bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biomechanical properties of intermediate filaments: from tissues to single filaments and back
Authors: Kreplak Laurent , Fudge Douglas 
Published: December 2006

AbstractThe animal cell cytoskeleton consists of three interconnected filament systems: actin‐containing microfilaments (MFs), microtubules (MTs), and the lesser known intermediate filaments (IFs). All IF proteins share a common tripartite domain structure and the ability to assemble into 8–12 nm wide filaments. Electron microscopy data suggest that IFs are built according to a completely different plan from that of MFs and MTs. IFs are known to impart mechanical stability to cells and tissues but, until recently, the biomechanical properties of single IFs were unknown. However, with the discovery of naturally occurring micrometer‐wide IF bundles and the development of new methodologies to mechanically probe single filaments, it is now possible to propose a more unified view of IF biomechanics. Unlike MFs and MTs, single IFs can now be described as flexible, extensible and tough, which has important implications for our understanding of cell and tissue mechanics. Furthermore, the molecular mechanisms at play when IFs are deformed point toward a pivotal role for them in mechanotransduction. BioEssays 29: 26–35, 2007. © 2006 Wiley Periodicals, Inc.
The trick of the tail: protein–protein interactions of metabotropic glutamate receptors
Authors: Enz Ralf 
Published: December 2006

AbstractIt was initially believed that G‐protein‐coupled receptors, such as metabotropic glutamate receptors, could simply be described as individual proteins that are associated with intracellular signal cascades via G‐proteins. This view is no longer tenable. Today we know that metabotropic glutamate receptors (mGluRs) can dimerize and bind to a variety of proteins in addition to trimeric G‐proteins. These newly identified protein interactions led to the discovery of new regulatory mechanisms that are independent of and sometimes synergistic with the classical G‐protein‐coupled second messenger pathways. Notably, several of these mechanisms connect mGluR‐mediated signaling to other receptor classes, thereby creating a network of different receptor types and associated signal cascades. The intracellular C‐termini of mGluRs play a key role in the regulation of these networks, and various new protein interactions of these domains were described recently. Because mGluRs are involved in a variety of physiological and pathophysiological processes, some of the proteins interacting with this receptor class have potential as valuable pharmaceutical targets. This review will give a comprehensive overview of proteins interacting with mGluR C‐termini, highlight new evolving regulatory mechanisms for glutamatergic signal transduction and discuss possibilities for future drug development. BioEssays 29: 60–73, 2007. © 2006 Wiley Periodicals, Inc.
Enhancement of Relaxivity Rates of Gd–DTPA Complexes by Intercalation into Layered Double Hydroxide Nanoparticles
Authors: Xu Zhi Ping , Kurniawan Nyoman D. , Bartlett Perry F. , Lu Gao Qing 
Published: December 2006

AbstractIn this paper we report the preparation and characterization of [Gd(dtpa)]2− intercalated layered double hydroxide (LDH) nanomaterials. [Gd(dtpa)]2− (gadolinium(III) diethylene triamine pentaacetate) was transferred into LDH by anionic exchange. The intercalation of [Gd(dtpa)]2− into LDH was confirmed by X‐ray diffraction for the new phase with the interlayer spacing of 3.5–4.0 nm and by FTIR for the characteristic vibration peaks of [Gd(dtpa)]2−. The morphology of the nanoparticles was influenced by the extent of [Gd(dtpa)]2− loading, in which the poly‐dispersity quality decreased as the [Gd(dtpa)]2− loading was increased. Compared with the morphology of the original Mg2Al–Cl–LDH nanoparticles (hexagonal plate‐like sheets of 50–200 nm), the modified LDH–Gd(dtpa) nanoparticles are bar‐like with a width of 30–60 nm and a length of 50–150 nm. LDH–Gd(dtpa) was expected to have an increased water proton magnetic resonance relaxivity due to the intercalation of [Gd(dtpa)]2− into the LDH interlayer that led to slower molecular anisotropic tumbling compared with free [Gd(dtpa)]2− in solution. Indeed, LDH–nanoparticle suspension containing ≈1.6 mM [Gd(dtpa)]2− exhibits a longitudinal proton relaxivity r1 of ≈16 mM−1 s−1 and a transverse proton relaxivity r2 of ≈50 mM−1 s−1 at room temperature and a magnetic field of 190 MHz, which represents an enhancement four times (r1) and 12 times (r2) that of free [Gd(dtpa)]2− in solution under the same reaction conditions. We have thus tailored LDH–nanoparticles into a novel contrast agent with strong relaxivity, promising for great potential applications in magnetic resonance imaging.
Oligothiophene‐Linked Bisnaphthopyrans: Sequential and Temperature‐Dependent Photochromism
Authors: Zhao Weili , Carreira Erick M. 
Published: December 2006

