bluuebunny/crossref_metadata_2025_split huggingface dataset:
Refinement of a morphological scoring system for postimplantation rabbit conceptuses
Authors: Carney Edward W. , Tornesi Belen , Keller Charles , Findlay Heather A. , Nowland William S. , Marshall Valerie A. , Ozolinš Terence R.S. 
Published: June 2007

AbstractBACKGROUND:The rabbit is used extensively in developmental toxicity testing, yet basic information on rabbit embryo development is lacking. The goals of this study were to refine a rabbit embryo morphology scoring system, and use it to evaluate rabbit whole embryo cultures (WEC).METHODS:A total of 265 conceptuses were harvested between GD 8.0 and 12.0 (coitus = GD 0) at 6‐hr intervals and examined in detail. Discreet developmental landmarks were then established for 18 morphological features and assigned scores ranging from 0 up to 6. The scoring system was then validated on a subset of randomly selected in vivo conceptuses, and was used to evaluate conceptuses grown for 12, 24, 36, or 48 hr in WEC beginning from GD 9.0 or 10.0. A few embryos also were examined using microscopic computed tomography (microCT)‐based virtual histology™ to assess the utility of this technology.RESULTS:Morphology scores of in vivo developed conceptuses increased linearly (r2= 0.98) with advancing gestational age, from means of 0.0 on GD 8.0 to 67.9 on GD 12.0. Application of the scoring system, supplemented with evidence from Virtual histology™, indicated that the WEC system supported normal morphological development of rabbit conceptuses. However, when explanted at GD 9, the rate of development was about 20% slower than in vivo, whereas the rate of development in WEC from GD 10 was indistinguishable from in vivo.CONCLUSIONS:This work enhances the evaluation tools available to study mechanisms of normal and abnormal development in this widely used animal testing species.Birth Defects Res (Part B), 2007. © 2007 Wiley‐Liss, Inc.
Estrous cycle‐dependent histology and review of sex steroid receptor expression in dog reproductive tissues and mammary gland and associated hormone levels
Authors: Rehm Sabine , Stanislaus Dinesh J. , Williams Ann M. 
Published: June 2007

AbstractThis report describes normal histology of tissues from immature female dogs and sequential microscopic changes that occur during different stages of the estrous cycle in ovary, uterus, vagina and mammary glands. These observations are associated with a literature review of concurrent estrous cycle plasma hormone levels and expression of sex steroid receptors in these tissues. The combined review of different aspects of the estrous cycle in the dog provides readers with a comprehensive presentation and may guide investigators that are involved in testing compounds with hormonal effects in female dogs. Birth Defects Res (Part B), 2007. © 2007 Wiley‐Liss, Inc.
Development and evaluation of intermediate frequency magnetic field exposure system for studies of in vitro biological effects
Authors: Fujita Atsushi , Hirota Izuo , Kawahara Yoshinobu , Omori Hideki 
Published: June 2007

AbstractWe have developed an intermediate frequency (IF) magnetic field exposure system for in vitro studies. Since there are no previous studies on exposure to heating‐frequency magnetic fields generated from an induction heating (IH) cook top, there is a strong need for such an exposure system and for biological studies of IF magnetic fields. This system mainly consists of a magnetic‐field‐generating coil housed inside an incubator, inside which cultured cells can be exposed to magnetic field. Two systems were prepared to allow the experiment to be conducted in a double‐blind manner. The level of the generated magnetic field was set to 532 µTrms in the exposure space, 23 kHz, 80 times the value in the International Commission on Non‐ionizing Radiation Protection (ICNIRP) guidelines, with a spatial field uniformity better than 3.8%. The waveforms were nearly sinusoidal. It was also confirmed that the parasitic electric field was 157 V/mrms and the induced electric field was 1.9 V/mrms. The temperature was maintained at 36.5 ± 0.5 °C for 2 h. Furthermore, leaked magnetic flux density was 0.7 µTrms or lower at extremely low frequency (ELF) and IF in the stopped system when the other system was being operated, and the environmental magnetic flux density was 0.1 µTrms or lower at the center of the coils. As a result, it was confirmed that this system could be successfully used to evaluate the biological effects of exposure to IF magnetic fields. Bioelectromagnetics 28:538–545, 2007. © 2007 Wiley‐Liss, Inc.
Eine gelernte Lebensweise: Figurationen des Gelehrtenlebens zwischen Mittelalter und Früher Neuzeit
Authors: Algazi Gadi 
Published: June 2007

