bluuebunny/crossref_metadata_2025 huggingface dataset:
Understanding the properties of interfaces between organic self‐assembled monolayers and noble metals—a theoretical perspective
Authors: Rangger Gerold M. , Romaner Lorenz , Heimel Georg , Zojer Egbert
Published: January 2008

Highly ordered, self‐assembled monolayers (SAMs) on (noble) metal surfaces are of particular importance for both the emerging field of single‐molecule electronics as well as for improving the characteristics of more conventional organic (opto)electronic devices. In the first part of this article, we review the microscopic description of electrode work function modification induced by SAMs and the alignment of molecular states relative to the states in the metal. The focus will be on the Ag(111) surface and biphenyl SAMs involving different donor–acceptor head‐group substituents. The impact of different docking groups will also be discussed and the results will be compared to previous findings (primarily) for SAMs on Au(111). The second part of the article deals with an in‐depth description of charge rearrangements and the hybridization between molecular and metal states by projecting the electronic states of the combined system onto the orbitals of the isolated molecules. Furthermore, the sulfur–silver bond is analyzed by means of a crystal orbital occupation population analysis. Copyright © 2008 John Wiley & Sons, Ltd.
The clinical effects of calcium sulfate combined with calcium carbonate in intrabony defects
Authors: Lee S. B. , Chae G. J. , Jung U. W. , Kim C. S. , Lee Y. K. , Cho K. S. , Chai J. K. , Kim C. K. , Choi S. H.
Published: January 2008

Bone grafts using calcium carbonate (CC) and guided tissue regeneration (GTR) using calcium sulfate (CS) will maximize their advantages and show the best clinical results in intrabony defects. The purpose of this study was to compare the effects of a combination of CS and CC with control treated only with modified widman flap in a periodontal repair of intrabony defects. As many as 30 patients at Yonsei University Hospital were enrolled in this study. Of this group, 10 patients were treated with a combination of CS and CC as the experimental group α another 10 were treated with CC as the experimental group β, and the remaining 10 patients, the control group, were treated only with modified widman flap. The results are follows: (i) The probing depth changes were significantly different (P < 0.05) between the control and experimental group. However, there were no significant differences (P < 0.05) between the experimental group β and α. (ii) The gingival recession changes were not significantly different (P < 0.05) among the groups. (iii) The attachment level changes were significantly different (P < 0.05) between the control and experimental group. However, there were no significant differences (P < 0.05) between the experimental group β and α. (iv) The bone probing depth changes were significantly different (P < 0.05) among the groups. On the basis of these results, it would be concluded that treatment using a combination of CS and CC had the potential to improve periodontal parameters in human intrabony defects. Copyright © 2008 John Wiley & Sons, Ltd.
Experimentell gestützte Verstärkung von Fachwerkknoten
Authors: Gutermann Marc , Meier Bodo , Melzer Veit
Published: January 2008

Füllstäbe von Fachwerkkonstruktionen werden meist über ausgeschnittene Knotenbleche an Ober‐ und Untergurt angeschlossen. Kehlnähte zwischen Flansch und Knotenblech haben sich als wirtschaftliche Verbindung bewährt, da eine Schweißnaht zwischen Steg und Knotenblech sowie aufwendige Einpassarbeiten entfallen. Es wird ein Projekt vorgestellt, bei dem ein Verfahren zur Bemessung von ausgeschnittenen Knotenblechen bei einer Verstärkungsmaßnahme angewendet wurde. Belastungsversuche sichern dabei die Ergebnisse der analytischen Tragwerksplanung ab.
Messung und Auswertung von Verbundträgerverformungen
Authors: Grages Hauke , Lange Jörg
Published: January 2008

Geschossdecken in Stahlverbundbauweise stellen im heutigen Parkhaus‐, Büro‐ und Industriebau eine wirtschaftliche Bauweise für weitgespannte, schlanke Decken dar. Um eine uneingeschränkte Nutzbarkeit des Bauwerks zu gewährleisten, werden im Nachweis der Gebrauchstauglichkeit die zu erwartenden Verformungen, Schwingungen und Rissbreiten ermittelt, die bereits in der Planung durch geeignete Maßnahmen beeinflusst werden können. In der Realität treten jedoch insbesondere bei den Verformungen erhebliche Abweichungen zwischen den berechneten und den am Bauwerk vorhandenen Verformungen auf.

In [1] wurde das Verformungsverhalten von ausgeführten Verbundträgern analysiert, um Vorschläge zu entwickeln, mit denen Verformungen sicherer vorhergesagt werden können. Die Verformungsgeschichte von Verbundträgern wurde an vier Parkhäusern in Stahl‐Beton‐Verbundbauweise während der Bauphase ermittelt. Es zeigte sich, dass sich unter anderem bereits die Fertigung der Stahlträger im Stahlbaubetrieb auf das weitere Verformungsverhalten der Träger auswirkt.
Analyse der Einflüsse auf die Rissbildung infolge Flüssigmetallversprödung beim Feuerverzinken
Authors: Feldmann Markus , Pinger Thomas , Tschickardt Dirk , Bleck Wolfgang , Völling Alexander , Langenberg Peter
Published: January 2008

