bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rbp‐j regulates expansion of pancreatic epithelial cells and their differentiation into exocrine cells during mouse development
Authors: Fujikura Junji , Hosoda Kiminori , Kawaguchi Yoshiya , Noguchi Michio , Iwakura Hiroshi , Odori Shinji , Mori Eisaku , Tomita Tsutomu , Hirata Masakazu , Ebihara Ken , Masuzaki Hiroaki , Fukuda Akihisa , Furuyama Kenichiro , Tanigaki Kenji , Yabe Daisuke , Nakao Kazuwa 
Published: September 2007

AbstractNotch signaling regulates cell fate determination in various tissues. We have reported the generation of mice with a pancreas‐specific knockout of Rbp‐j using Pdx.cre mice. Those mice exhibited premature endocrine and ductal differentiation. We now generated mice in which the Rbp‐j gene was inactivated in Ptf1a‐expressing cells using Ptf1a.cre mice. The timing of the Cre‐mediated deletion in Rbp‐jf/f Ptf1a.cre mice is 1 day later than that in Rbp‐jf/f Pdx.cre mice. In Rbp‐jf/f Ptf1a.cre mouse pancreases, at E13.5, the reduced Hes1 expression was accompanied by reduced epithelial growth, but premature endocrine cell differentiation was minimal. At E15.5, Pdx1 expression was repressed and acinar cell differentiation was reduced, but an increase in acinar cell proliferation was observed during the perinatal period. Our study indicates that, in addition to its role in preventing premature differentiation of early endocrine cells, Rbp‐j regulates epithelial growth, Pdx1 expression, and acinar cell differentiation during mid‐pancreatic development. Developmental Dynamics 236:2779–2791, 2007. © 2007 Wiley‐Liss, Inc.
Dynamic expression of Thyrotropin‐releasing hormone in the mouse definitive endoderm
Authors: McKnight Kristen D. , Hou Juan , Hoodless Pamela A. 
Published: September 2007

AbstractThyrotropin‐releasing hormone (TRH) is a well‐characterized regulator of the hypothalamic–pituitary–thyroid endocrine axis. Here, we describe the expression of Trh during early embryonic development in the mouse. We find Trh to be highly expressed during postimplantation stages in the mouse embryo, with expression first observed in the epiblast at embryonic day (E) 6.5. During gastrulation, Trh is expressed in the newly formed definitive endoderm cells, and at embryonic day (E) 7.75, marks the entire definitive endoderm. Subsequently, Trh mRNA levels rapidly decrease such that, by E9.0, expression in the definitive endoderm is no longer detected, after which neural expression predominates. Thus, Trh is expressed dynamically and specifically in the developing mouse definitive endoderm from E7.0 to E8.5. Trh is unique among definitive endoderm markers as it transiently marks the entire definitive endoderm population and is not expressed in the extraembryonic endoderm. Trh will be a valuable tool to study definitive endoderm formation in the mouse embryo. Developmental Dynamics 236:2909–2917, 2007. © 2007 Wiley‐Liss, Inc.
On the Influence of “Arm‐on, Arm‐off” Processes on Alkene Hydrogenation Catalysed by a Rhodium Triphos Complex
Authors: Chaplin Adrian B. , Dyson Paul J. 
Published: September 2007

AbstractThe influence of phosphane “arm‐on, arm‐off” association/dissociation in rhodium catalysed alkene hydrogenation using [Rh(COD)(κ3‐triphos)]PF6 {1, COD = cyclooctadiene, triphos = 1,1,1‐tris(diphenylphosphanylmethyl)ethane} has been investigated by comparison of the activity of 1 to mixtures of the related diphosphane complex, [Rh(COD)(κ2‐dppp)]PF6 {2, dppp = 1,3‐bis(diphenylphosphanyl)propane} and triphenylphosphane (THF, 50 °C, 1 bar H2). These investigations are supplemented by a demonstration of the κ2–κ3 fluxionally of the triphos coordination in 1 by reversible reaction with [RuCl2(p‐cymene)]2 at room temperature in CH2Cl2. The product of this reaction, the bimetallic complex [(p‐cymene)Cl2Ru{(PPh2CH2)CMe(CH2PPh2)2}Rh(COD)]PF6, was isolated and fully characterized, including determination of the solid‐state structure by X‐ray diffraction analysis. Despite this evidence for facile arm‐off dissociation of the triphos ligand in 1, complex 2, with or without triphenylphosphane, was found to be more efficient for the hydrogenation of styrene and cyclohexene. Notably, use of triphenylphosphane together with 2 was found to have beneficial effects – increasing the rate of styrene hydrogenation (in some cases) and helping to stabilise the metal center during cyclohexene hydrogenation. These observations are supported by mercury poisoning experiments and reactivity experiments with 2 in medium pressure sapphire NMR tubes.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Ge6Me12 and Ge6H12 Cyclohexagermanes: Conformer Equilibria Studied by Raman Spectroscopy and Quantum Chemical Calculations
Authors: Hölbling Margit , Flock Michaela , Baumgartner Judith , Hassler Karl 
Published: September 2007

