bluuebunny/crossref_metadata_2025 huggingface dataset:
Ligand-induced cleavage and regulation of nuclear entry of Notch in Drosophila melanogaster embryos
Authors: Kidd Simon , Lieber Toby , Young Michael W.
Published: February 2008

Notch, a transmembrane protein found in a wide range of organisms, is a component of a pathway that mediates cell-fate decisions that involve intercellular communication. In this paper, we show that inDrosophila melanogaster, Notch (N) is processed in a ligand-dependent fashion to generate phosphorylated, soluble intracellular derivatives. Suppressor of Hairless [Su(H)] is predominantly associated with soluble intracellular N. It has been demonstrated by others that N has access to the nucleus, and we show that when tethered directly to DNA, the cytoplasmic domain of N can activate transcription. Conversely, a viral activator fused to Su(H) can substitute for at least some N functions during embryogenesis. We suggest that one function of soluble forms of N is to bind to Su(H), and in the nucleus, to act directly as a transcriptional transactivator of the latter protein. Although N has functional nuclear localization signals, the N/Su(H) complex accumulates in the cytoplasm and on membranes suggesting that its nuclear entry is regulated. Localization studies in cultured cells and embryos suggest that Su(H) plays a role in this regulation, with the relative levels of Delta, N and Su(H) determining whether a N/Su(H) complex enters the nucleus.
Drosophila Cyclin B3 is required for female fertility and is dispensable for mitosis like Cyclin B
Authors: Jacobs Henning W. , Knoblich Jürgen A. , Lehner Christian F.
Published: February 2008

Cyclin B3 has been conserved during higher eukaryote evolution as evidenced by its identification in chicken, nematodes, and insects. We demonstrate that Cyclin B3 is present in addition to Cyclins A and B in mitotically proliferating cells and not detectable in endoreduplicating tissues of Drosophila embryos. Cyclin B3 is coimmunoprecipitated with Cdk1(Cdc2) but not with Cdk2(Cdc2c). It is degraded abruptly during mitosis like Cyclins A and B. In contrast to these latter cyclins, which accumulate predominantly in the cytoplasm during interphase, Cyclin B3 is a nuclear protein. Genetic analyses indicate functional redundancies. Double and triple mutant analyses demonstrate that Cyclins A, B, and B3 cooperate to regulate mitosis, but surprisingly single mutants reveal that neither Cyclin B3 nor Cyclin B is required for mitosis. However, both are required for female fertility and Cyclin B also for male fertility.
Reprogramming of early embryonic blastomeres into endodermal progenitors by a Caenorhabditis elegans GATA factor
Authors: Zhu Jiangwen , Fukushige Tetsunari , McGhee James D. , Rothman Joel H.
Published: February 2008

The END-1 GATA factor has been implicated in specifying endoderm in Caenorhabditis elegans and is the earliest known zygotic protein expressed in the lineage of E, the clonal endoderm progenitor. We report that ubiquitous end-1 expression during a critical period in embryogenesis causes all non-endodermal lineages to produce endoderm instead of ectoderm and/or mesoderm. END-1 expression bypasses the requirement for maternal SKN-1 and the maternal Wnt signaling pathway in endoderm formation. This suggests that a primary function of these maternal factors is to regulate zygoticend-1 expression, which is then sufficient to initiate the entire program for endoderm development.
The RNA cleavage activity of RNA polymerase III is mediated by an essential TFIIS-like subunit and is important for transcription termination
Authors: Chédin Stéphane , Riva Michel , Schultz Patrick , Sentenac André , Carles Christophe
Published: February 2008

Budding yeast RNA polymerase III (Pol III) contains a small, essential subunit, named C11, that is conserved in humans and shows a strong homology to TFIIS. A mutant Pol III, heterocomplemented withSchizosaccharomyces pombe C11, was affected in transcription termination in vivo. A purified form of the enzyme (Pol IIIΔ), deprived of C11 subunit, initiated properly but ignored pause sites and was defective in termination. Remarkably, Pol III Δ lacked the intrinsic RNA cleavage activity of complete Pol III. In vitro reconstitution experiments demonstrated that Pol III RNA cleavage activity is mediated by C11. Mutagenesis in C11 of two conserved residues, which are critical for the TFIIS-dependent cleavage activity of Pol II, is lethal. Immunoelectron microscopy data suggested that C11 is localized on the mobile thumb-like stalk of the polymerase. We propose that C11 allows the enzyme to switch between an RNA elongation and RNA cleavage mode and that the essential role of the Pol III RNA cleavage activity is to remove the kinetic barriers to the termination process. The integration of TFIIS function into a specific Pol III subunit may stem from the opposite requirements of Pol III and Pol II in terms of transcript length and termination efficiency.
The Elongin BC complex interacts with the conserved SOCS-box motif present in members of the SOCS, ras, WD-40 repeat, and ankyrin repeat families
Authors: Kamura Takumi , Sato Shigeo , Haque Dewan , Liu Li , Kaelin William G. , Conaway Ronald C. , Conaway Joan Weliky
Published: February 2008