In dem Beitrag wird, ausgehend von typischen Schadensfällen, der Hintergrund der Rissbildung durch Flüssigmetallversprödung beim Feuerverzinken aufgezeigt. Dabei handelt es sich um ein Phänomen, das in den letzten Jahren verstärkt und nicht selten mit Auswirkung auf die Standsicherheit zu beobachten war. Dies gab Anlass für eingehende Forschungsarbeiten, deren Ergebnisse die Ursachen und Hintergründe der Rissbildung nun wesentlich aufhellen. Sie reichen über das gesamte Spektrum der Problematik, beginnend von den mikroskopischen Befunden, des Korngrenzenangriffs über die Ermittlung von Spannungs‐Dehnungszuständen bis hin zu griffigen Beurteilungsverfahren. Nach der Darstellung der maßgebenden Einflussfaktoren wie Zinkschmelzenzusammensetzung, Spannungs‐ Dehnungsentwicklung, Material, etc. werden auf Grundlage der aktuellen Forschungsergebnisse Empfehlungen zur Vermeidung der Rissbildung abgeleitet und vorgestellt.
Analysis of long chain sultones by thin layer chromatography
Authors: Wolf T. , McPherson B. P.
Published: January 2008

Abstract and Summary

The separation and semiquantitative estimation of nine C14 sultones by thin layer chromatography (TLC) on silica gel is reported. Vapor phase charring gives detection limits of several ppm in olefin sulfonate, ethoxylated alcohol sulfates, and formulated products. Isopropyl ether is the solvent of choice, and two‐dimensional TLC with this and a chlorinated solvent mixture gives an exclusive sultone area, as well as added sensitivity. Simplified preparative TLC on plates with preadsorbent is described for confirmation by independent analytical methods.
Synergistic antioxidant effect of nucleic acids and tocopherols
Authors: Ikeda Nobuo , Fukuzumi Kazuo
Published: January 2008

Abstract and Summary

Nucleic acids acted as synergists with tocopherols in inhibiting the oxidation of methyl linoleate. DNA and RNA enhanced the activity of tocopherols to different extents in the order α‐>γ‐>δ‐tocopherol. Nucleic acids decreased the rates of consumption of tocopherol in the presence of oxi‐dizing methyl linoleate. Nucleic acids also decreased the rate of oxidation of tocopherols by PbO2. The synergistic effect of nucleic acids seemed to be caused by hydrogen bond formation with tocopherols which protected toco‐pherols from direct air oxidation.
Computer‐ Controlled Automatic titration system and its application to the analysis of fats and oils
Authors: Fudano Shintaro , Kusuyama Takashi , Yashima Kazuaki , Terai Sakiko , Konishi Kazuo
Published: January 2008

Abstract and Summary

An automatic titration system (ATS) controlled by a microcomputer was developed for potentiometric or pH titrations. The titrator is equipped with a piston‐type glass buret which is operated by a stepping motor driven by computer‐generated pulse. The droplet volume of titrant is 0.00211 ml per pulse which enables very accurate titration. The titration rate is controlled by regulating the intervals of pulses according to the potential changes accompanying the progress of titration. The point giving the maximum pulse interval is detected automatically as the end point. Accordingly, it is not necessary to present the potential or pH value of the end point. Sample beakers are sent in turn with an endless mode. As examples of practical application of ATS, saponification value, amine value, acid value, total chlorine content, and chloride ion content were determined. The ATS makes it possible to contribute not only to the improvement of precision but to the simplification of analytical procedures in fats and oils chemistry.
Apoptotic Effects of Dietary and Synthetic Sphingolipids in Androgen‐Independent (PC‐3) Prostate Cancer Cells
Authors: Kent Kyle D. , Clubbs Elizabeth A. , Harper W. James , Bomser Joshua A.
Published: January 2008

Stress‐induced activation and metabolism of plasma membrane sphingolipids results in intracellular ceramide accumulation and has been shown to induce apoptosis in human prostate cancer cells. This effect has been observed using synthetic ceramide analogs, such as C6‐ceramide; however, the effects of naturally‐occurring sphingolipids, such as C18‐ceramide and sphingomyelin (CerPCho), on apoptosis and prostate cancer cell proliferation have not been examined. The results of the present study demonstrate that natural (CerPCho, C18‐ceramide) and synthetic (C6‐ceramide) sphingolipids reduced PC‐3 cell proliferation by 15 ± 1.8, 17 ± 2.5, and 46 ± 2.1%, respectively (P < 0.05). These reductions in proliferation were due, in part, to increased cellular apoptosis. Treatment of PC‐3 cells with CerPCho and C18‐ceramide significantly increased apoptosis by 3.0 ± 0.8 and 3.6 ± 0.6%, respectively, compared to the untreated control, while the synthetic C6‐ceramide significantly increased apoptosis by 55.7 ± 0.4%. C6‐ceramide‐induced apoptosis was associated with cell cycle arrest in the G2/M phase, decreased extracellular signal‐regulated kinase (ERK1/2) signaling and activation of the cell cycle regulatory protein, retinoblastoma (pRb). Treatment of PC‐3 cells with C18‐ceramide and CerPCho did not alter cell cycle distribution, pRb or ERK1/2 activation. Taken together, these results suggest that natural and synthetic sphingolipids induce apoptosis in PC‐3 cells via distinct signaling mechanisms and potencies.
Characterization and Oxidative Stability of Structured Lipids: Infant Milk Fat Analog
Authors: Maduko C. O. , Park Y. W. , Akoh C. C.
Published: January 2008

Structured lipids (SLs) for infant milk formulation were produced by enzymatic interesterification of tripalmitin with vegetable oil blends and fish oil. The SLs were characterized by fatty acid content and structure, melting profiles, oxidative stability index, free fatty acid (FFA) concentration, and tocopherol content. Oxidative stability was studied using accelerated methods by quantifying FFA, peroxides (peroxide value) and aldehydes (p‐anisidine value) production. Total oxidation (TOTOX value) was calculated as 2 × (peroxide value) + (p‐anisidine value). The structured lipids after purification by distillation and addition of antioxidants had melting profiles, oxidative stability index, and initial FFA concentration that were similar to that of the starting oil blends, while the fatty acid composition and structure of the SLs were similar to that of human milk fat. Oxidative stability of the SLs was improved with tocopherol addition as antioxidants and was comparable to that of the vegetable oils and oil blends.
Transcriptional enhancer factor 1 (TEF‐1/TEAD1) mediates activation of IFITM3 gene by BRGl
Authors: Cuddapah Suresh , Cui Kairong , Zhao Keji
Published: January 2008