AbstractIn the first experimental study of rotational isomerism of a compound possessing a fourth row element backbone, the totally symmetric Ge–Ge stretching mode of dodecamethylcyclohexagermane (Ge6Me12), which is the most intense Raman band in the range 200–300 cm–1, was analyzed with temperature‐dependent vibrational Raman spectroscopy in both the crystalline and solution states. Below 50 °C, the Raman spectrum of the solid shows a single band at 232 cm–1 originating from the chair conformer. Between 50 and 60 °C, a shoulder at 227 cm–1 appears, which is associated with a twisted conformer. In solution, the band attributed to the chair conformer displays a shoulder arising from an averaged twist/boat conformer, even at –80 °C. The intensity of the shoulder increases with temperature. By using the van't Hoff relationship, an enthalpy difference of 2.4 kJ mol–1 between chair and twist/boat conformers was obtained. An improved X‐ray crystal structure of Ge6Me12 was also obtained, and an average Ge–Ge bond length of 242 pm was found, about 5 pm longer than previously reported. With the help of quantum chemical DFT and MP2 calculations, the geometries and energies of the conformers of Ge6Me12 and of the parent Ge6H12 compound were investigated thoroughly by employing 6‐31+G*, D95V and aug‐cc‐pVTZ basis sets, as well as SDD and aug‐cc‐pVTZ‐PP pseudopotentials on the Ge atoms. B3LYP/aug‐cc‐pVTZ calculations predict two conformers for Ge6H12, chair and twist, with zero‐point vibrational energy (ZPVE) corrected relative energies of 0.0 and 5.7 kJ mol–1, respectively. They predict three conformers, chair (0.0), twist (5.2) and boat (9.2), for Ge6Me12. They also give reasonable geometry parameters, relative energies and barriers for the conformer interconversion.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
The functional role of sphingomyelin in cell membranes
Authors: Slotte J. Peter , Ramstedt Bodil 
Published: September 2007

AbstractSphingomyelins (SM) constitute an important class of phospholipids in the membranes of most eukaryotic cells. In mammalian tissues, SM usually constitute 2–15% of the total organ phospholipid, but certain tissues such as brain, peripheral nervous tissue and ocular lenses have even higher SM contents. Typical properties of SM include their low degree of unsaturation, an asymmetric molecular structure, and their extensive hydrogen‐bonding properties. These features are all very important for the structural role of SM in biological membranes. SM interact favorably with cholesterol (and other sterols) and there is an established co‐localization of SM and cholesterol in the plasma membranes of cells and at the surface of lipoprotein particles. Together they form SM/sterol‐rich domains that often are more ordered than the surrounding phase in biological membranes. The growing body of evidence regarding their favorable interaction with sterols indicates that the functional role of SM per se is largely related to being a regulator of cholesterol distribution within cellular membranes and cholesterol homeostasis in cells. Together with other sphingolipids, SM also have an important functional role as precursors of sphingolipid signaling molecules, extensively reviewed elsewhere and not to be discussed here in more detail.
Comparison of extraction methods for determining tocopherols in soybeans
Authors: Lim Ho , Woo Sunhee , Kim Hong Sig , Jong Seung‐Keun , Lee Junsoo 
Published: September 2007

AbstractWe evaluated the usefulness of saponification, direct solvent extraction, and Soxhlet extraction as extraction methods to determine the amounts of tocopherols in soybeans. Soxhlet extraction yielded the highest analytical values for each tocopherol homolog and was the best method for quantifying tocopherols in soybeans. Coupling of simple Soxhlet extraction with HPLC provided a highly reproducible procedure to quantify tocopherols in soybeans. The percent mean recovery ± standard deviation (n = 5) was 103.2 ± 1.21, 109.8 ± 4.18, 93.8 ± 1.12, and 106.9 ± 1.54% for α‐, β‐, γ‐, and δ‐tocopherol, respectively. The linearity test for quantification was carried out over the ranges of 0.4–10.0, 0.2–4.0, 2.0–16.0, and 0.4–10.0 µg/mL for α‐, β‐, γ‐, and δ‐tocopherol, respectively. Regression analysis showed an excellent linear relationship (R2 >0.998), and the results of the validation parameters were generally reliable and satisfactory.
Sphingolipids in the gut? Which are the important issues?
Authors: Nilsson Åke 
Published: September 2007