The Elongin BC complex was identified initially as a positive regulator of RNA polymerase II (Pol II) elongation factor Elongin A and subsequently as a component of the multiprotein von Hippel-Lindau (VHL) tumor suppressor complex, in which it participates in both tumor suppression and negative regulation of hypoxia-inducible genes. Elongin B is a ubiquitin-like protein, and Elongin C is a Skp1-like protein that binds to a BC-box motif that is present in both Elongin A and VHL and is distinct from the conserved F-box motif recognized by Skp1. In this report, we demonstrate that the Elongin BC complex also binds to a functional BC box present in the SOCS box, a sequence motif identified recently in the suppressor of cytokine signaling-1 (SOCS-1) protein, as well as in a collection of additional proteins belonging to the SOCS, ras, WD-40 repeat, SPRY domain, and ankyrin repeat families. In addition, we present evidence (1) that the Elongin BC complex is a component of a multiprotein SOCS-1 complex that attenuates Jak/STAT signaling by binding to Jak2 and inhibiting Jak2 kinase, and (2) that by interacting with the SOCS box, the Elongin BC complex can increase expression of the SOCS-1 protein by inhibiting its degradation. These results suggest that Elongin BC is a multifunctional regulatory complex capable of controlling multiple pathways in the cell through interaction with a short degenerate sequence motif found in many different proteins.
The Vestigial and Scalloped proteins act together to directly regulate wing-specific gene expression in Drosophila
Authors: Halder Georg , Polaczyk Patricia , Kraus Mary Ellen , Hudson Angela , Kim Jaeseob , Laughon Allen , Carroll Sean
Published: February 2008

A small number of major regulatory (selector) genes have been identified in animals that control the development of particular organs or complex structures. In Drosophila, the vestigialgene is required for wing formation and is able to induce wing-like outgrowths on other structures. However, the molecular function of the nuclear Vestigial protein, which bears no informative similarities to other proteins, was unknown. Here, we show that Vestigial requires the function of the Scalloped protein, a member of the TEA family of transcriptional regulators, to directly activate the expression of genes involved in wing morphogenesis. Genetic and molecular analyses reveal that Vestigial regulates wing identity by forming a complex with the Scalloped protein that binds sequence specifically to essential sites in wing-specific enhancers. These enhancers also require the direct inputs of signaling pathways, and the response of an enhancer can be switched to another pathway through changes in signal-transducer binding sites. Combinatorial regulation by selector proteins and signal transducers is likely to be a general feature of the tissue-specific control of gene expression during organogenesis.
Mechanisms of developmental control of transcription in the murine α- and β-globin loci
Authors: Trimborn Tolleiv , Gribnau Joost , Grosveld Frank , Fraser Peter
Published: February 2008

We have characterized mRNA expression and transcription of the mouseα- and β-globin loci during development. S1 nuclease and primary transcript in situ hybridization analyses demonstrate that all seven murine globin genes (ζ, α1,α2, εy,βH1, βmaj, andβmin) are transcribed during primitive erythropoiesis, however transcription of the ζ,εy, and βH1 genes is restricted to the primitive erythroid lineage. Transcription of theβmaj and βmin genes in primitive cells is EKLF-dependent demonstrating EKLF activity in embryonic red cells. Novel kinetic analyses suggest that multigene expression in the β locus occurs via alternating single-gene transcription whereas coinitiation cannot be ruled out in the α locus. Transcriptional activation of the individual murine β genes in primitive cells correlates inversely with their distance from the locus control region, in contrast with the human β locus in which the adult genes are only activated in definitive erythroid cells. The results suggest that the multigene expression mechanism of alternating transcription is evolutionarily conserved between mouse and humanβ globin loci but that the timing of activation of the adult genes is altered, indicating important fundamental differences in globin gene switching.
Identification of a novel mechanism of regulation of Ah (dioxin) receptor function
Authors: Mimura Junsei , Ema Masatsugu , Sogawa Kazuhiro , Fujii-Kuriyama Yoshiaki
Published: February 2008

Ah receptor (AhR) is a ligand-activated transcription factor that mediates pleiotropic effects of environmental pollutants such as 2,3,7,8-tetrachlorodibenzo-p-dioxin on host animals. In addition to induction of drug-metabolizing enzymes, the liganded AhR complex was found to activate gene expression of a factor designated AhR repressor (AhRR), which inhibits AhR function by competing with AhR for dimerizing with Arnt and binding to the XRE sequence. Thus, AhR and AhRR form a regulatory circuit in the xenobiotic signal transduction pathway and provide a novel mechanism of regulation of AhR function that may determine tissue-specific sensitivity to environmental pollutants.
Blockade of IP3-mediated SK channel signaling in the rat medial prefrontal cortex improves spatial working memory
Authors: Brennan Avis R. , Dolinsky Beth , Vu Mai-Anh T. , Stanley Marion , Yeckel Mark F. , Arnsten Amy F.T.
Published: February 2008

Planning and directing thought and behavior require the working memory (WM) functions of prefrontal cortex. WM is compromised by stress, which activates phosphatidylinositol (PI)-mediated IP3-PKC intracellular signaling. PKC overactivation impairs WM operations and in vitro studies indicate that IP3 receptor (IP3R)-evoked calcium release results in SK channel-dependent hyperpolarization of prefrontal neurons. However, the effects of IP3R signaling on prefrontal function have not been investigated. The present findings demonstrate that blockade of IP3R or SK channels in the prefrontal cortex enhances WM performance in rats, suggesting that both arms of the PI cascade influence prefrontal cognitive function.
Intersubunit linker length as a modifier of protein stability: Crystal structures and thermostability of mutant TRAP
Authors: Watanabe Masahiro , Mishima Yumiko , Yamashita Ichiro , Park Sam‐Yong , Tame Jeremy R.H. , Heddle Jonathan G.
Published: February 2008