The interferon inducible transmembrane (IFITM) proteins mediate several cellular processes such as homotypic cell adhesion functions of interferons (IFNs) and cellular anti‐proliferative activities. We show that the BAF complex‐mediated induction of IFITM3 is dependent on binding of the transcriptional enhancer factor 1 (TEF‐1/TEAD1) to the M‐CAT like elements of its promoter. TEF‐1 knock‐down reduced the BAF complex‐mediated activation of IFITM3 promoter. In the absence of the BAF complex, TEF‐1 is repressive to IFITM3 expression. The regulation of IFITM3 by TEF‐1 demonstrates that TEF‐1 dependent regulation is more widespread than its previously established role in the expression of muscle specific genes.
WEYL'S THEOREM FOR CLASSA(k) OPERATORS
Authors: IRENE MARY J. STELLA , PANAYAPPAN S.
Published: January 2008

In this paper we shall show that Weyl's theorem holds for classA(k) operatorsTwherek≥>1, via its hyponormal transform$\skew3\hat{T}$. Next we shall prove some applications of Weyl's theorem on classA(k) operators.
ON A FRIEDRICHS EXTENSION RELATED TO UNBOUNDED SUBNORMALS-II
Authors: CHAVAN SAMEER
Published: January 2008

We study the Friedrichs extensions of unbounded cyclic subnormals. The main result of the present paper is the identification of the Friedrichs extensions of certain cyclic subnormals with their closures. This generalizes as well as complements the main result obtained in [5]. Such characterizations lead to abstract Galerkin approximations, generalized wave equations, and bounded${\mathcal H}^{\infty}$-functional calculi.
ASYMPTOTIC BEHAVIOR OF EIGENVALUES OF RECIPROCAL POWER LCM MATRICES
Authors: HONG SHAOFANG , ENOCH LEE K. S.
Published: January 2008

Let$\{x_i\}_{i=1}^{\infty}$be an arbitrary strictly increasing infinite sequence of positive integers. For an integern≥1, let$S_n=\{x_1, {\ldots}\, x_n\}$. Letr>0 be a real number andq≥ 1 a given integer. Let$\lambda _n^{(1)}\, {\le}\, {\ldots}\, {\le}\, \lambda _n^{(n)}$be the eigenvalues of the reciprocal power LCM matrix$(\frac{1}{[x_i, x_j]^r})$having the reciprocal power${1\over {[x_i, x_j]^r}}$of the least common multiple ofxiandxjas itsi,j-entry. We show that the sequence$\{\lambda _n^{(q)}\}_{n=q}^{\infty}$converges and${\rm lim}_{n\, {\rightarrow}\, \infty}\lambda _n^{(q)}=0$. We show that the sequence$\{\lambda _n^{(n-q+1)}\}_{n=q}^{\infty}$converges if$s_r:=\sum_{i=1}^{\infty}{1\over {x_i^r}}<\infty $and${\rm lim}_{n\, {\rightarrow}\, \infty}\lambda _n^{(n-q+1)}\, {\le}\, s_r$. We show also that ifr> 1, then the sequence$\{\lambda _{ln}^{(tn-q+1)}\}_{n=1}^{\infty}$converges and${\rm lim}_{n\, {\rightarrow}\, \infty}\lambda _{ln}^{(tn-q+1)}=0$, wheretandlare given positive integers such thatt≤l−1.
MOUFANG QUADRANGLES OF MIXED TYPE
Authors: STRUYVE KOEN , VAN MALDEGHEM HENDRIK
Published: January 2008

In this paper, we present some geometric characterizations of the Moufang quadrangles of mixed type, i.e., the Moufang quadrangles all the points and lines of which are regular. Roughly, we classify generalized quadrangles with enough (to be made precise) regular points and lines with the property that the dual nets associated to the regular points satisfy the Axiom of Veblen-Young, or a very weak version of the Axiom of Desargues. As an application we obtain a geometric characterization and axiomatization of the generalized inversive planes arising from the Suzuki-Tits ovoids related to a polarity in a mixed quadrangle. In the perfect case this gives rise to a characterization with one axiom less than in a previous result by the second author.
Zervikale Lymphknotenschwellung
Authors: Erb S. , Nüesch R.
Published: January 2008

Eine 49-jährige, seit vielen Jahren in der Schweiz lebende Philippina stellte sich wegen einer chronischen zervikalen einseitigen Lymphknotenschwellung vor. Nach serologischem Ausschluss diverser mikrobiologischer Ursachen wurde eine Feinnadelpunktion durchgeführt, welche jedoch nicht konklusiv war. Die Anamnese und ein stark positiver Mantouxtest lenkten den Verdacht auf eine Lymphknotentuberkulose. Diese konnte schlussendlich dank einer Lymphknotenexzisionsbiopsie mit histologischer und kultureller Aufarbeitung bestätigt werden, worauf eine tuberkulostatische Therapie über 6 Monate eingeleitet wurde.
Hedging rule for reservoir operations: 2. A numerical model
Authors: You Jiing‐Yun , Cai Ximing
Published: January 2008