AbstractA Learned Way of Life: Figurations of Scholarly Life between the Middle Ages and the Early Modern Period. – With the erosion of professors' obligatory celibacy in northwestern European universities of the high Middle Ages, scholars found themselves facing the task of redefining their mode of life and establishing a new type of families, combining social reproduction and the transmission of academic knowledge, and adopting daily habits and dispositions which would allow them to lead the life of the mind within crowded family households without the collective discipline and material infrastructure provided by communal institutions, such as colleges. Building on the author's earlier work, the paper sketches a synthetic view of the major elements of the scholars' emerging way of life, arguing that this transformation provides a unique opportunity for studying how a way of life takes shape, being explicitly discussed and experimented with. Shaping a rational, or rather systematically rationalized way of life, it is argued, is a major contribution of the scientific tradition to making modern cultures.
A New Proposal for Multivariable Modelling of Time‐Varying Effects in Survival Data Based on Fractional Polynomial Time‐Transformation
Authors: Sauerbrei Willi , Royston Patrick , Look Maxime 
Published: June 2007

AbstractThe Cox proportional hazards model has become the standard for the analysis of survival time data in cancer and other chronic diseases. In most studies, proportional hazards (PH) are assumed for covariate effects. With long‐term follow‐up, the PH assumption may be violated, leading to poor model fit. To accommodate non‐PH effects, we introduce a new procedure, MFPT, an extension of the multivariable fractional polynomial (MFP) approach, to do the following: (1) select influential variables; (2) determine a sensible dose‐response function for continuous variables; (3) investigate time‐varying effects; (4) model such time‐varying effects on a continuous scale. Assuming PH initially, we start with a detailed model‐building step, including a search for possible non‐linear functions for continuous covariates. Sometimes a variable with a strong short‐term effect may appear weak or non‐influential if ‘averaged’ over time under the PH assumption. To protect against omitting such variables, we repeat the analysis over a restricted time‐interval. Any additional prognostic variables identified by this second analysis are added to create our final time‐fixed multivariable model. Using a forward‐selection algorithm we search for possible improvements in fit by adding time‐varying covariates. The first part to create a final time‐fixed model does not require the use of MFP. A model may be given from ‘outside’ or a different strategy may be preferred for this part. This broadens the scope of the time‐varying part. To motivate and illustrate the methodology, we create prognostic models from a large database of patients with primary breast cancer. Non‐linear time‐fixed effects are found for progesterone receptor status and number of positive lymph nodes. Highly statistically significant time‐varying effects are present for progesterone receptor status and tumour size. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Testing Approaches for Overdispersion in Poisson Regression versus the Generalized Poisson Model
Authors: Yang Zhao , Hardin James W. , Addy Cheryl L. , Vuong Quang H. 
Published: June 2007

AbstractOverdispersion is a common phenomenon in Poisson modeling, and the negative binomial (NB) model is frequently used to account for overdispersion. Testing approaches (Wald test, likelihood ratio test (LRT), and score test) for overdispersion in the Poisson regression versus the NB model are available. Because the generalized Poisson (GP) model is similar to the NB model, we consider the former as an alternate model for overdispersed count data. The score test has an advantage over the LRT and the Wald test in that the score test only requires that the parameter of interest be estimated under the null hypothesis. This paper proposes a score test for overdispersion based on the GP model and compares the power of the test with the LRT and Wald tests. A simulation study indicates the score test based on asymptotic standard Normal distribution is more appropriate in practical application for higher empirical power, however, it underestimates the nominal significance level, especially in small sample situations, and examples illustrate the results of comparing the candidate tests between the Poisson and GP models. A bootstrap test is also proposed to adjust the underestimation of nominal level in the score statistic when the sample size is small. The simulation study indicates the bootstrap test has significance level closer to nominal size and has uniformly greater power than the score test based on asymptotic standard Normal distribution. From a practical perspective, we suggest that, if the score test gives even a weak indication that the Poisson model is inappropriate, say at the 0.10 significance level, we advise the more accurate bootstrap procedure as a better test for comparing whether the GP model is more appropriate than Poisson model. Finally, the Vuong test is illustrated to choose between GP and NB2 models for the same dataset. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fatty acids decrease catalase activity in human leukaemia cell lines
Authors: Azevedo‐Martins Anna K. , Curi R. 
Published: June 2007