The ability of proteins to self‐assemble into complex, functional nanoscale structures is expected to become of significant use in the manufacture of artificial nanodevices with a wide range of novel applications. The bacterial protein TRAP has potential uses as a nanoscale component as it is ring‐shaped, with a central, modifiable cavity. Furthermore, it can be engineered to make a ring of 12‐fold symmetry, which is advantageous for packing into two‐dimensional arrays. The 12mer form of TRAP is made by linking multiple subunits together on the same polypeptide, but the usefulness of the 12mers described to date is limited by their poor stability. Here we show that, by altering the length of the peptide linker between subunits, the thermostability can be significantly improved. Since the subunit interfaces of the different 12mers are essentially identical, stabilization arises from the reduction of strain in the linkers. Such a simple method of controlling the stability of modular proteins may have wide applications, and demonstrates the lack of absolute correlation between interactions observable by crystallography and the internal energy of a complex.
Rational design of a novel calcium‐binding site adjacent to the ligand‐binding site on CD2 increases its CD48 affinity
Authors: Jones Lisa M. , Yang Wei , Maniccia Anna W. , Harrison Alice , van der Merwe P. Anton , Yang Jenny J.
Published: February 2008

Electrostatic interactions are important for molecular recognition processes including Ca2+‐binding and cell adhesion. To understand these processes, we have successfully introduced a novel Ca2+‐binding site into the non‐Ca2+‐dependent cell adhesion protein CD2 using our criteria that are specifically tailored to the structural and functional properties of the protein environment and charged adhesion surface. This designed site with ligand residues exclusively from the β‐sheets selectively binds to Ca2+ and Ln3+ over other mono‐ and divalent cations. While Ca2+ and Ln3+ binding specifically alters the local environment of the designed Ca2+‐binding site, the designed protein undergoes a significantly smaller conformation change compared with those observed in naturally occurring Ca2+‐binding sites that are composed of at least part of the flexible loop and helical regions. In addition, the CD2–CD48‐binding affinity increased approximately threefold after protein engineering, suggesting that the cell adhesion of CD2 can be modulated by altering the local electrostatic environment. The study provides site‐specific information for regulating cell adhesion within CD2 and gives insight into the structural factors required for Ca2+‐modulated biological processes.
Association of genetic polymorphisms inSLCO1B3andABCC2with docetaxel‐induced leukopenia
Authors: Kiyotani Kazuma , Mushiroda Taisei , Kubo Michiaki , Zembutsu Hitoshi , Sugiyama Yuichi , Nakamura Yusuke
Published: February 2008

Despite long‐term clinical experience with docetaxel, unpredictable severe adverse reactions remain an important determinant for limiting the use of the drug. To identify a genetic factor(s) determining the risk of docetaxel‐induced leukopenia/neutropenia, we selected subjects who received docetaxel chemotherapy from samples recruited at BioBank Japan, and conducted a case–control association study. We genotyped 84 patients, 28 patients with grade 3 or 4 leukopenia/neutropenia, and 56 with no toxicity (patients with grade 1 or 2 were excluded), for a total of 79 single nucleotide polymorphisms (SNPs) in seven genes possibly involved in the metabolism or transport of this drug:CYP3A4,CYP3A5,ABCB1,ABCC2,SLCO1B3,NR1I2, andNR1I3. Since one SNP inABCB1, four SNPs inABCC2, four SNPs inSLCO1B3, and one SNP inNR1I2showed a possible association with the grade 3 leukopenia/neutropenia (P‐value of <0.05), we further examined these 10 SNPs using 29 additionally obtained patients, 11 patients with grade 3/4 leukopenia/neutropenia, and 18 with no toxicity. The combined analysis indicated a significant association of rs12762549 inABCC2(P = 0.00022) and rs11045585 inSLCO1B3(P = 0.00017) with docetaxel‐induced leukopenia/neutropenia. When patients were classified into three groups by the scoring system based on the genotypes of these two SNPs, patients with a score of 1 or 2 were shown to have a significantly higher risk of docetaxel‐induced leukopenia/neutropenia as compared to those with a score of 0 (P = 0.0000057; odds ratio [OR], 7.00; 95% CI [confidence interval], 2.95–16.59). This prediction system correctly classified 69.2% of severe leukopenia/neutropenia and 75.7% of non‐leukopenia/neutropenia into the respective categories, indicating that SNPs inABCC2andSLCO1B3may predict the risk of leukopenia/neutropenia induced by docetaxel chemotherapy. (Cancer Sci2008; 99: 967–972)
Pharmacokinetic interactions of efavirenz and voriconazole in healthy volunteers
Authors: Damle Bharat , LaBadie Robert , Crownover Penelope , Glue Paul
Published: February 2008

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

• Efavirenz 400 mg q24 h reduces exposure to voriconazole 200 mg q12 h when the two drugs are co‐administered.

• Furthermore, voriconazole increases the systemic exposure of efavirenz.

• Co‐administration was therefore initially contraindicated.

WHAT THIS STUDY ADDS

• The doses of efavirenz and voriconazole can be adjusted to provide adequate exposure to both drugs when the two are co‐administered, without compromising safety.

• Appropriate adjustment of doses for both drugs may thus represent an alternative to a mere contraindication.

AIMS

Co‐administration of standard‐dose voriconazole and efavirenz results in a substantial decrease in voriconazole levels, while concurrently increasing efavirenz levels. Hence, concomitant use of standard doses of these drugs was initially contraindicated. This study assessed different dose combinations of efavirenz and voriconazole, with the goal of attaining a dose combination that provides systemic exposures similar to standard‐dose monotherapy with each drug.