Optimization models for reservoir operation analysis usually use a heuristic algorithm to search for the hedging rule. This paper presents a method that derives a hedging rule from theoretical analysis (J.‐Y. You and X. Cai, 2008) with an explicit two‐period Markov hydrology model, a particular form of nonlinear utility function, and a given inflow probability distribution. The unique procedure is to embed hedging rule derivation based on the marginal utility principle into reservoir operation simulation. The simulation method embedded with the optimization principle for hedging rule derivation will avoid both the inaccuracy problem caused by trail and error with traditional simulation models and the computational difficulty (“curse of dimensionality”) with optimization models. Results show utility improvement with the hedging policy compared to the standard operation policy (SOP), considering factors such as reservoir capacity, inflow level and uncertainty, price elasticity and discount rate. Following the theoretical analysis presented in the companion paper, the condition for hedging application, the starting water availability and ending water availability for hedging, is reexamined with the numerical example; the probabilistic performance of hedging and SOP regarding water supply reliability is compared; and some findings from the theoretical analysis are verified numerically.
Water masses labeled with global fallout 137Cs formed by subduction in the North Pacific
Authors: Aoyama Michio , Hirose Katsumi , Nemoto Kazuhiro , Takatsuki Yasushi , Tsumune Daisuke
Published: January 2008

We provide a first cross section of the 137Cs concentration along 165°E longitude in the western North Pacific. The 137Cs profile is characterized by several subsurface cores with high 137Cs, including two 137Cs concentration maxima at 20°N, one at 250 m (σθ ≈ 25.5) and one at 400–500 m (σθ ≈ 26.0) depths. The shallower maximum is in the density range of North Pacific Subtropical Mode Water (NPSTMW) and the deeper one is in the density range of Lighter Central Mode Water (LCMW). The main 137Cs cores, therefore, were formed by movements of NPSTMW and LCMW in the interior ocean during the past four decades. The 137Cs has been transported from subarctic region to subtropics and tropics as a result of subduction.
Contribution of soil moisture retrievals to land data assimilation products
Authors: Reichle R. H. , Crow W. T. , Koster R. D. , Sharif H. O. , Mahanama S. P. P.
Published: January 2008

Satellite measurements (retrievals) of surface soil moisture are subject to errors and cannot provide complete space‐time coverage. Data assimilation systems merge available retrievals with information from land surface models and antecedent meteorological data, information that is spatio‐temporally complete but likewise uncertain. For the design of new satellite missions it is critical to understand just how uncertain retrievals can be and still be useful. Here, we present a synthetic data assimilation experiment that determines the contribution of retrievals to the skill of land assimilation products (soil moisture and evapotranspiration) as a function of retrieval and land model skill. As expected, the skill of the assimilation products increases with the skill of the model and that of the retrievals. The skill of the soil moisture assimilation products always exceeds that of the model acting alone; even retrievals of low quality contribute information to the assimilation product, particularly if model skill is modest.
Photoelectron impact excitation of OI 8446 Å emission observed from Arecibo Observatory
Authors: Waldrop L. S. , Kerr R. , Richards P.
Published: January 2008

Photoelectron (PE) impact on thermospheric oxygen atoms is a major source of OI 8446 Å emission excitation at midlatitudes. However, historical discrepancies between observed twilight emission brightnesses and PE model predictions have not only prompted speculation regarding secondary sources of excitation but also precluded the use of observed brightness as a much‐needed diagnostic of thermospheric O density. In an effort to improve understanding of the physical mechanisms responsible for its excitation, this paper presents new photometric measurements of twilight OI 8446 Å emission brightness, together with calculations using the Field Line Interhemispheric Plasma (FLIP) PE model, acquired from Arecibo Observatory under geomagnetically quiet conditions during three winter campaigns from 1999–2002. Winter is a particularly favorable season for twilight 8446 Å observation in the northern hemisphere since significant PE production, and thus 8446 Å excitation, persists for several hours in the fully illuminated, geomagnetic conjugate hemisphere in the absence of any local thermospheric illumination. The winter 8446 Å brightness data are fully consistent with a dominant PE impact excitation source. However, the new data also confirm the Lancaster et al. (2000) report of excess early morning brightness at Arecibo with respect to PE models which use a tilted‐dipole approximation to the geomagnetic field. By using the International Geomagnetic Reference Field (IGRF) geomagnetic field model to refine Arecibo's conjugate point location specified in the FLIP PE model, we demonstrate significantly improved agreement between the modeled and observed brightness decay profiles during both morning and evening twilight intervals.
Estimating profile soil moisture and groundwater variations using GRACE and Oklahoma Mesonet soil moisture data
Authors: Swenson Sean , Famiglietti James , Basara Jeffrey , Wahr John
Published: January 2008

In this study we estimate a time series of regional groundwater anomalies by combining terrestrial water storage estimates from the Gravity Recovery and Climate Experiment (GRACE) satellite mission with in situ soil moisture observations from the Oklahoma Mesonet. Using supplementary data from the Department of Energy's Atmospheric Radiation Measurement (DOE ARM) network, we develop an empirical scaling factor with which to relate the soil moisture variability in the top 75 cm sampled by the Mesonet sites to the total variability in the upper 4 m of the unsaturated zone. By subtracting this estimate of the full unsaturated zone soil moisture anomalies, we arrive at a time series of groundwater anomalies, spatially averaged over a region approximately 280,000 km2 in area. Results are compared to observed well level data from a larger surrounding region, and show consistent phase and relative inter‐annual variability.
Mannose Binding Lectin Gene Deficiency Increases Susceptibility to Traumatic Brain Injury in Mice
Authors: Yager Phoebe H , You Zerong , Qin Tao , Kim Hyung-Hwan , Takahashi Kazue , Ezekowitz Alan B , Stahl Gregory L , Carroll Michael C , Whalen Michael J
Published: January 2008

