bluuebunny/crossref_metadata_2025 huggingface dataset:
Abl-interactor-1 (Abi1) has a role in cardiovascular and placental development and is a binding partner of the α4 integrin
Authors: Ring Colleen , Ginsberg Mark H. , Haling Jacob , Pendergast Ann Marie
Published: December 2010

Dynamic signals linking the actin cytoskeleton and cell adhesion receptors are essential for morphogenesis during development and normal tissue homeostasis. Abi1 is a central regulator of actin polymerization through interactions with multiple protein complexes. However, the in vivo role of Abi1 remains to be defined. The α4 integrin adhesion receptor is associated with enhanced protrusive activity and regulation of directional cell migration. Among integrin subunits, α4 exhibits unique properties in that it predominantly accumulates at the leading edge of migrating cells; however, the pathways that link the actin-regulatory machinery to α4 at the leading edge have remained elusive. We generated Abi1 KO mice and found that loss of
Abi1
phenocopies KO of
α4
. Mice lacking
Abi1
or
α4
exhibit midgestational lethality with abnormalities in placental and cardiovascular development. Notably, purified Abi1 protein binds directly to the α4 cytoplasmic tail and endogenous Abi1 colocalizes with phosphorylated α4 at the leading edge of spreading cells. Moreover, Abi1-deficient cells expressing α4 have impaired cell spreading, which is rescued by WT Abi1 but not an Abi1 mutant lacking the α4-binding site. These data reveal a direct link between the α4 integrin and actin polymerization and uncover a role for Abi1 in the regulation of morphogenesis in vivo. The Abi1–α4 interaction establishes a mechanistic paradigm for signaling between adhesion events and enhanced actin polymerization at the earliest stages of protrusion.
Feasibility of reconstructed ancestral H5N1 influenza viruses for cross-clade protective vaccine development
Authors: Ducatez Mariette F. , Bahl Justin , Griffin Yolanda , Stigger-Rosser Evelyn , Franks John , Barman Subrata , Vijaykrishna Dhanasekaran , Webb Ashley , Guan Yi , Webster Robert G. , Smith Gavin J. D. , Webby Richard J.
Published: December 2010

Since the reemergence of highly pathogenic H5N1 influenza viruses in humans in 2003, these viruses have spread throughout avian species in Asia, Europe, and Africa. Their sustained circulation has resulted in the evolution of phylogenetically diverse lineages. Viruses from these lineages show considerable antigenic variation, which has confounded vaccine planning efforts. We reconstructed ancestral protein sequences at several nodes of the hemagglutinin (HA) and neuraminidase (NA) gene phylogenies that represent ancestors to diverse H5N1 virus clades. By using the same methods that have been used to generate currently licensed inactivated H5N1 vaccines, we were able to produce a panel of replication competent influenza viruses containing synthesized HA and NA genes representing the reconstructed ancestral proteins. We identified two of these viruses that showed promising in vitro cross-reactivity with clade 1, 2.1, 2.2, 2.3.4, and 4 viruses. To confirm that vaccine antigens derived from these viruses were able to elicit functional antibodies following immunization, we created whole-virus vaccines and compared their protective efficacy versus that of antigens from positive control, naturally occurring, and broadly reactive H5N1 viruses. The ancestral viruses’ vaccines provided robust protection against morbidity and mortality in ferrets challenged with H5N1 strains from clades 1, 2.1, and 2.2 in a manner similar to those based on the control strains. These findings provide proof of principle that viable, computationally derived vaccine seed viruses can be constructed within the context of currently licensed vaccine platforms. Such technologies should be explored to enhance the cross reactivity and availability of H5N1 influenza vaccines.
Intracellular organelles mediate cytoplasmic pulling force for centrosome centration in the
Caenorhabditis elegans
early embryo
Authors: Kimura Kenji , Kimura Akatsuki
Published: December 2010

The centrosome is generally maintained at the center of the cell. In animal cells, centrosome centration is powered by the pulling force of microtubules, which is dependent on cytoplasmic dynein. However, it is unclear how dynein brings the centrosome to the cell center, i.e., which structure inside the cell functions as a substrate to anchor dynein. Here, we provide evidence that a population of dynein, which is located on intracellular organelles and is responsible for organelle transport toward the centrosome, generates the force required for centrosome centration in
Caenorhabditis elegans
embryos. By using the database of full-genome RNAi in
C. elegans
, we identified
dyrb-1
, a dynein light chain subunit, as a potential subunit involved in dynein anchoring for centrosome centration. DYRB-1 is required for organelle movement toward the minus end of the microtubules. The temporal correlation between centrosome centration and the net movement of organelle transport was found to be significant. Centrosome centration was impaired when Rab7 and RILP, which mediate the association between organelles and dynein in mammalian cells, were knocked down. These results indicate that minus end-directed transport of intracellular organelles along the microtubules is required for centrosome centration in
C. elegans
embryos. On the basis of this finding, we propose a model in which the reaction forces of organelle transport generated along microtubules act as a driving force that pulls the centrosomes toward the cell center. This is the first model, to our knowledge, providing a mechanical basis for cytoplasmic pulling force for centrosome centration.
Children with autism are neither systematic nor optimal foragers
Authors: Pellicano Elizabeth , Smith Alastair D. , Cristino Filipe , Hood Bruce M. , Briscoe Josie , Gilchrist Iain D.
Published: December 2010