AbstractPhotochromic bisnaphthopyrans linked with oligothiophenes were synthesized and their photochromic behavior studied. Sequential and temperature‐dependent photochromism was observed in the oligothiophene linked bisnaphthopyrans. The kinetics of photo and thermal processes in bisnaphthopyrans in comparison with naphthopyrans were studied. Substituent and linking effects on the photochromic properties are discussed. We demonstrate that the cross‐talk between the two photochromophores is dependent on the length of the oligothiophene linker. The presence of the bithiophene linker led to high colorability and high quantum yield of coloration.
Pt0 and Pd0 Olefin Complexes of the Metalloid N‐Heterocyclic Carbene Analogues [EI(ddp)] (ddp=2‐{(2,6‐diisopropylphenyl)amino}‐4‐{(2,6‐diisopropylphenyl)imino}‐2‐pentene; E=Al, Ga): Ligand Substitution, HH and SiH Bond Activation, and Cluster Formation
Authors: Kempter Andreas , Gemel Christian , Fischer Roland A. 
Published: December 2006

AbstractVarious products of the reaction of [E(ddp)] (ddp=2‐{(2,6‐diisopropylphenyl)amino}‐4‐{(2,6‐diisopropylphenyl)imino}‐2‐pentene; E=Al, Ga) with Pt0 and Pd0 olefin complexes are reported. Thus, the reaction of [Pt(cod)2] (cod=1,5‐cyclooctadiene) with two equivalents of [Ga(ddp)] yields [Pt(1,3‐cod){Ga(ddp)}2] (1), whereas treatment of [Pd2(dvds)3] (dvds=1,1,3,3‐tetramethyl1,3‐divinyldisiloxane) with [E(ddp)] leads to the monomeric compounds [(dvds)Pd{E(ddp)}] (E=Ga (2 a), Al (2 b)) by substitution of the bridging dvds ligand. Both 1 and 2 a readily react with strong π‐acceptor ligands such as CO or tBuNC to give the dimeric compounds [M{μ2‐Ga(ddp)}(L)] (L=CO, tBuNC; M=Pt (3 a, 5 a), Pd (3 b, 5 b)), respectively. Based on 1H NMR spectroscopic data, [Pt{Ga(ddp)}2(CO)] is likely to be an intermediate in the formation of 3 a. Furthermore, reactions of 1 with H2 and HSiEt3 yield the monomeric compounds [Pt{Ga(ddp)}2(H)2] (7) and [Pt{Ga(ddp)}2(H)(SiEt3)] (8). Finally, the reaction of [Pt(cod)2] with one equivalent of [Ga(ddp)] in the presence of H2 in hexane gives the new dimeric cluster [Pt{μ2‐Ga(ddp)}(H)2]2 (9).
Lightness and hue contrast effects in surface (fabric) colours
Authors: Wu Ray‐Chin , Wardman R. H. 
Published: December 2006