Mannose binding lectin (MBL) initiates complement activation and exacerbates tissue damage after systemic ischemia/reperfusion. We tested the hypothesis that MBL activates complement and worsens outcome using two levels of controlled cortical impact (CCI) in mice. After moderate CCI (0.6 mm depth), MBL immunostaining was detected on injured endothelial cells of wild-type (WT) mice and C3d was detected in MBL KO (deficient in MBL A/C) and WT mice, suggesting that MBL is dispensable for terminal complement activation after CCI. Brain neutrophils, edema, blood-brain barrier permeability, gross histopathology, and motor dysfunction were similar in injured MBL KO and WT mice. In mice subjected to mild CCI (0.2 mm), MBL KO mice had almost two-fold increased acute CA3 cell degeneration at 6 h ( P<0.01 versus WT). Naive MBL KO mice had decreased brain volume but performed similar to WT mice in two distinct Morris water maze (MWM) paradigms. However, injured MBL KO mice had impaired performance in cued platform trials (P<0.05 versus WT), suggesting a transient nonspatial learning deficit in injured MBL KO mice. The data suggest that MBL deficiency increases susceptibility to CCI through C3-independent mechanisms and that MBL-deficient patients may be at increased risk of poor outcome after traumatic brain injury.
Intracellular localization of human Ins(1,3,4,5,6)P5 2-kinase
Authors: Brehm Maria A. , Schenk Tobias M. H. , Zhou Xuefei , Fanick Werner , Lin Hongying , Windhorst Sabine , Nalaskowski Marcus M. , Kobras Mario , Shears Stephen B. , Mayr Georg W.
Published: January 2008

InsP6 is an intracellular signal with several proposed functions that is synthesized by IP5K [Ins(1,3,4,5,6)P5 2-kinase]. In the present study, we overexpressed EGFP (enhanced green fluorescent protein)–IP5K fusion proteins in NRK (normal rat kidney), COS7 and H1299 cells. The results indicate that there is spatial microheterogeneity in the intracellular localization of IP5K that could also be confirmed for the endogenous enzyme. This may facilitate changes in InsP6 levels at its sites of action. For example, overexpressed IP5K showed a structured organization within the nucleus. The kinase was preferentially localized in euchromatin and nucleoli, and co-localized with mRNA. In the cytoplasm, the overexpressed IP5K showed locally high concentrations in discrete foci. The latter were attributed to stress granules by using mRNA, PABP [poly(A)-binding protein] and TIAR (TIA-1-related protein) as markers. The incidence of stress granules, in which IP5K remained highly concentrated, was further increased by puromycin treatment. Using FRAP (fluorescence recovery after photobleaching) we established that IP5K was actively transported into the nucleus. By site-directed mutagenesis we identified a nuclear import signal and a peptide segment mediating the nuclear export of IP5K.
Characterization of an exported monoglyceride lipase from Mycobacterium tuberculosis possibly involved in the metabolism of host cell membrane lipids
Authors: Côtes Karen , Dhouib Rabeb , Douchet Isabelle , Chahinian Henri , de Caro Alain , Carrière Frédéric , Canaan Stéphane
Published: January 2008

The Rv0183 gene of the Mycobacterium tuberculosis H37Rv strain, which has been implicated as a lysophospholipase, was cloned and expressed in Escherichia coli. The purified Rv0183 protein did not show any activity when lysophospholipid substrates were used, but preferentially hydrolysed monoacylglycerol substrates with a specific activity of 290 units·mg−1 at 37 °C. Rv0183 hydrolyses both long chain di- and triacylglycerols, as determined using the monomolecular film technique, although the turnover was lower than with MAG (monoacyl-glycerol). The enzyme shows an optimum activity at pH values ranging from 7.5 to 9.0 using mono-olein as substrate and is inactivated by serine esterase inhibitors such as E600, PMSF and tetrahydrolipstatin. The catalytic triad is composed of Ser110, Asp226 and His256 residues, as confirmed by the results of site-directed mutagenesis. Rv0183 shows 35% sequence identity with the human and mouse monoglyceride lipases and well below 15% with the other bacterial lipases characterized so far. Homologues of Rv0183 can be identified in other mycobacterial genomes such as Mycobacterium bovis, Mycobacterium smegmatis, and even Mycobacterium leprae, which is known to contain a low number of genes involved in the replication process within the host cells. The results of immunolocalization studies performed with polyclonal antibodies raised against the purified recombinant Rv0183 suggested that the enzyme was present only in the cell wall and culture medium of M. tuberculosis. Our results identify Rv0183 as the first exported lipolytic enzyme to be characterized in M. tuberculosis and suggest that Rv0183 may be involved in the degradation of the host cell lipids.
The selectivity of protein kinase inhibitors: a further update
Authors: Bain Jenny , Plater Lorna , Elliott Matt , Shpiro Natalia , Hastie C. James , Mclauchlan Hilary , Klevernic Iva , Arthur J. Simon C. , Alessi Dario R. , Cohen Philip
Published: January 2008