It is well established that children with autism often show outstanding visual search skills. To date, however, no study has tested whether these skills, usually assessed on a table-top or computer, translate to more true-to-life settings. One prominent account of autism, Baron-Cohen's “systemizing” theory, gives us good reason to suspect that they should. In this study, we tested whether autistic children's exceptional skills at small-scale search extend to a large-scale environment and, in so doing, tested key claims of the systemizing account. Twenty school-age children with autism and 20 age- and ability-matched typical children took part in a large-scale search task in the “foraging room”: a purpose-built laboratory, with numerous possible search locations embedded into the floor. Children were instructed to search an array of 16 (green) locations to find the hidden (red) target as quickly as possible. The distribution of target locations was manipulated so that they appeared on one side of the midline for 80% of trials. Contrary to predictions of the systemizing account, autistic children's search behavior was much less efficient than that of typical children: they showed reduced sensitivity to the statistical properties of the search array, and furthermore, their search patterns were strikingly less optimal and less systematic. The nature of large-scale search behavior in autism cannot therefore be explained by a facility for systemizing. Rather, children with autism showed difficulties exploring and exploiting the large-scale space, which might instead be attributed to constraints (rather than benefits) in their cognitive repertoire.
Cataract-associated mutant E107A of human γD-crystallin shows increased attraction to α-crystallin and enhanced light scattering
Authors: Banerjee Priya R. , Pande Ajay , Patrosz Julita , Thurston George M. , Pande Jayanti
Published: December 2010

Several point mutations in human γD-crystallin (HGD) are now known to be associated with cataract. So far, the in vitro studies of individual mutants of HGD alone have been sufficient in providing plausible molecular mechanisms for the associated cataract in vivo. Nearly all the mutant proteins in solution showed compromised solubility and enhanced light scattering due to altered homologous γ–γ crystallin interactions. In sharp contrast, here we present an intriguing case of a human nuclear cataract-associated mutant of HGD—namely Glu107 to Ala (E107A), which is nearly identical to the wild type in structure, stability, and solubility properties, with one exception: Its pI is higher by nearly one pH unit. This increase dramatically alters its interaction with α-crystallin. There is a striking difference in the liquid–liquid phase separation behavior of E107A–α-crystallin mixtures compared to HGD–α-crystallin mixtures, and the light-scattering intensities are significantly higher for the former. The data show that the two coexisting phases in the E107A–α mixtures differ much more in protein density than those that occur in HGD–α mixtures, as the proportion of α-crystallin approaches that in the lens nucleus. Thus in HGD–α mixtures, the demixing of phases occurs primarily by protein type while in E107A–α mixtures it is increasingly governed by protein density. Analysis of these results suggests that the cataract due to the E107A mutation could result from the instability caused by the altered attractive interactions between dissimilar proteins—i.e., heterologous γ–α crystallin interactions—primarily due to the change in surface electrostatic potential in the mutant protein.
Cardiomyocytes from phorbol myristate acetate-activated mesenchymal stem cells restore electromechanical function in infarcted rat hearts
Authors: Song Heesang , Hwang Hye Jin , Chang Woochul , Song Byeong-Wook , Cha Min-Ji , Kim Il-Kwon , Lim Soyeon , Choi Eun Ju , Ham Onju , Lee Chang Youn , Park Jun-Hee , Lee Se-Yeon , Choi Eunmi , Lee Chungkeun , Lee Myoungho , Lee Moon-Hyoung , Kim Sung-Hou , Jang Yangsoo , Hwang Ki-Chul
Published: December 2010

Despite the safety and feasibility of mesenchymal stem cell (MSC) therapy, an optimal cell type has not yet emerged in terms of electromechanical integration in infarcted myocardium. We found that poor to moderate survival benefits of MSC-implanted rats were caused by incomplete electromechanical integration induced by tissue heterogeneity between myocytes and engrafted MSCs in the infarcted myocardium. Here, we report the development of cardiogenic cells from rat MSCs activated by phorbol myristate acetate, a PKC activator, that exhibited high expressions of cardiac-specific markers and Ca
2+
homeostasis-related proteins and showed adrenergic receptor signaling by norepinephrine. Histological analysis showed high connexin 43 coupling, few inflammatory cells, and low fibrotic markers in myocardium implanted with these phorbol myristate acetate-activated MSCs. Infarct hearts implanted with these cells exhibited restoration of conduction velocity through decreased tissue heterogeneity and improved myocardial contractility. These findings have major implications for the development of better cell types for electromechanical integration of cell-based treatment for infarcted myocardium.
Mechanism of inactivation of influenza viruses by immobilized hydrophobic polycations
Authors: Hsu Bryan B. , Yinn Wong Sze , Hammond Paula T. , Chen Jianzhu , Klibanov Alexander M.
Published: December 2010