AbstractSimultaneous contrast effects on lightness and hue in surface colours were investigated. Test colours, surrounded by induction colours, were matched by colours surrounded by neutral gray. The matching colours were selected from a series of samples that varied in either lightness or hue respectively. The lightness experiments were carried out by a panel of 20 observers on 135 test/induction colour combinations. The hue experiments were conducted on 51 test/induction colour combinations by a panel of eight observers. The lightness of the test colour was found to decrease linearly with the lightness of the induction colour, regardless of the hue of the induction colour. The magnitude of the lightness contrast effect in fabric colours was found to be about one‐quarter of that found in CRT display colours in a previous study. The hue contrast effect found in this study followed the opponent‐colour theory. Two distinctly different regions could be identified when the hue difference was plotted against hue‐angle difference between the induction colour and the test colour. The slope of the line in the region where the hue of the induction colour is close to the test colour was much larger than the slope in the other region, indicating that the hue contrast effect was more obvious when the induction colour was close to the test colour. © 2006 Wiley Periodicals, Inc. Col Res Appl, 32, 55–64, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20285
Growth and characterization of KBi(WO4)2 single crystals
Authors: Xie H. D. , Shen D. Z. , Wang X. Q. , Shen G. Q. 
Published: December 2006

AbstractPotassium bismuth tungstate [KBi(WO4)2] single crystals with dimensions up to 20 mm × 15 mm × 15 mm have been successfully grown by using the top‐seeded solution growth technique and K2W2O7 as solvent. Experiments show that this crystal is unstable in a strong acid or alkali environment and has a blue fluorescence emission. The density, hardness, melting point, absorption edge, transparency range, prominent Raman shift frequency are 7.57 g/cm3, 238 kg/mm2, 800 °C, 380 nm, 400–5450 nm, 868 cm–1 respectively. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Subcellular compartmentalization of aromatase is sexually dimorphic in the adult zebra finch brain
Authors: Rohmann Kevin N. , Schlinger Barney A. , Saldanha Colin J. 
Published: December 2006

AbstractThe vertebrate brain is a source of estrogen (E) via the expression of aromatase (E‐synthase). In the zebra finch (Taeniopygia guttata), despite documented dimorphisms in E‐action, no differences are detectable in circulating E, or the neural levels of aromatase transcription, activity, or somal protein expression. Studies of aromatase expression at the light‐ and electron‐microscope levels reveal greater numbers of fibers and presynaptic boutons in adult males relative to females. We assayed aromatase activity and content in synaptosomes and microsomes from the anterior [containing lMAN and Area X (males)] and posterior telencephalon (containing HVC and RA) of adult birds. In contrast to non‐song birds and mammals, both cell fractions contain abundant aromatase measurable in terms of activity (enzyme assays) and content (Western blots) with minimal enrichment in microsomes. From brain homogenates of identical concentration, aromatase activity was higher in the synaptosomal relative to the microsomal fraction, in males relative to females, and in the posterior compared to anterior telencephalon. These effects were driven by high levels of synaptosomal aromatase in the male posterior telencephalon. These data suggest that males possess more aromatase per presynaptic bouton, or a greater number of aromatase‐containing presynaptic boutons than females in the posterior telencephalon. Further, the present report reveals synaptic aromatization as a considerable source of E in the zebra finch brain, and supports the idea that telencephalic synapses in and around the adult male song production nuclei may be exposed to higher levels of E compared to the female brain. © 2006 Wiley Periodicals, Inc. J Neurobiol 67: 1–9, 2007
Neuropilin 2/semaphorin 3F signaling is essential for cranial neural crest migration and trigeminal ganglion condensation
Authors: Gammill Laura S. , Gonzalez Constanza , Bronner‐Fraser Marianne 
Published: December 2006