The specificities of 65 compounds reported to be relatively specific inhibitors of protein kinases have been profiled against a panel of 70–80 protein kinases. On the basis of this information, the effects of compounds that we have studied in cells and other data in the literature, we recommend the use of the following small-molecule inhibitors: SB 203580/SB202190 and BIRB 0796 to be used in parallel to assess the physiological roles of p38 MAPK (mitogen-activated protein kinase) isoforms, PI-103 and wortmannin to be used in parallel to inhibit phosphatidylinositol (phosphoinositide) 3-kinases, PP1 or PP2 to be used in parallel with Src-I1 (Src inhibitor-1) to inhibit Src family members; PD 184352 or PD 0325901 to inhibit MKK1 (MAPK kinase-1) or MKK1 plus MKK5, Akt-I-1/2 to inhibit the activation of PKB (protein kinase B/Akt), rapamycin to inhibit TORC1 [mTOR (mammalian target of rapamycin)–raptor (regulatory associated protein of mTOR) complex], CT 99021 to inhibit GSK3 (glycogen synthase kinase 3), BI-D1870 and SL0101 or FMK (fluoromethylketone) to be used in parallel to inhibit RSK (ribosomal S6 kinase), D4476 to inhibit CK1 (casein kinase 1), VX680 to inhibit Aurora kinases, and roscovitine as a pan-CDK (cyclin-dependent kinase) inhibitor. We have also identified harmine as a potent and specific inhibitor of DYRK1A (dual-specificity tyrosine-phosphorylated and -regulated kinase 1A) in vitro. The results have further emphasized the need for considerable caution in using small-molecule inhibitors of protein kinases to assess the physiological roles of these enzymes. Despite being used widely, many of the compounds that we analysed were too non-specific for useful conclusions to be made, other than to exclude the involvement of particular protein kinases in cellular processes.
The widely utilized brominated flame retardant tetrabromobisphenol A (TBBPA) is a potent inhibitor of the SERCA Ca2+ pump
Authors: Ogunbayo Oluseye A. , Michelangeli Francesco
Published: January 2008

TBBPA (tetrabromobisphenol A) is currently the most widely used type of BFR (brominated flame retardant) employed to reduce the combustibility of a large variety of electronic and other manufactured products. Recent studies have indicated that BFRs, including TBBPA, are bio-accumulating within animal and humans. BFRs including TBBPA have also been shown to be cytotoxic and potentially endocrine-disrupting to a variety of cells in culture. Furthermore, TBBPA has specifically been shown to cause disruption of Ca2+ homoeostasis within cells, which may be the underlying cause of its cytotoxicity. In this study, we have demonstrated that TBBPA is a potent non-isoform-specific inhibitor of the SERCA (sarcoplasmic/endoplasmic reticulum Ca2+-ATPase) (apparent Ki 0.46–2.3 μM), thus we propose that TBBPA inhibition of SERCA contributes in some degree to Ca2+ signalling disruption. TBBPA binds directly to the SERCA without the need to partition into the phospholipid bilayer. From activity results and Ca2+-induced conformational results, it appears that the major effect of TBBPA is to decrease the SERCA affinity for Ca2+ (increasing the Kd from approx. 1 μM to 30 μM in the presence of 10 μM TBBPA). Low concentrations of TBBPA can quench the tryptophan fluorescence of the SERCA and this quenching can be reversed by BHQ [2,5-di-(t-butyl)-1,4-hydroquinone] and 4-n-nonylphenol, but not thapsigargin, indicating that TBBPA and BHQ may be binding to similar regions in the SERCA.
Tuning the formation of a covalent haem–protein link by selection of reductive or oxidative conditions as exemplified by ascorbate peroxidase
Authors: Metcalfe Clive L. , Daltrop Oliver , Ferguson Stuart J. , Raven Emma Lloyd
Published: January 2008

Previous work [Metcalfe, Ott, Patel, Singh, Mistry, Goff and Raven (2004) J. Am. Chem. Soc. 126, 16242–16248] has shown that the introduction of a methionine residue (S160M variant) close to the 2-vinyl group of the haem in ascorbate peroxidase leads to the formation of a covalent haem–methionine linkage under oxidative conditions (i.e. on reaction with H2O2). In the present study, spectroscopic, HPLC and mass spectrometric evidence is presented to show that covalent attachment of the haem to an engineered cysteine residue can also occur in the S160C variant, but, in this case, under reducing conditions analogous to those used in the formation of covalent links in cytochrome c. The data add an extra dimension to our understanding of haem to protein covalent bond formation because they show that different types of covalent attachment (one requiring an oxidative mechanism, the other a reductive pathway) are both accessible within same protein architecture.
A role for SUMO modification in transcriptional repression and activation
Authors: Lyst M.J. , Stancheva I.
Published: January 2008

Since the discovery of the SUMO (small ubiquitin-related modifier) family of proteins just over a decade ago, a plethora of substrates have been uncovered including many regulators of transcription. Conjugation of SUMO to target proteins has generally been considered as a repressive modification. However, there are now a growing number of examples where SUMOylation has been shown to activate transcription. Here, we discuss whether there is something intrinsically repressive about SUMOylation, or if the outcome of this modification in the context of transcription will prove to be largely substrate-dependent. We highlight some of the technical challenges that will be faced by attempting to answer this question.
Daxx mediates SUMO-dependent transcriptional control and subnuclear compartmentalization
Authors: Shih H.-M. , Chang C.-C. , Kuo H.-Y. , Lin D.-Y.
Published: January 2008

SUMO (small ubiquitin-related modifier) modification is emerging as an important post-translational control in transcription. In general, SUMO modification is associated with transcriptional repression. Although many SUMO-modified transcription factors and co-activators have been identified, little is known about the mechanism underlying SUMOylation-elicited transcriptional repression. Here, we summarize that SUMO modification of transcription factors such as androgen receptor, glucocorticoid receptor, Smad4 and CBP [CREB (cAMP-response-element-binding protein)-binding protein] co-activator results in the recruitment of a transcriptional co-repressor Daxx, thereby causing transcriptional repression. Such a SUMO-dependent recruitment of Daxx is mediated by the interaction between the SUMO moiety of SUMOylated factors and Daxx SUMO-interacting motif. Interestingly, the transrepression effect of Daxx on these SUMOylated transcription factors can be relieved by SUMOylated PML (promyelocytic leukaemia) via altering Daxx partition from the targeted gene promoter to PML nuclear bodies. Because Daxx SUMO-interacting motif is a common binding site for SUMOylated factors, a model of competition for Daxx recruitment between SUMOylated PML and SUMOylated transcription factors was proposed. Together, our findings strongly suggest that Daxx functions as a SUMO reader in the SUMO-dependent regulation of transcription and subnuclear compartmentalization.
Viral control of the SUMO pathway: Gam1, a model system
Authors: Chiocca S.
Published: January 2008