N,N-Dodecyl,methyl-polyethylenimine coatings applied to solid surfaces have been shown by us to disinfect aqueous solutions of influenza viruses. Herein we elucidate the mechanism of this phenomenon. Infectivity-, protein-, RNA-, and scanning electron microscopy-based experiments reveal that, upon contact with the hydrophobic polycationic coating, influenza viruses (including pathogenic human and avian, both wild-type and drug-resistant, strains) irreversibly adhere to it, followed by structural damage and inactivation; subsequently, viral RNA is released into solution, while proteins remain adsorbed.
HURP permits MTOC sorting for robust meiotic spindle bipolarity, similar to extra centrosome clustering in cancer cells
Authors: Breuer Manuel , Kolano Agnieszka , Kwon Mijung , Li Chao-Chin , Tsai Ting-Fen , Pellman David , Brunet Stéphane , Verlhac Marie-Hélène
Published: December 2010

In contrast to somatic cells, formation of acentriolar meiotic spindles relies on the organization of microtubules (MTs) and MT-organizing centers (MTOCs) into a stable bipolar structure. The underlying mechanisms are still unknown. We show that this process is impaired in hepatoma up-regulated protein (Hurp) knockout mice, which are viable but female sterile, showing defective oocyte divisions. HURP accumulates on interpolar MTs in the vicinity of chromosomes via Kinesin-5 activity. By promoting MT stability in the spindle central domain, HURP allows efficient MTOC sorting into distinct poles, providing bipolarity establishment and maintenance. Our results support a new model for meiotic spindle assembly in which HURP ensures assembly of a central MT array, which serves as a scaffold for the genesis of a robust bipolar structure supporting efficient chromosome congression. Furthermore, HURP is also required for the clustering of extra centrosomes before division, arguing for a shared molecular requirement of MTOC sorting in mammalian meiosis and cancer cell division.
A computational model predicts Xenopus meiotic spindle organization
Authors: Loughlin Rose , Heald Rebecca , Nédélec François
Published: December 2010

The metaphase spindle is a dynamic bipolar structure crucial for proper chromosome segregation, but how microtubules (MTs) are organized within the bipolar architecture remains controversial. To explore MT organization along the pole-to-pole axis, we simulated meiotic spindle assembly in two dimensions using dynamic MTs, a MT cross-linking force, and a kinesin-5–like motor. The bipolar structures that form consist of antiparallel fluxing MTs, but spindle pole formation requires the addition of a NuMA-like minus-end cross-linker and directed transport of MT depolymerization activity toward minus ends. Dynamic instability and minus-end depolymerization generate realistic MT lifetimes and a truncated exponential MT length distribution. Keeping the number of MTs in the simulation constant, we explored the influence of two different MT nucleation pathways on spindle organization. When nucleation occurs throughout the spindle, the simulation quantitatively reproduces features of meiotic spindles assembled in Xenopus egg extracts.
Thymus-specific serine protease contributes to the diversification of the functional endogenous CD4 T cell receptor repertoire
Authors: Viret Christophe , Lamare Camille , Guiraud Martine , Fazilleau Nicolas , Bour Agathe , Malissen Bernard , Carrier Alice , Guerder Sylvie
Published: December 2010

Thymus-specific serine protease (TSSP) is a novel protease that may contribute to the generation of the peptide repertoire presented by MHC class II molecules in the thymus. Although TSSP deficiency has no quantitative impact on the development of CD4 T cells expressing a polyclonal T cell receptor (TCR) repertoire, the development of CD4 T cells expressing the OTII and Marilyn transgenic TCRs is impaired in TSSP-deficient mice. In this study, we assess the role of TSSP in shaping the functional endogenous polyclonal CD4 T cell repertoire by analyzing the response of TSSP-deficient mice to several protein antigens (Ags). Although TSSP-deficient mice responded normally to most of the Ags tested, they responded poorly to hen egg lysozyme (HEL). The impaired CD4 T cell response of TSSP-deficient mice to HEL correlated with significant alteration of the dominant TCR-β chain repertoire expressed by HEL-specific CD4 T cells, suggesting that TSSP is necessary for the intrathymic development of cells expressing these TCRs. Thus, TSSP contributes to the diversification of the functional endogenous CD4 T cell TCR repertoire in the thymus.
Fast tomographic reconstruction on multicore computers
Authors: Agulleiro J. I. , Fernandez J. J.
Published: December 2010

Summary: Tomo3D implements a multithreaded vectorized approach to tomographic reconstruction that takes full advantage of the computer power in modern multicore computers. Full resolution tomograms are generated at high speed on standard computers with no special system requirements. Tomo3D has the most common reconstruction methods implemented, namely weighted Back-projection (WBP) and simultaneous iterative reconstruction technique (SIRT). It proves to be competitive with current graphic processor unit solutions in terms of processing time, in the order of a few seconds with WBP or minutes with SIRT. The program is compatible with standard packages, which easily allows integration in the electron tomography workflow.