AbstractIn the head of vertebrate embryos, neural crest cells migrate from the neural tube into the presumptive facial region and condense to form cranial ganglia and skeletal elements in the branchial arches. We show that newly formed neural folds and migrating neural crest cells express the neuropilin 2 (npn2) receptor in a manner that is highly conserved in amniotes. The repulsive npn2 ligand semaphorin (sema) 3F is expressed in a complementary pattern in the mouse. Furthermore, mice carrying null mutations for either npn2 or sema3F have abnormal cranial neural crest migration. Most notably, “bridges” of migrating cells are observed crossing between neural crest streams entering branchial arches 1 and 2. In addition, trigeminal ganglia fail to form correctly in the mutants and are improperly condensed and loosely organized. These data show that npn2/sema3F signaling is required for proper cranial neural crest development in the head. © 2006 Wiley Periodicals, Inc. J Neurobiol 67: 47–56, 2007
Participation in management training in a transitioning context: A case of China
Authors: Wang Jia , Wang Greg G. 
Published: December 2006

AbstractThis phenomenological study explores critical issues related to participation in human resource development (HRD) interventions. Specifically focusing on master of business administration (M.B.A.) training programs in China, we conducted in‐depth individual interviews with twelve middle‐level managers to understand their perceptions and experience of this academic program during the country's recent transitional period. The findings suggest that HRD participation in a specific transitioning cultural context may present features that have not been explored by previous learning participation studies in either HRD or adult education. In the light of the transitioning nature of the Chinese cultural context, we derived three propositions for future research on HRD learning participation. Practical implications for learning participation are also drawn based on the results of the study.
Critical role for matrix metalloproteinase‐9 in platelet‐activating factor‐induced experimental tumor metastasis
Authors: Ko Hyun‐Mi , Kang Jee‐Hae , Jung Bongnam , Kim Han‐A , Park Sung Jun , Kim Kyoung‐Jin , Kang Yeong‐Rim , Lee Hern‐Ku , Im Suhn‐Young 
Published: December 2006

AbstractIn this study, the roles of matrix metalloproteinase (MMP)‐2 and MMP‐9 in platelet‐activating factor (PAF)‐induced experimental pulmonary metastasis of the murine melanoma cell, B16F10, were investigated. An injection of PAF resulted in increases in mRNA expression, protein levels and the activities of both MMP‐2 and MMP‐9 in the lungs. The overall expression of MMP‐9 was stronger than that of MMP‐2. The increased MMP‐9 expression was inhibited by both NF‐κB and AP‐1 inhibitors, whereas the increased MMP‐2 expression was inhibited by only AP‐1 inhibitors. Immunohistochemical analysis revealed that MMP‐9 was expressed in bronchial epithelial cells as well as in the walls of blood vessels, whereas MMP‐2 expression was observed only in bronchial epithelial cells. PAF significantly enhanced the pulmonary metastasis of B16F10, which was inhibited by both NF‐κB and c‐jun inhibitors. MMP‐9 inhibitor, but not that of MMP‐2, completely inhibited PAF‐induced B16F10 metastasis. These data indicate that MMP‐9, the expression of which was regulated by NF‐κB and AP‐1, plays a critical role in PAF‐induced enhancement of pulmonary melanoma metastasis. © 2006 Wiley‐Liss, Inc.
The hepatitis B virus X protein promotes hepatocellular carcinoma metastasis by upregulation of matrix metalloproteinases
Authors: Ou Di‐Peng , Tao Yi‐Ming , Tang Fa‐Qing , Yang Lian‐Yue 
Published: December 2006