AbstractFatty acid (FA) may disturb the redox state of the cells not only by an increase in reactive oxygen species (ROS) generation but also due to a reduction in antioxidant enzyme activities. The effect of various FAs (palmitic, stearic, oleic, linoleic, γ‐linolenic and eicosapentaenoic acids (EPAs)) on Jurkat and Raji cells, (human T and B leukaemic cell lines was investigated). The following measurements were carried out: FA composition of the cells, cell proliferation and activities of catalase, glutathione peroxidase (GPx) and superoxide dismutase (SOD). The protective effect of α‐tocopherol on cell death was also investigated. Each cell line presented a specific FA composition. All the tested FAs reduced catalase activity. The toxic effect of FA was abolished by the pre‐incubation with physiological concentrations of α‐tocopherol. The findings support the proposition that the increase in oxidative stress induced by FA partially occurs due to a reduction in catalase activity. In spite of the decrease in the enzyme activity, catalase protein and mRNA levels were not changed, suggesting a post‐translational regulation. Copyright © 2007 John Wiley & Sons, Ltd.
Copper(II) Interaction with Prion Peptide Fragments Encompassing Histidine Residues Within and Outside the Octarepeat Domain: Speciation, Stability Constants and Binding Details
Authors: Ősz Katalin , Nagy Zoltán , Pappalardo Giuseppe , Di Natale Giuseppe , Sanna Daniele , Micera Giovanni , Rizzarelli Enrico , Sóvágó Imre 
Published: June 2007

AbstractA 31‐mer polypeptide, which encompasses residues 84–114 of human prion protein HuPrP(84–114) and contains three histidyl residues, namely one from the octarepeat (His85) and two histidyl residues from outside the octarepeat region (His96 and His111), and its mutants with two histidyl residues HuPrP(84–114)His85Ala, HuPrP(84–114) His96Ala, HuPrP(84–114)His111Ala and HuPrP(91–115) have been synthesised and their Cu2+ complexes studied by potentiometric and spectroscopic (UV/Vis, CD, EPR, ESI‐MS) techniques. The results revealed a high Cu2+‐binding affinity of all peptides, and the spectroscopic studies made it possible to clarify the coordination mode of the peptides in the different complex species. The imidazole nitrogen donor atoms of histidyl residues are the exclusive metal‐binding sites below pH 5.5, and they have a preference for macrochelate structure formation. The deprotonation and metal‐ion coordination of amide functions take place by increasing the pH; all of the histidines can be considered to be independent metal‐binding sites in these species. As a consequence, di‐ and trinuclear complexes can be present even in equimolar samples of the metal ion and peptides, but the ratios of polynuclear species do not exceed the statistically expected ones; this excludes the possibility of cooperative Cu2+ binding. The species with a (Nim,N,N)‐binding mode are favoured around pH 7, and their stability is enhanced by the macrochelation from another histidyl residue in the mononuclear complexes. The independence of the histidyl sites results in the existence of coordination isomers and the preference for metal binding follows the order of: His111>His96>His85. Deprotonation and metal‐ion coordination of the third amide functions were detected in slightly alkaline solutions at each of the metal‐binding sites; all had a (Nim,N,N,N)‐coordination mode. Spectroscopic measurements also made it clear that the four lysyl amino groups of the peptides are not metal‐binding sites in any cases.
Discotic Liquid‐Crystalline Materials Based on Porphycenes: A Mesogenic Metalloporphycene–Tetracyanoquinodimethane (TCNQ) Adduct
Authors: Stępień Marcin , Donnio Bertrand , Sessler Jonathan L. 
Published: June 2007

AbstractA number of substituted zinc(II) porphycenes and porphyrins have been synthesized as potentially mesogenic materials. One of the resulting porphycenes, bearing eight decyloxy chains, exhibits two mesophases, a transient lamellar phase (Lam) and a highly ordered lamello‐columnar phase (LCol), with remarkably different structural characteristics. The same zinc(II) porphycene also forms an electron donor–acceptor (EDA) complex with tetracyanoquinodimethane (TCNQ), generating a hexagonal columnar mesophase (Colh) that is thermally stable up to ca. 200 °C. The EDA interaction between porphycene and TCNQ has been probed using electronic and vibrational spectroscopy. A mixture of zinc(II) porphyrins, isomeric with the above porphycene complex, forms a rectangular columnar mesophase (Colr).
A Comparative Study on Absorption and Selectivity of Organic Vapors by Using Ionic Liquids Based on Imidazolium, Quaternary Ammonium, and Guanidinium Cations
Authors: Kulkarni Prashant S. , Branco Luís C. , Crespo João G. , Afonso Carlos A. M. 
Published: June 2007