AbstractGlycosphingolipids and sphingomyelin (SM) are important components of the apical brush border and the Golgi and endocytic vesicles of the gut epithelium. In particular, glucosylceramide is abundant in the microvilli. Synthesis and degradation of mucosal sphingolipids and targeting of sphingolipids to distinct cell compartments during cell differentiation are thus important features of intestinal lipid metabolism. Sphingolipids are also present in the ordinary Western diet, and sphingolipid‐rich formulations of dairy, plant or yeast origin are now available for studies of their biological effects in animals and humans. Since sphingolipids account for a large part of the polar lipids in milk, their digestion and effects in the suckling infant is of particular interest. Dietary sphingolipids are slowly digested and the exposure of the whole gut to sphingolipids and their metabolites can be increased by dietary supply. Metabolites from dietary sphingolipids may have anti‐inflammatory and anticarcinogenic effects and undigested sphingolipids may be protective. Dietary sphingolipids inhibit cholesterol absorption and may have beneficial metabolic effects. Some mucosal sphingolipids have blood group A, B and H reactivity and some act as receptors for bacterial toxins and virus. Sphingolipid signaling triggered by mucosal‐bacterial interaction may be important in both the gut and the bronchi.
Influence of the extraction process on dissolved oxygen in olive oil
Authors: Parenti Alessandro , Spugnoli Paolo , Masella Piernicola , Calamai Luca 
Published: September 2007

AbstractThe influence of the olive oil processing steps [paste malaxation (PM), decanter centrifugation (DC), and vertical centrifugation (VC)] on the dissolved oxygen (DO) concentration in virgin olive oil (VOO) right after production was investigated at industrial plant scale for two successive years. The influence of this parameter on quality decay during shelf life, assessed by peroxide value (PV) analysis, was also monitored. The VC step showed the higher oxygenation effect (50% increase in comparison to the control), and a good linear regression (r2 = 0.83) was found between the initial DO concentration and the PV after 2 days. An 18‐months shelf life test, performed on VOO sampled before and after the VC, indicated the slowest decay kinetics in the oils with the lower initial DO concentration, i.e. the non‐centrifuged oils.
Membrane phospholipids and sterols in microfiltered milk fat globules
Authors: Fauquant Caroline , Briard‐Bion Valérie , Leconte Nadine , Guichardant Michel , Michalski Marie‐Caroline 
Published: September 2007

AbstractNative milk fat globules of various mean diameters, ranging from d43 = 2.3 µm to 8.0 µm, were obtained using microfiltration of raw whole milk. After milk fat globule washing, the milk fat globule membrane (MFGM) was separated by manual churning. After total lipid extraction and separation of polar lipids, their phospholipid (PL) and sterol composition was measured using thin‐layer chromatography, methyl ester analyses by gas chromatography, and gas chromatography coupled to mass spectrometry. The main PL species were phosphatidylethanolamine, phosphatidylcholine and sphingomyelin. The respective fatty acid composition of each PL species was measured. Many different minor bioactive sterols were detected in the MFGM, e.g. lanosterol, lathosterol, desmosterol, stigmasterol and β‐sitosterol. No significant differences in the PL and sterol profile were found between MFGM extracted from small and large milk fat globule fractions.
The Use of Glycidol to Introduce Aldehyde Functions Into Proteins – Application to the Fluorescent Labelling of Bovine Serum Albumin and Avidin
Authors: Heldt Jan‐Martin , Fischer‐Durand Nathalie , Salmain Michèle , Vessières Anne , Jaouen Gérard 
Published: September 2007

