bluuebunny/crossref_metadata_2025 huggingface dataset:
Zone‐specific remodeling of tumor blood vessels affects tumor growth
Authors: Tilki Derya , Kilic Nerbil , Sevinc Sema , Zywietz Friedrich , Stief Christian G. , Ergun Suleyman
Published: September 2007

BACKGROUND.

Chaotic organization, abnormal leakiness, and structural instability are characteristics of tumor vessels. However, morphologic events of vascular remodeling in relation to tumor growth are not sufficiently studied yet.

METHODS.

By using the rat rhabdomyosarcoma tumor model vascular morphogenesis was studied by light and electron microscopy and immunohistochemistry in relation to tumor regions such as tumor surrounding (TSZ), marginal (TMZ), intermediate (TIZ), and center (TCZ) zones.

RESULTS.

The analyses revealed that blood vessels of TSZ display a regular ultrastructure, whereas blood vessels of TMZ showed a chaotic organization and unstable structure with a diffuse or even lacking basal lamina, and missing or irregular assembled periendothelial cells. In contrast, blood vessels of TIZ and TCZ exhibited a more or less stabilized vessel structure with increased diameter. Correspondingly, normal assembly of α‐smooth‐muscle‐actin (α‐SMA)‐positive cells into the vessel wall was observed in blood vessels of TSZ, TIZ, and TCZ. Also, Ang1 immunostaining was strongest in large vessels of TIZ and TCZ, whereas Ang2 staining was prominent in small vessels of TIZ. Tie2 staining was detectable in small and large vessels of all tumor zones. Immunostaining for αvβ3‐integrin was strongest in small vessels of TMZ, whereas large vessels of TIZ and TCZ were almost negative.

CONCLUSIONS.

The results indicate a zone‐specific remodeling of tumor blood vessels by stabilization of vessels in TIZ and TCZ, whereas small vessels of these zones obviously undergo regression leading to tumor necrosis. Thus, a better understanding of vascular remodeling and stabilization in tumors would enable new strategies in tumor therapy and imaging. Cancer 2007. © 2007 American Cancer Society.
Reproductive history, infertility treatment, and the risk of acute leukemia in children with down syndrome
Authors: Puumala Susan E. , Ross Julie A. , Olshan Andrew F. , Robison Leslie L. , Smith Franklin O. , Spector Logan G.
Published: September 2007

BACKGROUND.

Children with Down syndrome (DS) have from 10 to 20 times the risk of developing acute leukemia than the general pediatric population. There is mixed evidence for associations between reproductive history or infertility and acute leukemia among children without DS.

METHODS.

The authors conducted a case‐control study of acute leukemia among children with DS to investigate possible risk factors in this population. From 1997 to 2002, 158 children aged <20 years with DS who had a diagnosis of acute leukemia (97 children with acute lymphoblastic leukemia [ALL] and 61 children with acute myeloid leukemia [AML]) were enrolled at Children's Oncology Group (COG) institutions. Controls with DS (n = 173) were selected from the cases' primary care clinic and frequency matched to cases on age. Telephone interviews were conducted with mothers of cases and controls assessing reproductive history, infertility, and infertility treatment.

RESULTS.

Null results were observed overall and by subtype for reproductive factors, including previous pregnancy outcomes and contraceptive use, and for most infertility outcomes. There was an increased risk of AML among children with DS whose parents had ever tried for ≥1 year to become pregnant (odds ratio [OR], 2.22; 95% confidence interval [95% CI], 1.14–4.33). A 1‐year increase in maternal age also was associated with AML (OR, 1.06; 95% CI, 1.01–1.12).

CONCLUSIONS.

Although the questionnaire was limited in this area, the results suggested that the risk for AML may be raised in children with DS because of infertility. In that the risk of infertility, along with having a child with DS, increase with age, these results warrant more research. Cancer 2007. © 2007 American Cancer Society.
Interrogation of Single Synthetic Polymer Chains and Polysaccharides by AFM‐Based Force Spectroscopy
Authors: Giannotti Marina I. , Vancso G. Julius
Published: September 2007

This contribution reviews selected mechanical experiments on individual flexible macromolecules using single‐molecule force spectroscopy (SMFS) based on atomic force microscopy. Focus is placed on the analysis of elasticity and conformational changes in single polymer chains upon variation of the external environment, as well as on conformational changes induced by the mechanical stress applied to individual macromolecular chains. Various experimental strategies regarding single‐molecule manipulation and SMFS testing are discussed, as is theoretical analysis through single‐chain elasticity models derived from statistical mechanics. Moreover, a complete record, reported to date, of the parameters obtained when applying the models to fit experimental results on synthetic polymers and polysaccharides is presented.
Two‐Photon Microscopy and Spectroscopy of Lanthanide Bioprobes
Authors: D'Aléo Anthony , Pompidor Guillaume , Elena Bénédicte , Vicat Jean , Baldeck Patrice L. , Toupet Loïc , Kahn Richard , Andraud Chantal , Maury Olivier
Published: September 2007