Availability:  http://www.cnb.csic.es/%7ejjfernandez/tomo3d

Contact:  JJ.Fernandez@cnb.csic.es

Supplementary information:  Supplementary data are available at Bioinformatics online.
Selective ploidy ablation, a high-throughput plasmid transfer protocol, identifies new genes affecting topoisomerase I–induced DNA damage
Authors: Reid Robert J.D. , González-Barrera Sergio , Sunjevaric Ivana , Alvaro David , Ciccone Samantha , Wagner Marisa , Rothstein Rodney
Published: December 2010

We have streamlined the process of transferring plasmids into any yeast strain library by developing a novel mating-based, high-throughput method called selective ploidy ablation (SPA). SPA uses a universal plasmid donor strain that contains conditional centromeres on every chromosome. The plasmid-bearing donor is mated to a recipient, followed by removal of all donor-strain chromosomes, producing a haploid strain containing the transferred plasmid. As proof of principle, we used SPA to transfer plasmids containing wild-type and mutant alleles of DNA topoisomerase I (TOP1) into the haploid yeast gene-disruption library. Overexpression of Top1 identified only one sensitive mutation,rpa34, while overexpression oftop1-T722Aallele, a camptothecin mimetic, identified 190 sensitive gene-disruption strains along withrpa34. In addition to known camptothecin-sensitive strains, this set contained mutations in genes involved in the Rpd3 histone deacetylase complex, the kinetochore, and vesicle trafficking. We further show that mutations in several ESCRT vesicle trafficking components increase Top1 levels, which is dependent on SUMO modification. These findings demonstrate the utility of the SPA technique to introduce plasmids into the haploid gene-disruption library to discover new interacting pathways.
RNA sequencing reveals the role of splicing polymorphisms in regulating human gene expression
Authors: Lalonde Emilie , Ha Kevin C.H. , Wang Zibo , Bemmo Amandine , Kleinman Claudia L. , Kwan Tony , Pastinen Tomi , Majewski Jacek
Published: December 2010

Expression levels of many human genes are under the genetic control of expression quantitative trait loci (eQTLs). Despite technological advances, the precise molecular mechanisms underlying most eQTLs remain elusive. Here, we use deep mRNA sequencing of two CEU individuals to investigate those mechanisms, with particular focus on the role of splicing control loci (sQTLs). We identify a large number of genes that are differentially spliced between the two samples and associate many of those differences with nearby single nucleotide polymorphisms (SNPs). Subsequently, we investigate the potential effect of splicing SNPs on eQTL control in general. We find a significant enrichment of alternative splicing (AS) events within a set of highly confident eQTL targets discovered in previous studies, suggesting a role of AS in regulating overall gene expression levels. Next, we demonstrate high correlation between the levels of mature (exonic) and unprocessed (intronic) RNA, implying that ∼75% of eQTL target variance can be explained by control at the level of transcription, but that the remaining 25% may be regulated co- or post-transcriptionally. We focus on eQTL targets with discordant mRNA and pre-mRNA expression patterns and use four examples: USMG5, MMAB, MRPL43, and OAS1, to dissect the exact downstream effects of the associated genetic variants.
Bubble-chip analysis of human origin distributions demonstrates on a genomic scale significant clustering into zones and significant association with transcription
Authors: Mesner Larry D. , Valsakumar Veena , Karnani Neerja , Dutta Anindya , Hamlin Joyce L. , Bekiranov Stefan
Published: December 2010

We have used a novel bubble-trapping procedure to construct nearly pure and comprehensive human origin libraries from early S- and log-phase HeLa cells, and from log-phase GM06990, a karyotypically normal lymphoblastoid cell line. When hybridized to ENCODE tiling arrays, these libraries illuminated 15.3%, 16.4%, and 21.8% of the genome in the ENCODE regions, respectively. Approximately half of the origin fragments cluster into zones, and their signals are generally higher than those of isolated fragments. Interestingly, initiation events are distributed about equally between genic and intergenic template sequences. While only 13.2% and 14.0% of genes within the ENCODE regions are actually transcribed in HeLa and GM06990 cells, 54.5% and 25.6% of zonal origin fragments overlap transcribed genes, most with activating chromatin marks in their promoters. Our data suggest that cell synchronization activates a significant number of inchoate origins. In addition, HeLa and GM06990 cells activate remarkably different origin populations. Finally, there is only moderate concordance between the log-phase HeLa bubble map and published maps of small nascent strands for this cell line.
Unique Thylakoid Membrane Architecture of a Unicellular N2-Fixing Cyanobacterium Revealed by Electron Tomography
Authors: Liberton Michelle , Austin Jotham R. , Berg R. Howard , Pakrasi Himadri B.
Published: December 2010

Cyanobacteria, descendants of the endosymbiont that gave rise to modern-day chloroplasts, are vital contributors to global biological energy conversion processes. A thorough understanding of the physiology of cyanobacteria requires detailed knowledge of these organisms at the level of cellular architecture and organization. In these prokaryotes, the large membrane protein complexes of the photosynthetic and respiratory electron transport chains function in the intracellular thylakoid membranes. Like plants, the architecture of the thylakoid membranes in cyanobacteria has direct impact on cellular bioenergetics, protein transport, and molecular trafficking. However, whole-cell thylakoid organization in cyanobacteria is not well understood. Here we present, by using electron tomography, an in-depth analysis of the architecture of the thylakoid membranes in a unicellular cyanobacterium, Cyanothece sp. ATCC 51142. Based on the results of three-dimensional tomographic reconstructions of near-entire cells, we determined that the thylakoids in Cyanothece 51142 form a dense and complex network that extends throughout the entire cell. This thylakoid membrane network is formed from the branching and splitting of membranes and encloses a single lumenal space. The entire thylakoid network spirals as a peripheral ring of membranes around the cell, an organization that has not previously been described in a cyanobacterium. Within the thylakoid membrane network are areas of quasi-helical arrangement with similarities to the thylakoid membrane system in chloroplasts. This cyanobacterial thylakoid arrangement is an efficient means of packing a large volume of membranes in the cell while optimizing intracellular transport and trafficking.
Loss-of-Function and Gain-of-Function Mutations in FAB1A/B Impair Endomembrane Homeostasis, Conferring Pleiotropic Developmental Abnormalities in Arabidopsis
Authors: Hirano Tomoko , Matsuzawa Tomohiko , Takegawa Kaoru , Sato Masa H.
Published: December 2010

