 × 10−12 m2/s by Fick's second law in semi‐infinite solid model, and the obtained conductivity is 1.758–1.767 × 10−2 Ω mm2/m. The results indicate that the interfacial bonding is in a good state and plating auxiliary KF aqueous solution. can significantly improve the substrate wettability. The appropriate hot‐dipping condition for the samples is 953–973 K for 4–8 s. Copyright © 2009 John Wiley & Sons, Ltd.
Prenatal diagnosis of a novel mutation, c.529C>T (p.Q177X), in the BCKDHA gene in a family with maple syrup urine disease
Authors: Tammachote R. , Tongkobpetch S. , Desudchit T. , Suphapeetiporn K. , Shotelersuk V. 
Published: February 2009

SummaryMaple syrup urine disease (MSUD) is an autosomal recessive metabolic disorder caused by defective activity of the branched‐chain α‐keto‐acid dehydrogenase (BCKD) complex. The disease‐causing mutations can affect the BCKDHA, BCKDHB or DBT genes encoding for the E1a, E1b, and E2 subunits, respectively, of the BCKD complex. Here we report a girl who first presented to our clinic at 4 years of age with profound mental retardation. A diagnosis of MSUD was subsequently made based on the results of plasma amino acid analysis. Mutation analysis confirmed that she was homozygous for a novel mutation, c.529C>T (p.Q177X) in BCKDHA, while both parents, who were first cousins, were heterozygous. This enabled us to give an option of prenatal diagnosis to the parents. The prenatal testing for MSUD was performed during the mother's subsequent pregnancy and revealed that the fetus was heterozygous for the mutation. The healthy male neonate was born and his genotype was tested by restriction enzyme analysis, which confirmed the result of the prenatal testing. In summary, a late diagnosis of MSUD in patients without an unusual odour could occur especially in countries without neonatal screening programs as seen in the index patient. Mutation detection was, however, still beneficial to the family since prenatal testing could be performed in subsequent pregnancies. In addition, a novel mutation was found, expanding the mutation spectrum of this disease.
Perceived parenting styles, personality traits and sleep patterns in adolescents
Authors: Brand Serge , Hatzinger Martin , Beck Johannes , Holsboer‐Trachsler Edith 
Published: February 2009

ABSTRACTThe present study examined the role of parenting styles with respect to adolescents' sleep patterns and symptoms of depression and anxiety. A total of 246 adolescents (age: 17.58 ± 1.62) took part in the study. They completed several questionnaires with regard to parenting styles and to symptoms of anxiety and depression; additionally, they filled in a questionnaire assessing sleep‐related personality traits and completed a sleep log for 7 consecutive days. Results showed a high overlap between parenting styles of both parents, though with a different relation to adolescents' sleep. Adverse parenting styles were highly correlated with low sleep quality, negative mood, increased daytime sleepiness, and with increased symptoms of anxiety and depression. Adolescents with low positive and high negative parenting styles displayed the most unfavorable sleep‐related personality traits. Results suggest that parenting styles are related to young people's sleep pattern even at the beginning of late adolescence.
Quality discrimination for noxious stimuli in secondary somatosensory cortex: A MEG‐study
Authors: Maihöfner Christian , Kaltenhäuser Martin 
Published: February 2009

AbstractA complex cortical network is believed to encode the multi‐dimensionality of the human pain experience. In the present study, we used magnetoencephalography (MEG) to examine whether the cortical processing of noxious stimuli with different psychophysical properties differs in primary (S1) and secondary (S2) somatosensory cortices. Noxious low (condition 1) and high (condition 2) current density stimulations of equal stimulus intensities were applied at the left forearm in 12 subjects in a randomised order. Concomitantly, subjects had to evaluate the corresponding sensory‐discriminative and affective‐motivational pain dimensions. MEG revealed an increased activation of bilateral secondary somatosensory cortices (S2) during condition 2 compared to condition 1. Higher activations of bilateral S2 were significantly correlated with higher scores for the sensory‐discriminative component during condition 2. In contrast, corresponding scores for the affective‐motivational pain dimension did not differ between both conditions. Therefore, concerning the sensory dimension of the human pain experience we conclude that the S2 cortex is involved in the encoding of quality discrimination.
Effects of the copper intrauterine device on the expression of cyclooxygenase‐1 and ‐2 in the endometrium
Authors: Xin Zhi Min , Cao Lu Min , Xie Qin Zhen , Sun Yingpu , Su Ying Chun , Guo Yi Hong 
Published: February 2009

AbstractObjectiveTo examine the expression levels of cyclooxygenase (COX)‐1 and COX‐2 in the endometrium before and after insertion of the copper intrauterine device (Cu‐IUD).MethodsTen patients were investigated. Two endometrial biopsies were taken from the uterus of each patient. The first biopsy was taken prior to insertion of the Cu‐IUD, and the second was taken 1 month after insertion on the same day of the menstrual cycle and from the same location. The levels of COX‐1 and COX‐2 mRNA and protein in the endometrium were determined using reverse transcriptase polymerase chain reaction (RT‐PCR) and Western blotting.ResultsBefore insertion, expression of COX‐2 mRNA and proteins was 0.399 ± 0.014 and 14.75 ± 1.31, respectively. Post insertion, expression of COX‐2 mRNA and proteins was 0.563 ± 0.041 and 18.61 ± 1.93, respectively. A significant increase (P < 0.05) of COX between pre and post insertion of the Cu‐IUD was only seen with COX‐2. There was no significant change in the level of COX‐1 mRNA or proteins before and after insertion of the Cu‐IUD.ConclusionCOX‐2 is the primary isoenzyme stimulating overproduction of prostaglandins in the endometrium after the insertion of Cu‐IUDs.