SUMO (small ubiquitin-related modifier) is a ubiquitin-like family member that is conjugated to its substrates through discrete enzymatic steps: activation, involving the E1 enzyme [SAE (SUMO-activating enzyme) 1–SAE2], conjugation, involving the E2 enzyme [Ubc9 (ubiquitin-conjugating enzyme 9)], and substrate modification, through the co-operation of Ubc9 and E3 protein ligases. Work from our laboratory has shown the first example of a viral protein, Gam1, that binds to the E1 heterodimer, inhibiting its function and causing a complete block of the SUMOylation pathway both in vivo and in vitro, followed by SAE1–SAE2 degradation. The mechanism by which a viral protein inactivates and subsequently degrades an essential cellular enzyme, arresting a key regulatory pathway, will be discussed. Although four distinct SUMO isoforms have been described, I will use SUMO to describe the entire system.
Modulation of transcriptional activity of the DEAD-box family of RNA helicases, p68 (Ddx5) and DP103 (Ddx20), by SUMO modification
Authors: Fuller-Pace F.V. , Jacobs A.-M.F. , Nicol S.M.
Published: January 2008

SUMO (small ubiquitin-related modifier) modification is known to have diverse effects on the activity of transcriptional regulators, often through alterations in their localization or interactions with other factors, and in most of the cases is associated with transcriptional repression. The DEAD-box family of RNA helicases includes a large number of proteins that are involved in various cellular processes. Several members are now known to be multifunctional and their activities are thought to be governed by interactions with other partners, which may be regulated by post-translational modifications. In the present paper, we shall briefly review recent evidence indicating that SUMO modification is important in modulating the activity of two DEAD-box proteins, p68 (Ddx5) and DP103 (Ddx20), which are known to be important transcriptional regulators.
Ubc9 fusion-directed SUMOylation (UFDS)
Authors: Niedenthal R.
Published: January 2008

SUMOylation is a post-translational modification that is involved in the regulation of proteins of different cellular processes. Dependent on the transient, small SUMOylated portion of most target proteins, it is difficult to identify and characterize this modification and its functions, and it is even more difficult to study the interplay between SUMOylation and other modifications on a specific protein. To facilitate the analysis of protein SUMOylation and its interplay with other protein modifications, the UFDS (Ubc9 fusion-directed SUMOylation) system has been developed. The identification of new SUMOylation substrates and the elucidation of the interplay between STAT1 (signal transducer and activator of transcription 1) phosphorylation and SUMOylation demonstrate UFDS as a useful tool for analysing protein SUMOylation.
Papillomaviruses and the host SUMOylation system
Authors: Wu Y.-C. , Deyrieux A.F. , Wilson V.G.
Published: January 2008

SUMOylation of viral proteins is widespread and serves to modify or regulate the properties of those proteins. Papillomaviruses are a large group of small DNA viruses that infect the skin, leading to benign lesions (warts) that in some cases can progress to malignancy. The papillomavirus life cycle is intimately connected with the differentiation process of stratified epithelium, and several viral early proteins function to modulate the host cell environment. One of the critical early proteins is the E2 protein, which functions in both viral replication and transcription. In the present paper, we demonstrate that E2 proteins are SUMOylated and that overexpression of SUMOylation results in a dramatic increase in intracellular levels of the E2 protein. We have shown previously that there is increased SUMOylation during keratinocyte differentiation, suggesting that the levels of E2 protein may be tied to changes in the cellular SUMOylation state during differentiation. In addition to itself being regulated by SUMOylation, E2 appears to influence the SUMOylation state of one of its binding partners, the cellular transcription factor, C/EBP (CCAAT/enhancer-binding protein). Overall, these observations indicate a complex interplay between this viral protein and the host SUMOylation system.
Building an immune system from nine domains
Authors: Pålsson-McDermott E.M. , O'Neill L.A.J.
Published: January 2008

Four families of PRRs (pattern-recognition receptors) have been identified as important components of innate immunity, participating in the sensory system for host defence against the invasion of infectious agents. The TLRs (Toll-like receptors) recognize a variety of conserved microbial PAMPs (pathogen-associated molecular patterns) derived from bacteria, viruses, protozoa and fungi. They work in synergy with the cytosolic NLRs [NOD (nucleotide binding and oligomerization domain)-like receptors] (which sense bacteria), RLRs [RIG-I (retinoic acid-inducible gene 1)-like receptors] (which sense viruses) and CLRs (C-type lectin receptors) (which sense fungi). All of these receptor families signal an increase in the expression of a range of immune and inflammatory genes. The structural architecture of these receptors is conserved, involving seven distinct domains: the LRR (leucine-rich repeat) domain, the TIR [Toll/IL (interleukin)-1 receptor] domain, the NBS (nucleotide-binding site), the CARD (caspase recruitment domain), the PYD (pyrin domain), the helicase domain and the CTLD (C-type lectin domain). Two other domains, the Ig domain and the ITAM (immunoreceptor tyrosine-based activation motif) domain also participate and are also found in antibodies and TCRs (T-cell receptors), key proteins in adaptive immunity. This total of nine domains can therefore be used to construct immune systems which are common to many, if not all, species, allowing us to speculate on the minimum requirement for a complex immune system in structural terms. These insights are important for our overall understanding of the regulation of immunity in health and disease.
The pharmacology of endosomal TLR agonists in viral disease
Authors: Averett D.R. , Fletcher S.P. , Li W. , Webber S.E. , Appleman J.R.
Published: January 2008