AbstractA novel study on organic solute absorption from the vapor phase is reported. The organic solutes chosen for the absorption studies include 1,4‐benzodioxane, biphenyl, xanthene, and menthol. A series of imidazolium, ammonium, and guanidinium‐based ionic liquids (ILs) containing several types of anions were used as absorbents. Absorption of water vapor was also studied along with the organic solutes. Absorption studies of each organic solute were performed by using a specially devised glass apparatus at 50 °C. It was observed that the rate of absorption increases with time and is faster in the case of 1,4‐benzodioxane (24 h). The absorption process for each organic solute with different classes of ionic liquids was studied and the results were compared with each other. Absorption values of more than 25 000 ppm were observed in some ionic liquids. Distribution ratios of organic solutes in an ionic liquid and in the vapor phase were measured and the selectivity was evaluated by using the distribution ratio values. A remarkable selectivity was observed for some ionic liquids towards a specific organic solute. Importantly, it was observed that the selectivity remained constant, even though a mixture of solute was used for the absorption study. Desorption of organic vapors from ionic liquids was successfully carried out by applying a vacuum. Further, it was observed that the same ionic liquid can be repeatedly reused several times for absorption. These studies reveal that, in future, a task‐specific ionic liquid can be prepared and used for specific solute capture from the vapor phase.
Do Photolyases Need To Provide Considerable Activation Energy for the Splitting of Cyclobutane Pyrimidine Dimer Radical Anions?
Authors: Song Qin‐Hua , Tang Wen‐Jian , Ji Xue‐Bao , Wang Hong‐Bo , Guo Qing‐Xiang 
Published: June 2007

Abstractcis–syn Cyclobutane pyrimidine dimers, major UV‐induced DNA lesions, are efficiently repaired by DNA photolyases. The key step of the repair reaction is a light‐driven electron transfer from the FADH− cofactor to the dimer; the resulting radical anion splits spontaneously. Whether the splitting reaction requires considerable activation energy is still under dispute. Recent reports show that the splitting reaction of a dimer radical anion has a significant activation barrier (0.45 eV), and so photolyases have to provide considerable energy. However, these results contradict observations that cis–syn dimer radical anions split into monomers at −196 °C, and that the full process of DNA photoreactivation was fast (1.5–2 ns). To investigate the activation energies of dimer radical anions, three model compounds 1–3 were prepared. These include a covalently linked cyclobutane thymine dimer and a tryptophan residue (1) or a flavin unit (3), and the covalently linked uracil dimer and tryptophan (2). Their properties of photosensitised splitting of the dimer units by tryptophan or flavin unit were investigated over a large temperature range, −196 to 70 °C. The activation energies were obtained from the temperature dependency of splitting reactions for 1 and 2, 1.9 kJ mol−1 and 0.9 kJ mol−1 for the thymine and uracil dimer radical anions, respectively. These values are much lower than that obtained for E. coli photolyase (0.45 eV), and are surmountable at −196 °C. The activation energies provide support for previous observations that repair efficiencies for uracil dimers are higher than thymine dimers, both in enzymatic and model systems. The mechanisms of highly efficient enzymatic DNA repair are discussed.
Synthesis, X‐ray Diffraction and Computational Study of the Crystal Packing of Polycyclic Hydrocarbons Featuring Aromatic and Perfluoroaromatic Rings Condensed in the Same Molecule: 1,2,3,4‐Tetrafluoronaphthalene, ‐anthracene and ‐phenanthrene
Authors: Cozzi Franco , Bacchi Sergio , Filippini Giuseppe , Pilati Tullio , Gavezzotti Angelo 
Published: June 2007