The linear and non‐linear photophysical properties of tris‐dipicolinate europium and terbium complexes (absorption, emission, lifetime, luminescence induced by two‐photon absorption) are studied in the crystalline state as well as in protein derivative crystals and compared to those in solution. Upon laser irradiation at 532 nm, luminescence of terbium is induced by a two‐photon antenna effect, whereas luminescence of europium results from one‐photon absorption in forbidden f–f transitions. Finally, linear and two‐photon microscopy imaging experiments on biological and bio‐inspired crystals are performed. These first proof‐of‐concept experiments open the way for the development of time‐resolved non‐linear microscopy that should combine the advantages of lanthanide luminescence (long lifetime, sharp emission bands, insensitivity to oxygen) with those of confocal biphotonic excitation (near‐IR excitation, 3D resolution and reduced photodamage).
Convergence and extension movements affect dynamic notochord‐somite interactions essential for zebrafish slow muscle morphogenesis
Authors: Yin Chunyue , Solnica‐Krezel Lilianna
Published: September 2007

During vertebrate gastrulation, convergence and extension (C&E) movements shape and position the somites that form the fast and slow muscles. In zebrafish knypek;trilobite non‐canonical Wnt mutants, defective C&E movements cause misshapen somites and reduction of slow muscle precursors, the adaxial cells. Here, we demonstrate essential roles of C&E in slow muscle morphogenesis. During segmentation, the adaxial cells change shapes and migrate laterally to form slow muscles at the myotome surface. Using confocal imaging techniques, we show that the adaxial cells undergo three‐step shape changes, including dorsoventral elongation, anterior‐ward rotation, and anteroposterior elongation. The adaxial cells in knypek;trilobite double mutants maintain prolonged contact with the notochord and fail to rotate anteriorly. Such a defect was suppressed by physical removal of their notochord or by introducing wild‐type notochord cells into the mutant. We propose that in the double mutants, impaired C&E movements disrupt notochord development, which impedes the adaxial cell shape changes. Developmental Dynamics 236:2742–2756, 2007. © 2007 Wiley‐Liss, Inc.
Genetic interactions between activin type IIB receptor and Smad2 genes in asymmetrical patterning of the thoracic organs and the development of pancreas islets
Authors: Goto Yutaka , Nomura Masatoshi , Tanaka Kimitaka , Kondo Akiyo , Morinaga Hidetaka , Okabe Taijirou , Yanase Toshihiko , Nawata Hajime , Takayanagi Ryoichi , Li En
Published: September 2007

Signaling through activin type IIB receptor (ActRIIB) has been shown to regulate the axial formation and the development of foregut‐derived organs such as the pancreas in mice. Here, we provide genetic evidence that ActRIIB and Smad2 genes cooperatively regulated asymmetrical patterning of the thoracic organs and pancreas development in mice. The loss of one allele of Smad2 on ActRIIB−/− background resulted in the increased severity of ActRIIB−/− phenotypes, including right pulmonary isomerism and complex cardiac malformations, and resulted in 100% frequency of death soon after birth. Of interest, 14% of compound heterozygous ActRIIB+/−Smad2+/− mice exhibited the ActRIIB−/− phenotypes and died soon after birth. In the pancreas, hypoplastic islets were found not only in ActRIIB−/− but also in Smad2+/− mice. A more severe phenotype was also found in ActRIIB+/−Smad2+/− mice. As well, these mutant mice exhibited impaired glucose tolerance in a gene dosage‐sensitive manner. This genetic evidence strongly suggested that ActRIIB and Smad2 function in the same signaling pathway to regulate axial patterning and pancreas islet formation by means of a threshold mechanism. Developmental Dynamics 236:2865–2874, 2007. © 2007 Wiley‐Liss, Inc.
Imaging the migrating border cell cluster in living Drosophila egg chambers
Authors: Tekotte Hille , Tollervey David , Davis Ilan
Published: September 2007