AbstractThe hepatitis B virus (HBV) is a major cause of human hepatocellular carcinoma (HCC) which has a very high mortality rate due to high incidence of metastasis. It is unknown whether HBV contributes to HCC metastasis. In this report, we present clinical data obtained from HCC patients indicating that the expression of hepatitis B virus X protein (HBx) in HCC is associated with an increased expression of membrane‐type 1 matrix metalloproteinase (MT1‐MMP), and matrix metalloproteinase‐2(MMP‐2), which correlates with a poor prognosis. We further demonstrate experimentally that HBx upregulates MT1‐MMP, which in turn induces MMP‐2. Significantly, HBx‐mediated MMP activation is associated with a marked increase of cell migration, as revealed by both wound‐healing and transwell migration assays, suggesting that HBx may facilitate tumor cell invasion by upregulation of MMPs and subsequent destruction of the extracellular matrix. Together, our results support a model in which HBx contributes to HCC metastasis by upregulation of MMPs. © 2006 Wiley‐Liss, Inc.
Competitive inhibition of carcinogen‐activating CYP1A1 and CYP1B1 enzymes by a standardized complex mixture of PAH extracted from coal tar
Authors: Mahadevan Brinda , Marston Charis P. , Luch Andreas , Dashwood Wan‐Mohaiza , Brooks Eric , Pereira Cliff , Doehmer Johannes , Baird William M. 
Published: December 2006

AbstractA complex mixture of polycyclic aromatic hydrocarbons (PAH) extracted from coal tar, the Standard Reference Material (SRM) 1597, was recently shown to decrease the levels of DNA binding of the 2 strong carcinogens benzo[a]pyrene (BP) and dibenzo[a,l]pyrene (DBP) in the human mammary carcinoma‐derived cell line MCF‐7 (Mahadevan et al., Chem Res Toxicol 2005;18:224–231). The present study was designed to further elucidate the biochemical mechanisms involved in this inhibition process. We examined the effects of SRM 1597 on the metabolic activation of BP and DBP toward DNA‐binding derivatives in Chinese hamster cells expressing either human cytochrome P450 (CYP) 1A1 or CYP1B1. SRM 1597 inhibited BP‐DNA adduct formation through the entire exposure time in cells expressing human CYP1A1, while it significantly inhibited adduct formation only up to 48 hr when co‐treated with DBP. Conversely, human CYP1B1‐expressing cells were unable to catalyze PAH‐DNA adduct formation on treatment with SRM 1597 alone, and on co‐treatment with BP or DBP. The data obtained from biochemical experiments revealed that SRM 1597 competitively inhibited the activity of both human enzymes as analyzed by 7‐ethoxyresorufin O‐deethylation assays. While the Michaelis‐Menten constant (KM) was <0.4 μM in the absence of SRM 1597, this value increased up to 1.12 (CYP1A1) or 4.45 μM (CYP1B1) in the presence of 0.1 μg/ml SRM 1597. Hence the inhibitory effects of the complex mixture on human CYP1B1 were much stronger when compared to human CYP1A1. Taken together, the decreases in PAH‐DNA adduct formation on co‐treatment with SRM 1597 revealed inhibitory effects on the CYP enzymes that convert carcinogenic PAH into DNA‐binding metabolites. The implications for the tumorigenicity of complex environmental PAH mixtures are discussed. © 2006 Wiley‐Liss, Inc.
Effects of methyl paraben on skin keratinocytes
Authors: Ishiwatari S. , Suzuki T. , Hitomi T. , Yoshino T. , Matsukuma S. , Tsuji T. 
Published: December 2006

AbstractSome ingredients of dermatological formulations result in skin irritation and allergy. In particular, preservatives have been reported extensively as a cause of allergic contact dermatitis. The study focused on parabens which have been used extensively as antimicrobial preservatives in foods, drugs and cosmetics. The aim of this study was to clarify the effects of the daily use of methyl paraben (MP) on human skin. The concentrations of MP in the stratum corneum (SC) of the human forearm were measured using the cup method and GC‐MS after daily applications of MP containing formulations. The study also investigated the effects of long‐term exposure to MP on keratinocytes in vitro. Normal human keratinocytes and the skin equivalents were cultured in the medium containing MP. The following changes were analysed: proliferating ability, apoptotic cells, morphological changes, mRNA and protein expressions. After 1 month of daily applications of MP containing formulations, MP remained unmetabolized and persisted slightly in the SC. MP decreased the proliferating ability of keratinocytes and changed the cell morphology. MP also decreased the expressions of hyaluronan synthase 1 and 2 mRNAs and type IV collagen. In contrast, it increased the expressions of involucrin and HSP27. Furthermore, MP influenced the epidermal differentiation of the skin equivalent. These results suggest that MP exposure through application of dermatological formulations results in MP persistence and accumulation in the SC, and that MP might influence the aging and differentiation of keratinocytes. Copyright © 2006 John Wiley & Sons, Ltd.
Nanomechanical analysis of bone tissue engineering scaffolds
Authors: Kaufman Jessica D. , Song Jie , Klapperich Catherine M. 
Published: December 2006