METHODS

This was an open‐label, four‐treatment, multiple‐dose, fixed‐sequence study in 16 healthy males. Steady‐state pharmacokinetics were assessed following two test treatments (voriconazole 300 mg q12 h + efavirenz 300 mg q24 h and voriconazole 400 mg q12 h + efavirenz 300 mg q24 h) and compared with standard‐dose monotherapy (voriconazole 200 mg q12 h or efavirenz 600 mg q24 h).

RESULTS

Dose adjustment to voriconazole 300 mg q12 h with efavirenz 300 mg q24 h decreased voriconazole area under the concentration–time curve (AUCτ) and maximum concentration (Cmax), with changes of −55% [90% confidence interval (CI) −62, −45] and −36% (90% CI −49, −21), respectively, when compared with monotherapy. Voriconazole 400 mg q12 h plus efavirenz 300 mg q24 h decreased voriconazole AUCτ (−7%; 90% CI −23, 13) and increased Cmax (23%; 90% CI −1, 53), while increasing efavirenz AUCτ (17%; 90% CI 6, 29) and not changing Cmax when compared with the respective monotherapy regimens. No serious adverse events were observed with voriconazole plus efavirenz.

CONCLUSIONS

When co‐administered, voriconazole dose should be increased to 400 mg q12 h and efavirenz dose decreased to 300 mg q24 h in order to provide systemic exposures similar to standard‐dose monotherapy.
The different effects of itraconazole on the pharmacokinetics of fexofenadine enantiomers
Authors: Tateishi Tomonori , Miura Masatomo , Suzuki Toshio , Uno Tsukasa
Published: February 2008

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

• Recently, we have shown that the plasma concentration ofR‐fexofenadine is greater than that of theS‐enantiomer.

• Although itraconazole co‐administration is known to increase the bioavailability of a racemic mixture of fexofenadine, little is known about the stereoselective inhibition of P‐gp activity by itraconazole.

WHAT THIS STUDY ADDS

• This study indicates that the stereoselective pharmacokinetics of fexofenadine are due to P‐gp‐mediated transport and its stereoselectivity is altered by itraconazole, a an inhibitor of P‐gp.

AIMS

The aim of this study was to determine the inhibitory effect of itraconazole, a P‐glycoprotein (P‐gp) inhibitor, on the stereoselective pharmacokinetics of fexofenadine.

METHODS

A two‐way double‐blind, placebo‐controlled crossover study was performed with a 2‐week washout period. Twelve healthy volunteers received either itraconazole 200 mg or matched placebo in a randomized fashion with a single oral dose of fexofenadine 60 mg simultaneously. The plasma concentrations and the amount of urinary excretion (Ae) of fexofenadine enantiomers were measured up to 24 h after dosing.

RESULTS

After placebo administration, mean AUC(0,24 h) ofS‐ andR‐fexofenadine was 474 ng ml−1 h (95% CI 311, 638) and 798 ng ml−1 h (95% CI 497, 1101), respectively. Itraconazole affected the pharmacokinetic parameters ofS‐fexofenadine more, and increased AUC(0,24 h) ofS‐fexofenadine andR‐fexofenadine by 4.0‐fold (95% CI of differences 2.8, 5.3;P < 0.001) and by 3.1‐fold (95% CI of differences 2.2, 4.0;P = 0.014), respectively, and Ae(0,24 h) ofS‐fexofenadine andR‐fexofenadine by 3.6‐fold (95% CI of differences 2.6, 4.5;P < 0.001) and by 2.9‐fold (95% CI of differences 2.1, 3.8;P < 0.001), respectively. Additionally, theR : Sratio for AUC(0,24 h) and Ae(0,24 h) were significantly reduced in the itraconazole phase, whiletmax,t1/2and renal clearance were constant during the study.

CONCLUSIONS

This study indicates that the stereoselective pharmacokinetics of fexofenadine are due to P‐gp‐mediated transport and its stereoselectivity is altered by itraconazole, a P‐gp inhibitor. However, further study will be needed because the different affinities of the two enantiomers for P‐gp have not been supported byin vitrostudies.
The recovery time‐course of CYP3A after induction by St John's wort administration
Authors: Imai Hiromitsu , Kotegawa Tsutomu , Tsutsumi Kimiko , Morimoto Takuya , Eshima Nobuoki , Nakano Shigeyuki , Ohashi Kyoichi
Published: February 2008

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

• St John's wort causes the induction of CYP3A. Little is known about how long the effect remains after cessation of St John's wort.

WHAT THIS STUDY ADDS

• The in vivo CYP3A activity returns progressively to the basal level approximately 1 week after cessation of St John's wort administration

AIMS

To examine the recovery time course of CYP3A after enzyme induction by St John's wort administration.

METHODS

The subjects were 12 healthy men, aged 20–33 years. On the first day, they received an oral dose of midazolam 5 mg without St John's wort (day −14). From the next day, they took St John's wort for 14 days. On the last day of St John's wort treatment (day 0) and 3 and 7 days after completion of St John's wort treatment (days 3 and 7), they received the same dose of midazolam. On each day, blood samples were obtained until 8 h after midazolam administration. Plasma concentrations of midazolam were measured by HPLC. Pharmacokinetic parameters of midazolam were determined using noncompartmental analysis.

RESULTS

Apparent oral clearance of midazolam was significantly increased after St John's wort administration from 65.3 ± 8.4 l h−1 (day −14) to 86.8 ± 17.3 l h−1 (day 0). It returned to the control level 7 days after the completion of St John's wort (day 7, 59.7 ± 3.8 l h−1). No significant difference in the elimination half‐life between the four periods of the study was observed. The changes in apparent oral clearance after St John's wort discontinuation indicated that CYP3A activity recovers from enzyme induction with an estimated half‐life of 46.2 h.