Cell migration is a key process in animal development and central to the spread of cancer. Border cell migration in Drosophila egg chambers is an excellent general model for cell migration, but lacks techniques for studying this process in living cells. Here, we describe a simple and effective method of preparing egg chambers in halocarbon oil. The movement and behavior of the migrating border cells can reproducibly be followed in up to 25 egg chambers simultaneously by time‐lapse microscopy using a variety of green fluorescent protein markers on a widefield microscope over a period of 4 hr. Our studies reveal a remarkably linear migration route of the border cell cluster and highly dynamic activity within their cluster. Migrating cells rapidly alter their relative positions and generate transient protrusions. These activities are likely to play key roles in the mechanism of migration and cannot readily be analyzed using fixed samples. Developmental Dynamics 236:2818–2824, 2007 © 2007 Wiley‐Liss, Inc.
Serial cloning of pigs by somatic cell nuclear transfer: Restoration of phenotypic normality during serial cloning
Authors: Cho Seong‐Keun , Kim Jae‐Hwan , Park Jong‐Yi , Choi Yun‐Jung , Bang Jae‐Il , Hwang Kyu‐Chan , Cho Eun‐Jeong , Sohn Sea‐Hwan , Uhm Sang Jun , Koo Deog‐Bon , Lee Kyung‐Kwang , Kim Teoan , Kim Jin‐Hoi
Published: September 2007

Somatic cell nuclear transfer (scNT) is a useful way to create cloned animals. However, scNT clones exhibit high levels of phenotypic instability. This instability may be due to epigenetic reprogramming and/or genomic damage in the donor cells. To test this, we produced transgenic pig fibroblasts harboring the truncated human thrombopoietin (hTPO) gene and used them as donor cells in scNT to produce first‐generation (G1) cloned piglets. In this study, 2,818 scNT embryos were transferred to 11 recipients and five G1 piglets were obtained. Among them, a clone had a dimorphic facial appearance with severe hypertelorism and a broad prominent nasal bridge. The other clones looked normal. Second‐generation (G2) scNT piglets were then produced using ear cells from a G1 piglet that had an abnormal nose phenotype. We reasoned that, if the phenotypic abnormality of the G1 clone was not present in the G2 and third‐generation (G3) clones, or was absent in the G2 clones but reappeared in the G3 clones, the phenotypic instability of the G1 clone could be attributed to faulty epigenetic reprogramming rather than to inherent/accidental genomic damage to the donor cells. Blastocyst rates, cell numbers in blastocyst, pregnancy rates, term placenta weight and ponderal index, and birth weight between G1 and G2 clones did not differ, but were significantly (P < 0.05) lower than control age‐ and sex‐matched piglets. Next, we analyzed global methylation changes during development of the preimplantation embryos reconstructed by donor cells used for the production of G1 and G2 clones and could not find any significant differences in the methylation patterns between G1 and G2 clones. Indeed, we failed to detect the phenotypic abnormality in the G2 and G3 clones. Thus, the phenotypic abnormality of the G1 clone is likely to be due to epigenetic dysregulation. Additional observations then suggested that expression of the hTPO gene in the transgenic clones did not appear to be the cause of the phenotypic abnormality in the G1 clones and that the abnormality was acquired by only a few of the G1 clone's cells during its gestational development. Developmental Dynamics 236:3369–3382, 2007. © 2007 Wiley‐Liss, Inc.
Cdc42 is crucial for the establishment of epithelial polarity during early mammalian development
Authors: Wu Xunwei , Li Shaohua , Chrostek‐Grashoff Anna , Czuchra Aleksandra , Meyer Hannelore , Yurchenco Peter D. , Brakebusch Cord
Published: September 2007

To study the role of Cdc42 in the establishment of epithelial polarity during mammalian development, we generated murine Cdc42‐null embryonic stem cells and analyzed peri‐implantation development using embryoid bodies (EBs). Mutant EBs developed endoderm and underlying basement membrane, but exhibited defects of cell polarity, cell–cell junctions, survival, and cavitation. These defects corresponded to a decreased phosphorylation and membrane localization of aPKC, a reduced phosphorylation of GSK3β, and a diminished activity of Rac1. However, neither Rac1 nor the kinase function of GSK3β seem to contribute to cell polarization and cell–cell contacts. In contrast, EBs expressing dominant‐negative (dn) PKCζ mimicked well the phenotype of Cdc42‐null EBs, suggesting a major role of aPKC in mediating cell polarization downstream of Cdc42. Finally, aggregation experiments with endodermal cell lines suggested that Cdc42 might affect formation of adherens and tight junctions by PKCζ‐dependent regulation of the protein levels of p120 catenin and E‐cadherin. Developmental Dynamics 236:2767–2778, 2007. © 2007 Wiley‐Liss, Inc.
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