In eukaryotic cells, PtdIns 3,5-kinase, Fab1/PIKfyve produces PtdIns (3,5) P2 from PtdIns 3-P, and functions in vacuole/lysosome homeostasis. Herein, we show that expression of Arabidopsis (Arabidopsis thaliana) FAB1A/B in fission yeast (Schizosaccharomyces pombe) fab1 knockout cells fully complements the vacuole morphology phenotype. Subcellular localizations of FAB1A and FAB1B fused with green fluorescent protein revealed that FAB1A/B-green fluorescent proteins localize to the endosomes in root epidermal cells of Arabidopsis. Furthermore, reduction in the expression levels of FAB1A/B by RNA interference impairs vacuolar acidification and endocytosis. These results indicate that Arabidopsis FAB1A/B functions as PtdIns 3,5-kinase in plants and in fission yeast. Conditional knockdown mutant shows various phenotypes including root growth inhibition, hyposensitivity to exogenous auxin, and disturbance of root gravitropism. These phenotypes are observed also in the overproducing mutants of FAB1A and FAB1B. The overproducing mutants reveal additional morphological phenotypes including dwarfism, male-gametophyte sterility, and abnormal floral organs. Taken together, this evidence indicates that imbalanced expression of FAB1A/B impairs endomembrane homeostasis including endocytosis, vacuole formation, and vacuolar acidification, which causes pleiotropic developmental phenotypes mostly related to the auxin signaling in Arabidopsis.
Three Homologous Genes Encodingsn-Glycerol-3-Phosphate Acyltransferase 4 Exhibit Different Expression Patterns and Functional Divergence inBrassica napus
Authors: Chen Xue , Truksa Martin , Snyder Crystal L. , El-Mezawy Aliaa , Shah Saleh , Weselake Randall J.
Published: December 2010

Brassica  napus is an allotetraploid (AACC) formed from the fusion of two diploid progenitors, Brassica rapa (AA) and Brassica oleracea (CC). Polyploidy and genome-wide rearrangement during the evolution process have resulted in genes that are present as multiple homologs in the B. napus genome. In this study, three B. napus homologous genes encoding endoplasmic reticulum-bound sn-glycerol-3-phosphate acyltransferase 4 (GPAT4) were identified and characterized. Although the three GPAT4 homologs share a high sequence similarity, they exhibit different expression patterns and altered epigenetic features. Heterologous expression in yeast further revealed that the three BnGPAT4 homologs encoded functional GPAT enzymes but with different levels of polypeptide accumulation. Complementation of the Arabidopsis (Arabidopsis thaliana) gpat4 gpat8 double mutant line with individual BnGPAT4 homologs suggested their physiological roles in cuticle formation. Analysis of gpat4 RNA interference lines of B. napus revealed that the BnGPAT4 deficiency resulted in reduced cutin content and altered stomatal structures in leaves. Our results revealed that the BnGPAT4 homologs have evolved into functionally divergent forms and play important roles in cutin synthesis and stomatal development.
Progesterone enhances adrenergic control of skin blood flow in women with high but not low orthostatic tolerance
Authors: Wenner Megan M. , Taylor Hugh S. , Stachenfeld Nina S.
Published: December 2010

Non‐technical summary Women experience orthostatic intolerance (the inability to maintain blood pressure during postural changes) more frequently than men. This difference between men and women may in part be related to how oestradiol and progesterone influence dilatation and constriction of blood vessels. We show that progesterone enhances vasoconstriction in women who have a higher tolerance to orthostatic stress, but not in women with low tolerance. The increase in vasoconstriction with progesterone administration in women with high tolerance appears to be mediated by prostaglandins (hormone‐like substances that assist in maintaining bodily functions). These results show that progesterone alters blood vessel constriction and can help us understand blood pressure regulation in women.
Regulation of visceral sympathetic tone by A5 noradrenergic neurons in rodents
Authors: Kanbar Roy , Depuy Seth D. , West Gavin H. , Stornetta Ruth L. , Guyenet Patrice G.
Published: December 2010

Non‐technical summaryPatients suffering from obstructive sleep apnoea (OSA) experience repeated decreases in blood oxygen (hypoxia) and increases in CO2(hypercapnia) causing sleep disruption, cardiac over‐stimulation, intense vasoconstriction and, eventually, day‐time hypertension. Hypoxia and hypercapnia initiate these responses by activating the carotid bodies whereas hypercapnia also works in the central nervous system. In this study in anaesthetized rats we show that a group of noradrenergic neurons located in the lower brainstem (A5 neurons) are vigorously activated by carotid body stimulation and mildly affected by CO2. We also show that selective activation of the A5 neurons increases sympathetic tone to the viscera and we suggest that these catecholaminergic neurons contribute to the cardiovascular stimulation caused by acute hypoxia. The importance of the A5 neurons to acute hypoxic responses in the conscious state remains to be assessed and their contribution to the day‐time hypertension associated with OSA is also a matter for future research.
T‐type calcium channels and vascular function: the new kid on the block?
Authors: Kuo Ivana Y.‐T. , Wölfle Stephanie E. , Hill Caryl E.
Published: December 2010