CONCLUSIONS

CYP3A activity induced by St John's wort administration progressively returns to the basal level after approximately 1 week. This finding may provide useful information to avoid clinically significant interactions of St John's wort with CYP3A substrates.
Dual‐porosity modelling of the pore structure and transport properties of a contaminated soil
Authors: Tsakiroglou C. D. , Ioannidis M. A.
Published: February 2008

We have developed a new method to characterize the pore structure of mineral soils. We combined data from the analysis of back‐scattered scanning electron microscope (BSEM) images of resin‐impregnated pore‐casts, and mercury intrusion porosimetry (MIP) data, with analytical percolation models and inverse modeling algorithms. The pore space is regarded as a dual‐pore network consisting of a primary Euclidean pore‐and‐throat network and a secondary, fractal, pore system that is accessed through primary pores. The digitized 2‐D BSEM images of resin‐impregnated soil samples are employed to determine the autocorrelation function. The Fourier transform of this function provides the small‐angle neutron scattering (SANS) intensity function, which is extended by using the surface fractal dimension obtained from high‐pressure MIP data. Inversion of the extended scattering intensity function produces the volume‐based radius distribution function of spherical pore bodies (PBRD). The complete volume‐based PBRD is fitted with a composite number‐based PBRD composed of a lognormal primary PBRD and a power (fractal) secondary PBRD with upper and lower cut‐offs. Based on the concepts of invasion percolation, an analytic mathematical model that describes Hg intrusion into dual pore networks is developed. The complete PBRD and pore‐throat radius distribution (PTRD) functions of the primary network along with the drainage accessibility functions (DAFs) of the primary and secondary pore networks are estimated with inverse modelling of the Hg intrusion curve. Based on critical path analysis of percolation theory, approximate analytical relationships are developed to calculate explicitly the absolute permeability and electrical formation factor from the geometrical and topological parameters of the primary pore network. The method is demonstrated with application to four soil samples.
Changes in shrinkage of restored soil caused by compaction beneath heavy agricultural machinery
Authors: Schäffer B. , Schulin R. , Boivin P.
Published: February 2008

Compaction is a major cause of soil degradation. It affects not only the porosity of the soil, but also the soil’s hydrostructural stability. Soil that is restored after temporary removal is particularly sensitive to compaction. We investigated the effects of trafficking with a heavy combine harvester on the shrinkage behaviour of a restored soil that had been gently cultivated for several years. We tested the hypothesis that compaction decreases the hydrostructural stability of restored soil by analysing simultaneously measured shrinkage and water retention curves of undisturbed soil samples. Shrinkage strongly depended on clay and organic carbon content. Taking account of this influence and normalizing the shrinkage parameters with respect to these soil properties, we found pronounced effects of trafficking on shrinkage. Ten passes with the combine harvester decreased the structural porosity by about 40% at maximum swelling and by about 30% at the shrinkage limit and increased the bulk density by 8% at maximum swelling and by 10% at the shrinkage limit, but did not significantly affect the porosity of the soil plasma. Moreover, trafficking modified shrinkage, increasing the slopes of the shrinkage curve in the basic and structural shrinkage domains by about 30% and more than 150% after 10 passes, respectively. Evidently the aggregate structure was strongly destabilized. The results indicate that the hydrostructural stability of the soil was still very sensitive to compaction by trafficking even 5 years after restoration. The analysis of shrinkage seemed well suited for the assessment of compaction effects on soil structure.
A mechanistic model of benthos community dynamics in the River Sihl, Switzerland
Authors: SCHUWIRTH NELE , KÜHNI MARTIN , SCHWEIZER STEFFEN , UEHLINGER URS , REICHERT PETER
Published: February 2008

1. Most of the existing river ecosystem models describe only part of the ecosystem, have site‐specific features, and lack an adequate treatment of uncertainty.

2. We developed a dynamic model of the functional groups of non‐filamentous and filamentous algae, scrapers, collector‐gatherers and predators of the benthos community in rivers. This model is based on relatively universal model formulations and is intended to be a first submodel for a more complete model of the river ecosystem and the biogeochemical processes in the river.

3. The model was tested for the River Sihl in Switzerland. To take advantage of prior knowledge of model parameters, to account for their non‐identifiability given the measured data, and to consider uncertainty of model parameters and results, Bayesian inference was used to update the prior probability distribution of the model parameters.

4. The calibrated model showed very good agreement of model results with measured data. None of the posterior parameter marginals showed a conflict with the prior. Some posterior marginals (specific growth rates of the functional groups, specific death rates, parameters characterizing self‐ and mutual shading of algae, and the critical level of discharge for catastrophic loss) were significantly narrower than the priors, indicating considerable gain of information from the measurements. For other parameters (half‐saturation concentrations of algae and invertebrate growth, parameters characterizing temperature dependence of invertebrate growth rates, colonization rates and most coefficients of catastrophic loss), no significant information could be gained from the data. This clearly demonstrated the need for a Bayesian analysis.