Notch 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

Thyrotropin‐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

The 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

In 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

Sphingomyelins (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

We 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

Glycosphingolipids 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

The 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

Native 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

The 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

We 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

QCM 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

A 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

PAGE 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

The 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

In 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

Topographic 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

River 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.
Experimental sandstone weathering using different wetting and drying moisture amplitudes
Authors: Sumner P. D. , Loubser M. J.
Published: September 2007

Wetting and drying is an acknowledged yet still poorly understood rock weathering process. Previous experiments documented in the literature measure physical changes or mass loss in relation to moisture oscillations but only one study directly compares different moisture amplitudes by using different modes of moisture application. In this experimental study, four sets of sandstone tablets are subjected to 48 h wetting and drying cycles at set moisture content fluctuations of 29, 42, 56 and 63% respectively. A common moisture application, full immersion, is used for all four sets. Mass loss after 52 cycles averaged 0·27%, some three times more than that of the control samples. Average porosity of the samples increased, while water absorption capacities and the saturation coefficients of the samples decreased. No discernable difference in mass loss or change in physical properties was found between the different sample sets. When compared with previous studies, results suggest that the effect of moisture application type may be more of a controlling factor on the weathering effect than actual moisture content achieved. A need to move towards a more standardized approach in wetting and drying experimental studies is emphasized. Copyright © 2007 John Wiley & Sons, Ltd.
Molecular dynamics study of the interaction of a shock wave with a biological membrane
Authors: Lechuga Javier , Drikakis Dimitris , Pal Sandip
Published: September 2007

This paper presents a computational study of the interaction of a shock wave with a biological membrane. The membrane model comprises 21 555 atoms which build 66 dalmitoyloleoylphosphatidylcholine (POPC) lipids forming the bilayer, and 4237 water molecules, with the distance between the layers being set to fit around the actual membrane thickness (54 Å), and the lattice period being set to fit the actual surface density of lipid molecules. We have employed a molecular dynamics method for solving the Newton equations of motion numerically thereby providing a strategy to understand the basic physics of the biological structure at atomistic level. A shock wave has been modelled as an impulse of 40 Pa s, and simulations for the interaction of the shock wave with the membrane have been performed for 200 ps to investigate the different effects of the shock wave on different membrane properties including thickness, area, volume, order parameter and lateral diffusion. Copyright © 2007 John Wiley & Sons, Ltd.
Numerical solution of the oxygen diffusion problem in cylindrically shaped sections of tissue
Authors: Boureghda Abdellatif
Published: September 2007

A mathematical model is presented which describes the diffusion of oxygen in absorbing tissue, and numerical solution of its partial differential equation is obtained by the finite difference equations. The diffusion with absorption model is associated with the process of a moving boundary which marks the furthest penetration of oxygen in the absorbing cylindrically shaped sections of tissue and also allows for an initial distribution of oxygen through the absorbing tissue. Copyright © 2007 John Wiley & Sons, Ltd.
Finite volume methods and the equations of finite scale: A mimetic approach
Authors: Margolin L. G. , Shashkov M.
Published: September 2007

After introducing the general concept of mimetic differencing, we focus on two specific methodologies, nonoscillatory methods and finite volume approximations. We provide a brief historical account of the development of these two mimetic strategies. We then describe the extension of these strategies to new techniques, a discrete operator calculus and implicit large eddy simulation. In each case, we provide illustrative examples. Further abstraction of these ideas leads to the concept of equations of finite scale, which we advocate as a more appropriate PDE model for constructing numerical algorithms. Published in 2007 by John Wiley & Sons, Ltd.
Efficient computation of steady water flow with waves
Authors: Wackers Jeroen , Koren Barry
Published: September 2007

A surface‐capturing model for steady water flow is presented. This volume‐of‐fluid model without reconstruction consists only of conservation laws, hence, it can be solved very efficiently. The model contains a high‐accuracy compressive water surface discretization and turbulence; it is solved with a linear multigrid technique and defect correction. Results show that the model is accurate and the solver gives fast convergence. Copyright © 2007 John Wiley & Sons, Ltd.
Price discovery in the treasury futures market
Authors: Brandt Michael W. , Kavajecz Kenneth A. , Underwood Shane E.
Published: September 2007