Abstract While L‐type voltage‐dependent calcium channels have long been considered the predominant source of calcium for myogenic constriction, recent studies of both cerebral and systemic circulations have provided evidence for the prominent expression of other members of the voltage‐dependent calcium channel family, in particular the low voltage activated T‐type channels. Although physiological studies have not supported the involvement of a classical low voltage activated, T‐type channel in vascular function, evidence is accumulating that points to the involvement of a non‐L‐type, high voltage activated channel with sensitivity to T‐type channel antagonists. We propose that this may arise due to expression of a T‐type channel splice variant with unique biophysical characteristics resulting in a more depolarised profile. Expression of these channels in smooth muscle cells would broaden the voltage range over which sustained calcium influx occurs, while expression of T‐type channels in endothelial cells could provide a feedback mechanism to prevent excessive vasoconstriction. Perturbation of this balance during pathophysiological conditions by upregulation of channel expression and endothelial dysfunction could contribute to vasospastic conditions and therapy‐refractory hypertension.
Retinoic acid stimulation of VEGF secretion from human endometrial stromal cells is mediated by production of reactive oxygen species
Authors: Wu Juanjuan , Hansen Jason M. , Hao Lijuan , Taylor Robert N. , Sidell Neil
Published: December 2010

Non‐technical summary Vascular endothelial growth factor (VEGF) is an angiogenic factor that plays a primary role in blood vessel development in uterine endometrial tissue during embryo implantation and early growth. Previously, we determined that retinoic acid (RA) can act as a co‐factor to rapidly induce VEGF secretion from human endometrial stromal cells. We show here that stimulation of VEGF by RA is directly mediated by increased production of reactive oxygen species (ROS) in these cells. These findings predict a ROS‐mediated mechanism for RA regulation of localized VEGF secretion in the human endometrium that may be necessary for the successful establishment of pregnancy. The results obtained may provide new targets for therapeutic intervention.
Etomidate and propofol inhibit the neurotransmitter release machinery at different sites
Authors: Herring Bruce E. , McMillan Kyle , Pike Carolyn M. , Marks Jeremy , Fox Aaron P. , Xie Zheng
Published: December 2010

Non‐technical summary  Alterations in synaptic efficacy are thought to underlie changes in learning and behaviour and are vital to normal neuronal function. Using a variety of different cells and techniques we investigate whether anaesthetics can modify neurotransmitter release as part of their mechanism of action. Our data suggest that inhibition of neurotransmitter release may be a critical mechanism for the actions of anaesthetics like etomidate and propofol. In the future this information may be used to design new generations of clinically useful anaesthetics.
A functional role for the ‘fibroblast‐like cells’ in gastrointestinal smooth muscles
Authors: Kurahashi Masaaki , Zheng Haifeng , Dwyer Laura , Ward Sean M. , Don Koh Sang , Sanders Kenton M.
Published: December 2010

Non‐technical summary

Smooth muscles, as in the gastrointestinal tract, are composed of several types of cells. Gastrointestinal muscles contain smooth muscle cells, enteric neurons, glial cells, immune cells, and various classes of interstitial cells. One type of interstitial cell, referred to as ‘fibroblast‐like cells’ by morphologists, are common, but their function is unknown. These cells are found near the terminals of enteric motor neurons, suggesting they could have a role in generating neural responses that help control gastrointestinal movements. We used a novel mouse with bright green fluorescent protein expressed specifically in the fibroblast‐like cells to help us identify these cells in the mixture of cells obtained when whole muscles are dispersed with enzymes. We isolated these cells and found they respond to a major class of inhibitory neurotransmitters – purines. We characterized these responses, and our results provide a new hypothesis about the role of fibroblast‐like cells in smooth muscle tissues.
Emerging concepts for the role of TRP channels in the cardiovascular system
Authors: Vennekens Rudi
Published: December 2010

Abstract  The transient receptor potential (TRP) family of ion channels is a large family of cation selective ion channels, which are expressed and functional in a variety of tissues. In this review we focus on the most recent results detailing the role of TRP channels in the cardiovascular system. The presented results underscore the role of TRP channels in cardiomyocytes, smooth cells and endothelium, and in disease states such as hypertension, cardiac conduction block and cardiac hypertrophy.
Laser-Assisted Machining of a Fiber Reinforced Metal Matrix Composite
Authors: Dandekar Chinmaya R. , Shin Yung C.
Published: December 2010