AbstractCopolymers of (2‐hydroxyethyl methacrylate) (HEMA) and methacrylamide monomers conjugated with amino acids were synthesized and crosslinked with ethylene glycol dimethacrylate. The resulting library of copolymers was mineralized in vitro using two distinct methods. In the first mineralization method, the copolymers were polymerized in the presence of a sub‐micron hydroxyapatite (HA) suspension. In the second method, copolymers were mineralized with HA using a urea‐mediated process. The mechanical properties of all of the copolymers, both mineralized and not, were determined using nanoindentation under both load and displacement control. A power law fit to the initial unloading curve was used to determine a reduced elastic modulus for each material. Between 30 and 300 indentations were performed on each material, and ANOVA analysis was run to determine the statistical significance of differences in modulus between samples. Using nanoindentation, the 22 different samples had reduced modulus values ranging from 840 MPa to 4.14 GPa. Aspartic acid‐methacrylate (Asp‐MA) copolymers were not distinguishable from the pHEMA control material. Polymerization in the presence of HA created a more uniform material than the urea method of mineralization. Several challenges and solutions encountered in the nanomechanical testing of soft, heterogeneous materials are discussed. These results demonstrate that with proper experimental design, the mechanical properties of tissue engineering scaffold materials based on polymer‐ceramic composite materials can be determined using small samples and nanoindentation techniques. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res 80A:, 2007
Enhanced antigen‐specific primary CD4+ and CD8+ responses by codelivery of ovalbumin and toll‐like receptor ligand monophosphoryl lipid A in poly(D,L‐lactic‐co‐glycolic acid) nanoparticles
Authors: Hamdy Samar , Elamanchili Praveen , Alshamsan Aws , Molavi Ommoleila , Satou Tadaaki , Samuel John 
Published: December 2006

AbstractThe purpose of this research was to investigate the use of biodegradable poly(D,L‐lactic‐co‐glycolic acid) nanoparticles (PLGA‐NP) as a vaccine delivery system to codeliver antigen, ovalbumin (OVA) along with monophosphoryl lipid A (MPLA) as adjuvant for induction of potent CD4+ and CD8+ T cell responses. The primary CD4+ T responses to OVA/MPLA NP were investigated using OVA‐specific T cells from DO11.10 transgenic mice. Following adoptive transfer of these cells, mice were immunized s.c. by NP formulations. For assessing the CD8+ responses, bone marrow derived dendritic cells (DCs) were pulsed with different OVA formulations, then, cocultured with CD8+ T cells from OT‐1 mice. T cell proliferation/activation and IFN‐γ secretion profile have been examined. Particulate delivery of OVA and MPLA to the DCs lead to markedly increase in in vitro CD8+ T cell T cell proliferative responses (stimulation index >3000) and >13‐folds increase in in vivo clonal expanded CD4+ T cells. The expanded T cells were capable of cytokine secretion and expressed an activation and memory surface phenotype (CD62Llo, CD11ahi, and CD44hi). Codelivery of antigen and MPLA in PLGA‐NP offers an effective method for induction of potent antigen specific CD4+ and CD8+ T cell responses. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res 80A:, 2007