The discovery of endosomal TLRs (Toll-like receptors) and their natural ligands has accelerated efforts to exploit them for therapeutic benefit. Importantly, this was preceded by clinical exploration of agents now known to be endosomal TLR agonists. Clinical effects in viral disease have been reported with agonists of TLR3, TLR7, TLR7/8 and TLR9, and the TLR7 agonist imiquimod is marketed for topical use against warts, a papillomavirus disease. The observed pre-clinical and clinical profiles of agonists of each of these TLRs suggest induction of a multifaceted innate immune response, with biomarker signatures indicative of type 1 interferon induction. However, these agents differ in both their pharmaceutical characteristics and the cellular distribution of their target TLRs, suggesting that drugs directed to these targets will display differences in their overall pharmacological profiles.
Nod1 and Nod2 in innate immunity and human inflammatory disorders
Authors: Bourhis L. Le , Benko S. , Girardin S.E.
Published: January 2008

Nod (nucleotide-binding oligomerization domain) 1 and Nod2 are intracellular PRMs (pattern-recognition molecules) of the NLR (Nod-like receptor) family. These proteins are implicated in the detection of bacterial peptidoglycan and regulate pro-inflammatory pathways in response to bacteria by inducing signalling pathways such as NF-κB (nuclear factor κB) and MAPKs (mitogen-activated protein kinases). The Nod proteins act independently of the TLR (Toll-like receptor) cascade, but potently synergize with the latter to trigger innate immune responses to microbes. Most importantly, mutations in Nod2 have been shown to confer susceptibility to several chronic inflammatory disorders, including Crohn's disease, Blau syndrome and early-onset sarcoidosis, underscoring the role of Nod2 in inflammatory homoeostasis. This review summarizes the most recent findings in the field of Nod1 and Nod2 research.
Conserved and distinct aspects of the avian Toll-like receptor (TLR) system: implications for transmission and control of bird-borne zoonoses
Authors: Boyd A. , Philbin V.J. , Smith A.L.
Published: January 2008

This mini-review focuses on recent research with avian TLRs (Toll-like receptors), highlighting shared and distinct features compared with the more intensively studied mammalian TLR. These include the avian TLR repertoire and the response to various agonists. Studies with avian TLR can be applied to development of new approaches to control diseases of birds and is especially relevant to bird-borne zoonoses including avian influenza, Salmonella and Campylobacter.
Humanizing mismatch repair in yeast: towards effective identification of hereditary non-polyposis colorectal cancer alleles
Authors: Aldred P.M.R. , Borts R.H.
Published: January 2008

The correction of replication errors is an essential component of genetic stability. This is clearly demonstrated in humans by the observation that mutations in mismatch repair genes lead to HNPCC (hereditary non-polyposis colorectal cancer). This disease accounts for as many as 2–3% of colon cancers. Of these, most of them are in the two central components of mismatch repair, MLH1 (mutLhomologue 1) and MSH2 (mutShomologue 2). MLH1 and MSH2 function as a complex with two other genes PMS2 and MSH6. Mismatch repair genes, and the mechanism that ensures that incorrectly paired bases are removed, are conserved from prokaryotes to human. Thus yeast can serve as a model organism for analysing mutations/polymorphisms found in human mismatch repair genes for their effect on post-replicative repair. To date, this has predominantly been accomplished by making the analogous mutations in yeast genes. However, this approach is only useful for the most highly conserved regions. Here, we discuss some of the benefits and technical difficulties involved in expressing human genes in yeast. Modelling human mismatch repair in yeast will allow the assessment of any functional effect of novel polymorphisms found in patients diagnosed with colon cancers.
New parameters controlling the effect of temperature on enzyme activity
Authors: Daniel R.M. , Danson M.J. , Eisenthal R. , Lee C.K. , Peterson M.E.
Published: January 2008

Arising from careful measurements of the thermal behaviour of enzymes, a new model, the Equilibrium Model, has been developed to explain more fully the effects of temperature on enzymes. The model describes the effect of temperature on enzyme activity in terms of a rapidly reversible active–inactive (but not denatured) transition, revealing an additional and reversible mechanism for enzyme activity loss in addition to irreversible thermal inactivation at high temperatures. Two new thermal parameters, Teq and ΔHeq, describe the active–inactive transition, and enable a complete description of the effect of temperature on enzyme activity. We describe here the Model and its fit to experimental data, methods for the determination of the Equilibrium Model parameters, and the implications of the Model for the environmental adaptation and evolution of enzymes, and for biotechnology.
Pressure perturbation calorimetry, heat capacity and the role of water in protein stability and interactions
Authors: Cooper A. , Cameron D. , Jakus J. , Pettigrew G.W.
Published: January 2008

It is widely acknowledged, and usually self-evident, that solvent water plays a crucial role in the overall thermodynamics of protein stabilization and biomolecular interactions. Yet we lack experimental techniques that can probe unambiguously the nature of protein–water or ligand–water interactions and how they might change during protein folding or ligand binding. PPC (pressure perturbation calorimetry) is a relatively new technique based on detection of the heat effects arising from application of relatively small pressure perturbations (±5 atm; 1 atm=101.325 kPa) to dilute aqueous solutions of proteins or other biomolecules. We show here how this can be related to changes in solvation/hydration during protein–protein and protein–ligand interactions. Measurements of ‘anomalous’ heat capacity effects in a wide variety of biomolecular interactions can also be related to solvation effects as part of a quite fundamental principle that is emerging, showing how the apparently unusual thermodynamics of interactions in water can be rationalized as an inevitable consequence of processes involving the co-operative interaction of multiple weak interactions. This leads to a generic picture of the thermodynamics of protein folding stabilization in which hydrogen-bonding plays a much more prominent role than has been hitherto supposed.