5. The model seems to be a promising step towards a more comprehensive model of the river ecosystem and the biogeochemical processes in the river. However, more efforts are required: In particular, extension of the model by a description of the dynamics of benthic biofilms and nutrient dynamics and application of the (extended) model to more rivers to learn about the dependence of model parameters on river characteristics. The difficulty of finding adequate data sets for testing such and extended models demonstrates the need for comprehensive measurement campaigns that get information of periphyton, benthic invertebrates, benthic biofilms, suspended and sedimented organic particles, suspended organisms and nutrient concentrations and transformation rates in the water column.
Caspase‐3‐dependent phagocyte death during systemic Salmonella enterica serovar Typhimurium infection of mice
Authors: Grant Andrew J. , Sheppard Mark , Deardon Rob , Brown Sam P. , Foster Gemma , Bryant Clare E. , Maskell Duncan J. , Mastroeni Pietro
Published: February 2008

Growth of Salmonella enterica in mammalian tissues results from continuous spread of bacteria to new host cells. Our previous work indicated that infective S. enterica are liberated from host cells via stochastic necrotic burst independently of intracellular bacterial numbers. Here we report that liver phagocytes can undergo apoptotic caspase‐3‐mediated cell death in vivo, with apoptosis being a rare event, more prevalent in heavily infected cells. The density‐dependent apoptotic cell death is likely to constitute an alternative mechanism of bacterial spread as part of a bet‐hedging strategy, ensuring an ongoing protective intracellular environment in which some bacteria can grow and persist.
Confocal immunolocalization of VE‐cadherin‐ and CXC chemokine‐expressing endothelial cells in periapical granulomas
Authors: Takeichi O. , Hama S. , Iwata K. , Ito K.
Published: February 2008

Aim  To determine whether endothelial cells (ECs) in periapical granulomas can express vascular endothelial (VE)‐cadherin, CXCL8 and CXCL10 by examining with two‐colour confocal laser scanning microscope.

Methodology  Periapical lesions were surgically removed from patients with chronic periapical periodontitis (n = 20), and the paraffin‐embedded sections were prepared after being fixed with cold acetone. The 7‐μm‐thick sections were stained with haematoxylin–eosin and then examined pathologically using a light microscope. The lesions diagnosed as periapical granulomas (17 specimens) were analysed further using immunofluorescence and antibodies specific for human VE‐cadherin, CXCL8, and CXCL10. The slides were carefully examined using a confocal laser scanning microscope. The numbers of positive ECs were counted, and the comparison between VE‐cadherin‐positive ECs and CXCL8 or CXCL10 was assessed statistically using one‐way ANOVA followed by a Student–Newman–Keuls test.

Results  The expression of CXCL8 and CXCL10 by ECs was detected in 60.4 ± 13.4 and 67.2 ± 13.9%, respectively. However, the percentage of VE‐cadherin‐expressing ECs was 40.4 ± 10.5%, which was significantly lower (P < 0.01) than CXCL8 and CXCL10‐expressing ECs. Two‐colour immunofluorescence staining revealed that ECs co‐expressed VE‐cadherin and CXCL8 (37.4 ± 14.1%) or CXCL10 (39.1 ± 13.8%).

Conclusions  VE‐cadherin expression in ECs was lower than CXCL8 and CXCL10, suggesting that inflamed ECs in periapical granulomas could increase vascular permeability and that leukocyte chemotaxis mediated by ECs might occur. These findings may suggest the possibility that ECs could play a pivotal role in cell recruitment in periapical granulomas.
Electric pulp testing: a review
Authors: Lin J. , Chandler N. P.
Published: February 2008

Electric pulp testing (EPT) has been available for more than a century and used in dental practices worldwide. This article provides an overview of this diagnostic aid. The PubMed database from 1953 was used initially; the reference list for pulp testing featured 1071 articles, and for EPT identified 121 papers. A forward search was undertaken on these articles and using selected author names. Potentially relevant material was also sought in contemporary endodontic texts, while older textbooks on endodontics, operative dentistry and pain revealed historic information and primary research not found electronically. A short account of the innervation of the pulp is followed by an historic overview. Clinical considerations discussed include tooth isolation, glove wearing and tester electrode placement. Orthodontic treatment, pacemaker wearing and patient medications are considered. Research applications are also discussed. While EPT is valuable, no single pulp testing technique can reliably diagnose all pulp conditions. Careful collection of patient history regarding the problem tooth and prudent use of appropriate radiographs are also helpful. The shortcomings of electric tests, especially in the case of immature and concussed teeth, must be understood. The demeanour of the patient and the responses given by control teeth also require careful consideration.
Factors affecting the timing of teething in healthy Turkish infants: a prospective cohort study
Authors: SAHIN FIGEN , CAMURDAN AYSU DUYAN , CAMURDAN M. ORHUN , OLMEZ AYSEGÜL , OZNURHAN FATIH , BEYAZOVA UFUK
Published: February 2008

Background.  Teething is a developmental process and occurs over a broad chronological age range.

Objective.  The objective of this study was to evaluate the effects of feeding pattern and growth parameters on teething time of healthy infants.

Methods.  A total of 1200 term newborn infants followed up in Gazi University well‐child clinic infants were evaluated, and their growth parameters, feeding patterns, and timing of the eruption of the first tooth were noted. The routine visit times of the clinic were chosen as the cut‐off values for teeth eruption for logistic regression analysis for investigating factors that determine the timing of teeth eruption.

Results.  Timing of the eruption of the first tooth ranged from 4 to 13 months. On the sixth month visit, 24.3%, and on the ninth month visit 84.5% of all infants had at least one tooth. Height‐adjusted weight and height percentiles being less than 50, being fed by cow's milk or by formula in the first year, were independent factors negatively influencing teeth eruption by the sixth month, while all but height‐adjusted weight percentiles being less than 50 had negative impact on tooth eruption by the ninth month.