AbstractThe reactions between 2,3‐epoxypropan‐1‐ol (glycidol) and either the nonglycosylated protein bovine serum albumin (BSA) or the glycoprotein avidin (AV) allowed the successful introduction of diol groups through the addition of some of the proteins' nucleophilic residues to the epoxide ring. The extent of glycolation could be readily tuned by varying the reaction time, the pH of reaction and the concentration of glycidol. Treatment of the stable protein‐diol intermediates with sodium periodate resulted in the generation of reactive aldehyde functionalities through the oxidation of the glycol moieties. At this step, the amount of generated aldehydes could also be modulated by changing the time and/or pH of oxidation. As an application, both formylated proteins were successfully labelled with the hydrazide‐containing fluorescent dye Lucifer Yellow CH (LyCH), affording highly fluorescent conjugates. Mild oxidation of the avidin‐diol left untouched glycol moieties that contributed to greatly enhance water solubility in the avidin‐LyCH bioconjugates. In certain cases the avidin‐LyCH conjugates retained a good affinity for biotin, as shown in a competitive binding assay. Glycidol thus appears to be an attractive low‐cost reagent for protein chemical activation aimed at further coupling of amine‐containing species.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Palladium‐Catalyzed Carbonylation of 2‐Haloselenophenes: Synthesis of Selenophene‐2‐carboxamides, Selenophene‐2,5‐dicarboxamides and N,N′‐Bridged Selenophene‐2‐carboxamides
Authors: Prediger Patrícia , Brandão Ricardo , Nogueira Cristina W. , Zeni Gilson 
Published: September 2007

AbstractWe present herein our results on the palladium‐catalyzed carbonylation of 2‐haloselenophene and amines, under carbon monoxide atmosphere, giving a new route to prepare selenophene‐2‐carboxamides, selenophene‐2,5‐dicarboxamides and N,N′‐bridged selenophene‐2‐carboxamides in good yields. The reaction proceeded cleanly under mild conditions, using a simple apparatus and procedure, and in the absence of high pressure of carbon monoxide. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Polyphenothiazine Modified Electrochemical Aptasensor for Detection of Human α‐Thrombin
Authors: Porfirieva Anna , Evtugyn Gennady , Hianik Tibor 
Published: September 2007

AbstractQCM aptasensor for detection human thrombin has been developed on the base of polymeric forms of phenothiazine dyes, Methylene Blue and Methylene Green. Electrostatic accumulation of the analyte in the polyphenothiazine layer made it possible to increase the sensitivity of QCM detection of thrombin in comparison with bare gold electrodes coated with avidin or neutravidin. The influence of nonspecific binding of human serum albumin and the optimal composition of the surface layers were determined. The aptasensors developed make it possible to detect 10–100 nM of thrombin.
Standardless Electrochemical Method for Mercury, Cadmium, Lead and Copper Determination in Aqueous Solution
Authors: Sheremet Anastasiya , Averyaskina Elena , Chekmeneva Elena , Ermakov Sergey 
Published: September 2007

AbstractA standardless electrochemical method for metal ion determination in aqueous solution is proposed. This method is based on the combination of stripping voltammetry and controlled potential coulometry laws. Its application requires neither calibration using standard solutions nor standard additions to the studying solutions. The efficiency of the new method was examined using the detection of mercury, cadmium, copper and lead ions in aqueous media. The interference of metal ions was studied, and the determination of each metal ion was carried out in the presence of the others. The method was tested on samples of river water analyzed independently by atomic absorption spectrometry. A good agreement of the results was demonstrated.
Sensitive fluorescence detection of polyphosphate in polyacrylamide gels using 4′,6‐diamidino‐2‐phenylindol
Authors: Smith Stephanie A. , Morrissey James H. 
Published: September 2007

AbstractPAGE is commonly used to identify and resolve inorganic polyphosphates (polyP). We now report highly sensitive and specific staining methods for polyP in polyacrylamide gels based on the fluorescent dye, 4′,6‐diamidino‐2‐phenylindol (DAPI). DAPI bound to polyP in gels fluoresced yellow while DAPI bound to nucleic acids or glycosaminoglycans fluoresced blue. Inclusion of EDTA prevented staining of glycosaminoglycans by DAPI. We also identified conditions under which DAPI that was bound to polyP (but not nucleic acids or other anionic polymers) rapidly photobleached. This allowed us to develop an even more sensitive and specific negative staining method that distinguishes polyP from nucleic acids and glycosaminoglycans. The lower LOD using DAPI negative staining was 4 pmol (0.3 ng) phosphate per band, compared to conventional toluidine blue staining with a lower LOD of 250 pmol per band.
A fast CE method for the achiral separation of methadone and its major metabolites, 2‐ethylidene‐1,5‐dimethyl‐3,3‐diphenylpyrrolidine and 2‐ethyl‐5‐methyl‐3,3‐diphenyl‐1‐pyrroline
Authors: Kelly Tamsin , Doble Philip , Dawson Michael 
Published: September 2007