Metal matrix composites, due to their excellent properties of high specific strength, fracture resistance, and corrosion resistance, are highly sought after over their nonferrous alloys, but these materials also present difficulty in machining. Excessive tool wear and high tooling costs of diamond tools make the cost associated with machining of these composites very high. This paper is concerned with the machining of high volume fraction long-fiber metal matrix composites (MMCs), which has seldom been studied. The composite material considered for this study is an Al–2% Cu aluminum matrix composite reinforced with 62% by volume fraction alumina fibers (Al–2% Cu/Al2O3). Laser-assisted machining (LAM) is utilized to improve the tool life and the material removal rate while minimizing the subsurface damage. The effectiveness of the laser-assisted machining process is studied by measuring the cutting forces, specific cutting energy, surface roughness, subsurface damage, and tool wear under various material removal temperatures. A multiphase finite element model is developed in ABAQUS/STANDARD to assist in the selection of cutting parameters such as tool rake angle, cutting speed, and material removal temperature. The multiphase model is also successful in predicting the damage depth on machining. The optimum material removal temperature is established as 300°C at a cutting speed of 30 m/min. LAM provides a 65% reduction in the surface roughness, specific cutting energy, tool wear rate, and minimum subsurface damage over conventional machining using the same cutting conditions.
Three-Dimensional Numerical Simulation and Experimental Study of Sheet Metal Bending by Laser Peen Forming
Authors: Hu Yongxiang , Han Yefei , Yao Zhenqiang , Hu Jun
Published: December 2010

Laser peen forming (LPF) is a purely mechanical forming method achieved through the use of laser energy to form complex shapes or to modify curvatures. It is flexible and independent of tool inaccuracies that result from wear and deflection. Its nonthermal process makes it possible to form without material degradation or even improve them by inducing compressive stress over the target surface. In the present study, a fully three-dimensional numerical model is developed to simulate the forming process of laser peen forming. The simulation procedure is composed of several steps mainly including the shock pressure prediction, the modal analysis, and the forming process calculation. System critical damping is introduced to prevent unnecessary long post-shock residual oscillations and to greatly decrease the solution time for simulation. The bending profiles and angles with different thicknesses are experimentally measured at different scanning lines and scanning velocities to understand the process and validate the numerical model. The calculated bending profiles and angles agree well with the trend of the measured results. But it is found that simulations with the Johnson–Cook model are more consistent, matching the experimental results for the thick sheet metal with a convex bending, while the elastic-perfectly-plastic model produces a better agreement even though with underestimated values for the thinner sheet metal with a concave bending. The reason for this phenomenon is discussed, combining the effects of strain rate and feature size. Both the simulation and the experiments show that a continuous decrease in bending angle from concave to convex is observed with increasing specimen thickness in general. Large bending distortion is easier to induce by generating a concave curvature with LPF, and the angle of bending distortion depends on the number of laser shocks.
Effects of Temperature on Laser Shock Induced Plastic Deformation: The Case of Copper
Authors: Ye Chang , Cheng Gary J.
Published: December 2010

Laser shock induced plastic deformation has been used widely, such as laser shock peening (LSP), laser dynamic forming (LDF), and laser peen forming. These processes have been extensively studied both numerically and experimentally at room temperature. Recently, it is found that at elevated temperature, laser shock induced plastic deformation can generate better formability in LDF and enhanced mechanical properties in LSP. For example, warm laser shock peening leads to improved residual stress stability and better fatigue performance in aluminum alloys. There is a need to investigate the effects of elevated temperature on deformation behavior of metallic materials during shock induced high strain rate deformation. In this study, LSP of copper are selected to systematically study the effects of elevated temperature in shock induced high strain rate deformation. Finite element modeling (FEM) is used to predict the deformation behavior. The FEM simulation results of surface profile and residual stress distribution after LSP are validated by experimental results. The validated FEM simulation is used to study the effects of temperature on the plastic deformation behaviors during LSP, such as plastic affected zone, stress/strain distribution, and energy absorption.
Diffusion Driven Desalination for Simultaneous Fresh Water Production and Desulfurization
Authors: Khan Jameel R. , Klausner James F. , Ziegler Donald P. , Garimella Srinivas S.
Published: December 2010

The diffusion driven desalination (DDD) process has been previously introduced as a process for distilling water using low-grade waste heat. Here, a configuration of the DDD process is introduced for simultaneously distilling water and scrubbing sulfur dioxide (SO2) out of heated air streams, which is also known as flue gas desulfurization (FGD). This novel DDD/FGD process utilizes the low-grade waste heat carried in industrial discharge air streams. There are many applications, where the industrial air discharge also contains SO2, and in order to utilize the waste heat for the DDD process, the SO2 must be scrubbed out of the air stream. The two major components of the DDD process are the diffusion tower and the direct contact condenser. In the present work, a thermal fluid transport model for the DDD/FGD process, that includes SO2 scrubbing, is developed. It is an extension of the heat and mass transport model previously reported for the DDD process. An existing laboratory scale DDD facility was modified and tested with SO2 in the air stream and with seawater as the feed water to the diffusion tower. The experimental investigation has been completed to evaluate the fresh water production and SO2 scrubbing potential for the DDD/FGD process. The experimental results compare favorably with the model predictions. Chemical analysis on the condenser water demonstrates the capability of the DDD/FGD process to produce high quality fresh water using seawater as the input feed water to the process.
Radiological Monitoring Systems for Waste Characterisation in the Environment of Our Decommissioning Solutions
Authors: Sokcic-Kostic Marina , Schultheis Roland
Published: December 2010