The paper conducts a regression analysis utilizing both futures and cash market prices and net orderflow to determine where price discovery takes place as well as the forces at play that influence the location. Specifically, given the strong theoretical linkage between the U.S. Treasury cash and futures markets, they compare how orderflow contributes to price discovery and analyze how and when information flows from one market to the other. How a number of environmental variables (trader type, financing rates, and liquidity) impact the information flows between these two markets is also considered. Their findings provide new evidence on the extent to which price discovery happens away from a primary market. © 2007 Wiley Periodicals, Inc. Jrl Fut Mark 27: 1021–1051, 2007
Serum and forskolin cooperate to promote G1 progression in Schwann cells by differentially regulating cyclin D1, cyclin E1, and p27Kip expression
Authors: Iacovelli Jared , Lopera Jorge , Bott Marga , Baldwin Elizabeth , Khaled Annette , Uddin Nizam , Fernandez‐Valle Cristina
Published: September 2007

Proliferation of Schwann cells in vitro, unlike most mammalian cells, is not induced by serum alone but additionally requires cAMP elevation and mitogenic stimulation. How these agents cooperate to promote progression through the G1 phase of the cell cycle is unclear. We studied the integrative effects of these compounds on receptor‐mediated signaling pathways and regulators of G1 progression. We show that serum alone induces strong cyclical expression of cyclin D1 and E1, 6 and 12 h after addition, respectively. Serum also promotes strong but transient erbB2, ERK, and Akt phosphorylation, but Schwann cells remain arrested in G1 due to high levels of the inhibitor, p27Kip. Forskolin with serum promotes G1 progression in 22% of Schwann cells between 18 and 24 h by inducing a steady decline in p27Kip levels that reaches a nadir at 12 h coinciding with peak cyclin E1 expression. Forskolin also delays neuregulin‐induced loss of erbB2 receptors allowing strong acute activation of PI3K, sustained erbB2 phosphorylation and G1 progression in 31% of Schwann cells. We find that the ability of forskolin to decrease p27Kip is associated with its ability to decrease Krox‐20 expression that is induced by serum and further increased by neuregulin. Our results explain why serum is required but insufficient to stimulate proliferation and identify two routes by which forskolin promotes proliferation in the presence of serum and neuregulin. These findings provide insights into how G1 progression and, cell cycle arrest leading to myelination are regulated in Schwann cells. © 2007 Wiley‐Liss, Inc.
Lack of P2X receptor mediated currents in astrocytes and GluR type glial cells of the hippocampal CA1 region
Authors: Jabs Ronald , Matthias Katja , Grote Alexander , Grauer Michael , Seifert Gerald , Steinhäuser Christian
Published: September 2007

Purinergic signalling plays a major role in intercellular communication between neurons and glial cells. Glial cells express metabotropic receptors for ATP and adenosine, the latter being activated after ATP cleavage through extracellular ecto‐ATPase activity. Ionotropic receptors for extracellular ATP, so called P2X receptors, might contribute to neuron–glia signalling. However, experimental evidence for the presence of these receptors in glial cells is less convincing so far. In a previous study, immunohistochemistry was used to identify P2X1–4,6,7 receptor protein in S100β‐positive hippocampal glial cells. Applying patch clamp and fast application techniques, here we challenged the question of the functional expression of these receptors. Time correlated membrane currents served as test criterion for receptor function, since P2X receptor activation leads to the opening of unspecific cation channels in a millisecond time scale. Agonists were applied via short pressure puffs, with a fast concentration clamp method and through UV flash triggered photolysis of caged ATP. Two types of murine hippocampal macroglial cells, both labelled by the expression of green fluorescence protein driven by the human glial fibrillary acid protein promoter, were analysed in acute brain slices and in freshly dissociated cell suspensions. Surprisingly, ATP or related agonists completely failed to activate currents. Additionally, changes in spontaneously occurring glial postsynaptic currents were never observed. These results have been verified using rat and human hippocampal tissue as well as investigating cells from P2X7 knock out mice. It is concluded that in acute preparations, astroglial cells of the hippocampal CA1 subfield do not express functional P2X receptors. © 2007 Wiley‐Liss, Inc.
The term structure of credit spreads in project finance
Authors: Sorge Marco , Gadanecz Blaise
Published: September 2007

This paper finds that the term structure of credit spreads in project finance is hump‐shaped. This contrasts with other types of debt, where credit risk is shown instead to increase monotonically with maturity ceteris paribus. We emphasize a number of peculiar features of project finance structures that might underlie this finding, such as high leverage decreasing over time, long‐term political risk guarantees and the sequential resolution of uncertainty along project advancement stages. Our result is particularly relevant given the importance of project finance as a source of long‐term capital for infrastructure especially in developing countries and has implications for risk management in the framework of Basel II. Copyright © 2007 John Wiley & Sons, Ltd.