AbstractWe have synthesised some planar polycyclic compounds, in which unsubstituted aromatic rings are condensed with perfluorinated aromatic rings, and have carried out a combined X‐ray diffraction and computational study to analyse their self‐recognition behaviour in crystalline phases. We compare our results with the parent hydrocarbons and with other compounds that have a variable degree of fluorination. Whereas the molecular planes in crystals of hydrocarbons with mono‐ or difluorinated aromatic rings or of perfluorinated compounds arrange themselves in V‐shaped configurations, our present results show that perfluorinated rings tend to stack over unsubstituted rings even when these two moieties coexist in a condensed system, producing crystalline materials with parallel molecular layers with the arene–perfluoroarene recognition pattern. Our analysis shows that the packing energy of all these crystals is dispersion‐dominated and that coulombic terms are selective rather than quantitatively predominant in crystals with arene–perfluoroarene interactions. No compelling proof of a special role of CH⋅⋅⋅F interactions has been found.
Variation of Heterometallic Structural Motifs Based on [W(CN)8]3− Anions and MnII Ions as a Function of Synthetic Conditions
Authors: Zhao Hanhua , Shatruk Mikhail , Prosvirin Andrey V. , Dunbar Kim R. 
Published: June 2007

AbstractReactions of [W(CN)8]3−/4− anions with complexes of Mn2+ ion with tridentate organic ligand 2,4,6‐tris(2‐pyridyl)‐1,3,5‐triazine (tptz) lead to a series of heterobimetallic complexes. The crystal structures of these compounds are derived from the same basic structural fragment, namely a W2Mn2 square constructed of alternating cyanide‐bridged W and Mn ions. In [MnII(tptz)(OAc)(H2O)2]2{[MnII(tptz)(MeOH)1.58(H2O)0.42]2[WV(CN)8]2}⋅5 MeOH⋅9.85 H2O (3), isolated molecular squares are co‐crystallized with mononuclear cationic MnII complexes. The structure of {[MnII(tptz)(MeOH)]2[WIV(CN)8]⋅2 MeOH}∞ (4) is based on an infinite chain of vertex‐sharing squares, while {[MnII2(tptz)2(MeOH)3(OAc)][WV(CN)8]⋅3.5 MeOH⋅0.25 H2O}∞ (5) and {[MnII2(tptz)2(MeOH)3WV(CN)8][MnII(tptz)(MeOH)WV(CN)8] ⋅2 H2O⋅MeOH}8 (7) are derived from such an infinite chain by removing one of the W‐CN‐Mn linkages in each of the squares. The decanuclear cluster [MnII6(tptz)6(MeOH)4(DMF)2WV4(CN)32]⋅8.2 H2O⋅2.3 MeOH (6) is a truncated version of structure 4 and consists of three vertex‐sharing W2Mn2 squares. The structure of [MnII(tptz)(MeOH)(NO3)]2[MnII(tptz)(MeOH) (DMF)]2[WV(CN)8]2⋅6 MeOH (8) consists of a hexanuclear cluster, in which the central W2Mn2 square is extended by two Mn side‐arms attached via CN− ligands to the W corners of the square. The magnetic behavior of these heterobimetallic complexes (except for 4) is dominated by antiferromagnetic coupling between MnII and WV ions mediated by cyanide bridges. Compounds 3, 6, and 8 exhibit high spin ground states of S=4, 13, and 9, respectively, while 5 and 7 exhibit behavior typical of a ferrimagnetic chain with alternating spin centers. Complex 4 contains diamagnetic WIV centers but holds promise as a potential photomagnetic solid.
Ab initio Study of Structure and Stability of M2Al2 (M: Cu, Ag, and Au) Clusters
Authors: Liu FengLi , Zhao YongFang , Li XinYing , Hao FengYou 
Published: June 2007

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
A First‐Principles Study of the Electronic and Structural Properties of γ‐TaON.
Authors: Wolff Holger , Bredow Thomas , Lerch Martin , Schilling Heikko , Irran Elisabeth , Stork Alexandra , Dronskowski Richard 
Published: June 2007

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
The High‐Temperature Phases HT‐YPtSn, HT‐GdPtSn, and HT‐TbPtSn.
Authors: Riecken Jan Freerks , Heymann Gunter , Huppertz Hubert , Poettgen Rainer 
Published: June 2007

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Textural and Capacitive Characteristics of Hydrothermally Derived RuO2×xH2O Nanocrystallites: Independent Control of Crystal Size and Water Content.
Authors: Chang Kuo‐Hsin , Hu Chi‐Chang , Chou Chih‐Yin 
Published: June 2007

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
The Magnetic Structure of Mn2GeSe4.
Authors: Mikus Holger , Deiseroth Hans‐Joerg , Aleksandrov Krassimir , Ritter Clemens , Kremer Reinhard K. 
Published: June 2007

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.