Decommissioning and dismantling of nuclear sites is an increasing business in Europe and worldwide. New methods and instruments are demanded to perform it effectively and economically. NUKEM Technologies has accepted this challenge and has shown that there is a specific solution for each task. Nukem monitoring systems include Bridge Monitors for incoming radwaste, Sorting Monitors to separate low, intermediate and high level waste, Drum/Container Monitors mainly for outgoing waste, Monitors for Room Clearance Measurements and High Throughput Free Release Measurement Systems. The last monitor was designed for a 100% measurement of soil or building material with up to 50.000 kg waste throughput per hour.
Environmental Remediation and Using a New Sorting and Free Release System for Contaminated Soil at NPP A1 Site, Slovakia
Authors: Slavik Ondrej , Baca Miroslav , Slaninka Alojz , Janecka Stanislav , Sirota Ja´n
Published: December 2010

Environmental remediation at NPP A1 site is even presently a continual process of removing the contamination from the ground or auxuliary objects within the NPP A-1 site with accidentally shut down reactor. This paper mainly deal with monitoring, sorting out and disposal of large volumes of removed contaminated soil stored temporarily until now at the site which is necessary for enhancement of environmental radiation situation at the site. It was also one of the topic of the Decommissioning Project of NPP A1, Slovakia, - Phase No I, lasted from 1999 to 2008. Within the project, attention was paid to development of technical tools for handling with and monitoring of large volume of contaminated soil, as well. Besides short description of contaminated lands at the site, sources of their contamination and to date known inventory, details of a pilot contaminated soil sorting facility developed and tested recently within the Decommissioning project will be described and discussed in the papper. The paper topics include description of and uncertainty analysis results for the pilot soil sorting system based on the Canberra-Packard pilot conveyer belt monitor with a pair of 1.5 inch LaBr scintilation detectors and integrated electronic belt scale. In addition experiences learned during the metrological testing and operational trial will be summarised. MDA for Cs-137 of this system is 140 Bq/kg for 30 kg and 50 Bq/kg for 300 kg parts of soil at 500 Bq/kg of 40K and 0.15 mikroGy/h.
Benefits of Low Resolution Gamma Spectroscopy (LRGS) in Assessment and Remediation of Alpha Contamination
Authors: McBarron Martha , Cassidy Jim , Hutton Louise
Published: December 2010

The legacy of alpha contamination in an exterior disused storage area at the Low Level Waste Repository (LLWR) presented difficult challenges with regard to assessment and remediation. The area was heavily overgrown, with degraded remnant surfaces and debris from past demolition activities. The use of conventional field instruments and/or an extensive intrusive sampling programme were precluded as being impractical, the latter prohibitively costly and not expeditious. This paper describes the identification of a cost-effective alternative for the initial site assessment and the role of LRGS in the subsequent remediation work. It includes: 1 identification and selection of a field instrumentation/system for investigating the site. 2 details of the TERRIER™ system, incorporating the SAM935 Low Resolution Gamma Spectrometer (LRGS) with the capability of real time identification of nuclides. 3 use of the TERRIER™ for a non-intrusive survey of the site, with rapid transformation of field data into informative plots useful for remediation planning. 4 use of the TERRIER™ during remediation work, including assay of arisings. 5 benefits and limitations of using LRGS to support remediation of alpha contamination. 6 application of the instrumentation/system to other radiological investigations.
Disposal of Spent Fuel From German Nuclear Power Plants
Authors: Graf Reinhold , Filbert Wolfgang , Brammer Klaus-Ju¨rgen , Bollingerfehr Wilhelm
Published: December 2010

The “direct disposal of spent fuel” as a part of the current German reference concept was developed as an alternative to spent fuel reprocessing and vitrified HLW disposal. The technical facilities necessary for the implementation of this part of the reference concept, the so called POLLUX® concept, i.e. interim storage buildings for casks containing spent fuel, a pilot conditioning facility, and a special cask “POLLUX” for final disposal have been built. With view to a geological salt formation all handling procedures for the direct disposal of spent fuel were tested aboveground in full-scale test facilities. To optimise the reference concept, all operational steps have been reviewed for possible improvements. The two additional concepts for the direct disposal of SF are the BSK 3 concept and the DIREGT concept. Both concepts rely on borehole emplacement technology, vertical boreholes for the BSK 3 concept und horizontal boreholes for the DIREGT concept. Supported by the EU and the German Federal Ministry of Economics and Technology (BMWi), DBE TECHNOLOGY built an aboveground full-scale test facility to simulate all relevant handling procedures for the BSK 3 disposal concept. GNS (Company for Nuclear Service), representing the German utilities, provided the main components and its know-how concerning cask design and manufacturing. The test program was concluded recently after more than 1.000 emplacement operations had been performed successfully. The BSK 3 emplacement system in total comprises an emplacement device, a borehole lock, a transport cart, a transfer cask which will shuttle between the aboveground conditioning facility and the underground repository, and the BSK 3 canister itself, designed to contain the fuel rods of three PWR-fuel assemblies with a total of about 1.6 tHM. The BSK 3 concept simplifies the operation of the repository because the handling procedures and techniques can also be applied for the disposal of reprocessing residues. In addition to this, the feasibility of the direct disposal of transport and storage casks, the so-called “DIREGT concept”, is being investigated. The implementation of this concept would avoid the necessity to separate fuel rods from structural parts and to procure custom-made final disposal casks. All investigations and studies performed so far support the feasibility of direct disposal of spent fuel in multipurpose casks as today used for transport and storage. Both additional concepts, BSK 3 and DIREGT, are expected to simplify disposal processes and to reduce operational risk without any compromise in long-term radiological safety aspects.