AbstractThe utilization of dynamic doubly coated capillaries for a fast separation of methadone and its two major metabolites, 2‐ethylidene‐1,5‐dimethyl‐3,3‐diphenylpyrrolidine (EDDP) and 2‐ethyl‐5‐methyl‐3,3‐diphenyl‐1‐pyrroline (EMDP) was investigated. The coated capillaries were prepared using a polycation of poly(diallyldimethylammonium chloride) and a polyanion of dextran sulfate. A fast achiral separation was developed using the coated capillaries with a BGE of 100 mM phosphate buffer at pH 2.6. Complete achiral separation of methadone, EDDP and EMDP was achieved, with migration times of approximately 4 min. The method offers considerable advantages with respect to BGE simplicity and analysis time compared to previously published CE methods for methadone and its related analytes.
A generalized time‐effect factor model and its application: recovering trend of temperature by pollen data
Authors: Hu Yu‐Pin , Chou Rouh‐Jane 
Published: September 2007

AbstractIn order to extract the time‐effect factors of multiple time series, a generalized time‐effect factor model (GTFM) and a statistic for identifying the model are proposed. This model is a general form of the Peña‐Box model. Based on the model, a pollen data set from Taiwan is analyzed. A factor, named temperature, is extracted. Its trend is then used to recover the weather of Taiwan over the past 5000 years. Copyright © 2007 John Wiley & Sons, Ltd.
Spatial prediction of river channel topography by kriging
Authors: Legleiter Carl J. , Kyriakidis Phaedon C. 
Published: September 2007

AbstractTopographic information is fundamental to geomorphic inquiry, and spatial prediction of bed elevation from irregular survey data is an important component of many reach‐scale studies. Kriging is a geostatistical technique for obtaining these predictions along with measures of their reliability, and this paper outlines a specialized framework intended for application to river channels. Our modular approach includes an algorithm for transforming the coordinates of data and prediction locations to a channel‐centered coordinate system, several different methods of representing the trend component of topographic variation and search strategies that incorporate geomorphic information to determine which survey data are used to make a prediction at a specific location. For example, a relationship between curvature and the lateral position of maximum depth can be used to include cross‐sectional asymmetry in a two‐dimensional trend surface model, and topographic breaklines can be used to restrict which data are retained in a local neighborhood around each prediction location. Using survey data from a restored gravel‐bed river, we demonstrate how transformation to the channel‐centered coordinate system facilitates interpretation of the variogram, a statistical model of reach‐scale spatial structure used in kriging, and how the choice of a trend model affects the variogram of the residuals from that trend. Similarly, we show how decomposing kriging predictions into their trend and residual components can yield useful information on channel morphology. Cross‐validation analyses involving different data configurations and kriging variants indicate that kriging is quite robust and that survey density is the primary control on the accuracy of bed elevation predictions. The root mean‐square error of these predictions is directly proportional to the spacing between surveyed cross‐sections, even in a reconfigured channel with a relatively simple morphology; sophisticated methods of spatial prediction are no substitute for field data. Copyright © 2007 John Wiley & Sons, Ltd.
Modeling fluvial response to in‐stream woody vegetation: implications for stream corridor restoration
Authors: Bennett Sean J. , Wu Weiming , Alonso Carlos V. , Wang Sam S. Y. 
Published: September 2007

AbstractRiver restoration and bank stabilization programs often use vegetation for improving stream corridor habitat, aesthetic and function. Yet no study has examined the use of managed vegetation plantings to transform a straight, degraded stream corridor into an ecologically functional meandering channel. Experimental data collected using a distorted Froude‐scaled flume analysis show that channel expansion and widening, thalweg meandering and riffle and pool development are possible using discrete plantings of rigid, emergent vegetation, and the magnitudes of these adjustments depend on the shape of the vegetation zone and the density of the vegetation. These experimental results were verified and validated using a recently developed numerical model, and model output was then used to discuss mechanistically how rivers respond to the introduction of in‐stream woody vegetation. Finally, a hybrid method of meander design is proposed herein where managed vegetation plantings are used to trigger or force the desired morphologic response, transforming a straight, degraded reach into a more functional meandering corridor. It is envisioned that such numerical models could become the primary tool for designing future stream restoration programs involving vegetation and assessing the long‐term stability of such activities. Copyright © 2007 John Wiley & Sons, Ltd.