Conclusion.  Growth parameters and feeding pattern may be determinants of the timing of teeth eruption in healthy infants.
In vitro pulp chamber temperature rise from irradiation and exotherm of flowable composites
Authors: BAROUDI KUSAI , SILIKAS NICK , WATTS DAVID C.
Published: February 2008

Objective.  The aim of this study was to investigate the pulpal temperature rise induced during the polymerization of flowable and non‐flowable composites using light‐emitting diode (LED) and halogen (quartz–tungsten–halogen) light‐curing units (LCUs).

Methods.  Five flowable and three non‐flowable composites were examined. Pulpal temperature changes were recorded over 10 min in a sample primary tooth by a thermocouple. A conventional quartz–tungsten–halogen source and two LEDs, one of which was programmable, were used for light curing the resin composites. Three repetitions per material were made for each LCU.

Results.  There was a wide range of temperature rises among the materials (P < 0.05). Temperature rises ranged between 1.3 °C for Filtek Supreme irradiated by low‐power LED and 4.5 °C for Grandio Flow irradiated by high‐power LED. The highest temperature rises were observed with both the LED high‐power and soft‐start LCUs. The time to reach the exothermic peak varied significantly between the materials (P < 0.05).

Conclusions.  Pulpal temperature rise is related to both the radiant energy output from LCUs and the polymerization exotherm of resin composites. A greater potential risk for heat‐induced pulp damage might be associated with high‐power LED sources. Flowable composites exhibited higher temperature rises than non‐flowable materials, because of higher resin contents.
Acupuncture in Polycystic Ovary Syndrome: Current Experimental and Clinical Evidence
Authors: Stener‐Victorin E. , Jedel E. , Mannerås L.
Published: February 2008

This review describes the aetiology and pathogenesis of polycystic ovary syndrome (PCOS) and evaluates the use of acupuncture to prevent and reduce symptoms related with PCOS. PCOS is the most common female endocrine disorder and it is strongly associated with hyperandrogenism, ovulatory dysfunction and obesity. PCOS increases the risk for metabolic disturbances such as hyperinsulinaemia and insulin resistance, which can lead to type 2 diabetes, hypertension and an increased likelihood of developing cardiovascular risk factors and impaired mental health later in life. Despite extensive research, little is known about the aetiology of PCOS. The syndrome is associated with peripheral and central factors that influence sympathetic nerve activity. Thus, the sympathetic nervous system may be an important factor in the development and maintenance of PCOS. Many women with PCOS require prolonged treatment. Current pharmacological approaches are effective but have adverse effects. Therefore, nonpharmacological treatment strategies need to be evaluated. Clearly, acupuncture can affect PCOS via modulation of endogenous regulatory systems, including the sympathetic nervous system, the endocrine and the neuroendocrine system. Experimental observations in rat models of steroid‐induced polycystic ovaries and clinical data from studies in women with PCOS suggest that acupuncture exert long‐lasting beneficial effects on metabolic and endocrine systems and ovulation.
Jacques Benoit Lecture: The Neuroendocrine View of the Angiotensin and Apelin Systems
Authors: Llorens‐Cortes C. , Kordon C.
Published: February 2008

The hyperactivity of the brain renin–angiotensin system (RAS) has been implicated in the development and maintenance of hypertension in several types of experimental and genetic hypertension animal models. Among the main bioactive peptides of the brain RAS, angiotensin (Ang) II and Ang III display the same affinity for type 1 and type 2 Ang II receptors. Both peptides, injected intracerebroventricularly, similarly increase arginine vasopressin (AVP) release and blood pressure (BP); however, because Ang II is converted in vivo to Ang III, the identity of the true effector is unknown. We review new insights into the predominant role of brain Ang III in the control of BP, underlining the fact that brain aminopeptidase A (APA), the enzyme generating brain Ang III, may therefore be an interesting candidate target for the treatment of hypertension. This justifies the development of potent systemically active APA inhibitors, such as RB150, as prototypes of a new class of antihypertensive agents for the treatment of certain forms of hypertension. We also searched for a putative angiotensin receptor subtype specific for Ang III and isolated a seven transmembrane‐domain G protein‐coupled receptor corresponding to the receptor for apelin, a newly‐discovered peptide isolated from bovine stomach. Apelin and its receptor are expressed in magnocellular vasopressinergic neurones in the hypothalamus. The central injection of apelin in lactating rats decreases the phasic electrical activity of vasopressinergic neurones and the systemic secretion of AVP, inducing water diuresis. Apelin is therefore a natural inhibitor of the antidiuretic effect of AVP. In addition, systemic administration of apelin decreases BP, improves cardiac contractility and reduces cardiac loading. The development of nonpeptide agonists of the apelin receptor may provide new therapeutic tools for treating water retention, hyponatraemia and cardiovascular diseases. Angiotensins and apelin thus exert opposing but complementary effects, and are thereby determinant for the maintenance of body fluid homeostasis and cardiovascular functions.
The Effect of AMP‐Activated Kinase Activation on Gonadotrophin‐Releasing Hormone Secretion in GT1‐7 Cells and its Potential Role in Hypothalamic Regulation of the Oestrous Cyclicity in Rats
Authors: Coyral‐Castel S. , Tosca L. , Ferreira G. , Jeanpierre E. , Rame C. , Lomet D. , Caraty A. , Monget P. , Chabrolle C. , Dupont J.
Published: February 2008

Hypothalamic AMP‐activated kinase (AMPK) is a key regulator of food intake in mammals. Its role in reproduction at the central level and, more precisely, in gonadotrophin‐releasing hormone (GnRH) release has never been investigated. We showed that each subunit of AMPK is present in immortalised GnRH neurones (GT1‐7 cells). Treatment with 5‐aminoimidazole‐4‐carboxamide‐1‐β‐d‐ribonucleoside (AICAR) and metformin, two activators of AMPK, increased dose‐dependent and time‐dependent phosphorylation of AMPKα atThr172 in GT1‐7 cells. Phosphorylation of acetyl‐coenzyme A carboxylase at ser79 also increased. Treatment with AICAR (5 mm) or metformin (5 mm) for 4 h inhibited GnRH release in the presence or absence of GnRH (10−8 m). Specific AMPK inhibitor compound C completely eliminated the effects of AICAR or metformin on GnRH release. Finally, we determined the central effects of AICAR in vivo on food intake and oestrous cyclicity. Ten‐week‐old female rats received a 50 μg AICAR or a saline i.c.v. injection. We detected increased AMPK and acetyl‐CoA carboxylase phosphorylation, specifically in the hypothalamus, 30 min after AICAR injection. Food intake was significantly higher (P < 0.05) in animals treated with AICAR than in animals injected with saline, 24 h after injection. This effect was abolished after 1 week. Moreover, during the 4 weeks following injection, the interval between two oestrous stages was significantly lower in the AICAR group than in the saline group. Our findings suggest that AMPK activation may act directly at the hypothalamic level to affect fertility by modulating GnRH release and oestrous cyclicity.
Hypoxia‐Induced Apoptotic Cell Death is Prevented by Oestradiol Via Oestrogen Receptors in the Developing Central Nervous System
Authors: Pozo Devoto V. M. , Giusti S. , Chavez J. C. , Fiszer de Plazas S.
Published: February 2008

The neuroprotective effects of oestrogens have been demonstrated against a variety of insults, including excitotoxicity, oxidative stress and cerebral ischemia under certain conditions. However, the molecular mechanisms underlying oestrogen neuroprotection are still unclear. We aimed to determine whether 17β‐oestradiol (E2) administration post‐hypoxia (p‐hx) was neuroprotective and whether these actions were mediated through oestrogen receptors (ER). For this purpose, 12‐embyonic day‐old chickens were subjected to acute hypoxia [8% (O2), 60 min], followed by different reoxygenation periods. To test the neuroprotective effect of E2 and its mechanism, embryos were injected 30 min after the end of hypoxia with E2 alone or with ICI 182 780, a competitive antagonist of ER. Cytochrome c (cyt c) release, an indicator of mitochondrial apoptotic pathway, was measured by western blot in optic lobe cytosolic extracts. DNA fragmentation by TUNEL fluorescence and caspase‐3 fragmentation by immunofluorescence were detected on optic lobe sections. Acute hypoxia produces a significant increase in cyt c release from mitochondria at 4 h p‐hx, followed by an increase in TUNEL positive cells 2 h later (6 h p‐hx). Administration of E2 (0.5 mg/egg) produced a significant decrease in cytosolic cyt c levels at 4 h p‐hx, in casapse‐3 activation and in TUNEL positive cells at 6 h p‐hx compared to vehicle treated embryos. In the E2‐ICI 182 780 treated embryos, cyt c release, caspase‐3 fragmentation and TUNEL positive cells were similar to the hypoxic embryos, thus suggesting the requirement of an E2–ER interaction for E2 mediated neuroprotective effects. In conclusion, E2 prevents hypoxia‐induced cyt c release and posterior cell death and these effects are mediated by oestrogen receptors.
KiSS‐1 and GPR54 Genes are Co‐Expressed in Rat Gonadotrophs and Differentially Regulated In Vivo by Oestradiol and Gonadotrophin‐Releasing Hormone
Authors: Richard N. , Galmiche G. , Corvaisier S. , Caraty A. , Kottler M.‐L.
Published: February 2008

Kisspeptin, the product derived from KiSS‐1, and its cognate receptor, GPR54, both exert a role in the neuroendocrine control of reproduction by regulating gonadotrophin‐releasing hormone (GnRH) secretion. In the present study, we demonstrate, using dual immunofluorescence with specific antibodies, that the KiSS‐1 and GPR54 genes are both expressed in rat gonadotrophs. All luteinising hormone β‐immunoreactive (LHβ‐ir) cells were stained by the KiSS‐1 antibody but some kisspeptin‐ir cells were not LHβ positive; thus, we cannot exclude the possibility that kisspeptins are expressed in other pituitary cells. All GPR54‐ir are co‐localised with LHβ cells, but only a subset of LHβ cells are stained with the GPR54 antibody. Using the real‐time reverse transcription‐polymerase chain reaction (RT‐PCR), we found that the expression of KiSS‐1 and GPR54 is differentially regulated by steroids. In the female, KiSS‐1 mRNA levels dramatically decreased following ovariectomy (OVX), and this decrease was prevented by administration of 17β‐oestradiol (E2), but not by administration of GnRH antagonist or agonist. Administration of E2 in OVX rats receiving either GnRH antagonist or agonist clearly shows that E2 acts directly on the pituitary to positively control KiSS‐1 expression. In OVX rats, administration of the selective oestrogen receptor (ER)α ligand propylpyrazoletriol, but not the selective ERβ ligand diarylpropionitrile, mimics this effect. By contrast, our study shows that GPR54 expression is positively regulated by GnRH and negatively controlled by chronic exposure to E2. In summary, our data document for the first time that, in the female rat pituitary, KiSS‐1 expression is up‐regulated by oestradiol, similarly to that seen in the anteroventral periventricular nucleus of the hypothalamus. Conversely, GPR54 is up‐regulated by GnRH, which exclusively targets gonadotrophs.