bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of the Abbott
m
2000 RealTi
m
e Human Immunodeficiency Virus Type 1 (HIV-1) Assay for HIV Load Monitoring in South Africa Compared to the Roche Cobas AmpliPrep-Cobas Amplicor, Roche Cobas AmpliPrep-Cobas TaqMan HIV-1, and BioMerieux NucliSENS EasyQ HIV-1 Assays
Authors: Scott Lesley E. , Noble Lara D. , Moloi Jackie , Erasmus Linda , Venter Willem D. F. , Stevens Wendy
Published: May 2009

The implementation of antiretroviral therapy demands the need for increased access to viral load (VL) monitoring. Newer real-time VL testing technologies are faster and have larger dynamic ranges and fully automated extraction to benefit higher throughputs in resource-poor environments. The Abbott RealTi
m
e human immunodeficiency virus type 1 (HIV-1) assay was evaluated as a new option for testing for HIV-1 subtype C in South Africa, and its performance was compared to the performance of existing assays (the Cobas AmpliPrep-Cobas TaqMan HIV-1, version 1, assay; the AmpliPrep-Cobas Monitor standard HIV-1 assay; and the NucliSENS EasyQ-EasyMag HIV-1 assay) in a high-throughput laboratory. The total precision of the RealTi
m
e HIV-1 assay was acceptable over all viral load ranges. This assay compared most favorably with the Cobas AmpliPrep-Cobas TaqMan HIV-1 assay (
R
2
= 0.904), with a low standard deviation of difference being detected (0.323 copies/ml). The bias against comparator assays ranged from −0.001 copies/ml to −0.228 copies/ml. Variability in the reporting of VLs for a 20-member subtype panel compared to the variability of other assays was noted with subtypes G and CRF02-AG. The RealTi
m
e HIV-1 assay can test 93 samples per day with minimal manual preparation, less staff, and the minimization of contamination through automation. This assay is suitable for HIV-1 subtype C VL quantification in South Africa.
Immediate Appearance of Plasmid-Mediated Resistance to Multiple Antibiotics upon Antibiotic Selection: an Argument for Systematic Resistance Epidemiology
Authors: van Hal Sebastiaan J. , Wiklendt Agnieszka , Espedido Björn , Ginn Andrew , Iredell Jonathan R.
Published: May 2009

We describe a conjugative plasmid appearing in a bacteremic clone of
Escherichia coli
immediately upon exposure to the antibiotics for which it encoded resistance. Effective antibiotic choice was made possible by prior screening for this plasmid. Surveillance for transmissible resistance plasmids may be clinically important.
Cytokine Imbalance after Measles Virus Infection Has No Correlation with Immune Suppression
Authors: Carsillo Mary , Klapproth Kay , Niewiesk Stefan
Published: May 2009

Measles virus infection leads to immune suppression. A potential mechanism is the reduction of interleukin 12 (IL-12) secretion during acute measles, resulting in a TH2 response. Studies in humans have reported conflicting results, detecting either a TH2 or a TH1 response. We have investigated the correlation between a TH2 response and immune suppression in specific-pathogen-free inbred cotton rats which were infected with measles vaccine and wild-type viruses. After infection of bone marrow-derived macrophages with wild-type virus, IL-12 secretion was reduced in contrast to the level for vaccine virus infection. In bronchoalveolar lavage cells, IL-12 secretion was suppressed after infection with both wild-type and vaccine virus on days 2, 4, and 6 and was detectable on days 8 and 10. After stimulation of mediastinal lymph node and spleen cells with UV-inactivated measles virus at various time points after infection, gamma interferon but no IL-4 was found. After stimulation with phorbol myristate acetate-ionomycin, high gamma interferon and low IL-4 levels were detected. To investigate whether the secretion of IL-4 contributes to immune suppression, a recombinant vaccine virus was created which secretes cotton rat IL-4. After infection with this recombinant virus, IL-4 secretion was enhanced. However, neither inhibition of concanavalin A-stimulated spleen cells nor keyhole limpet hemocyanin-specific proliferation of spleen cells was altered after infection with the recombinant virus in comparison to the levels with the parental virus. Our data indicate that measles virus infection leads to a decrease in IL-12 secretion and an increase in IL-4 secretion, but this does not seem to correlate with immune suppression.
The RING Domain and the L79 Residue of Z Protein Are Involved in both the Rescue of Nucleocapsids and the Incorporation of Glycoproteins into Infectious Chimeric Arenavirus-Like Particles
Authors: Casabona Juan Cruz , Levingston Macleod Jesica M. , Loureiro Maria Eugenia , Gomez Guillermo A. , Lopez Nora
Published: May 2009

Arenaviruses, such as Tacaribe virus (TacV) and its closely related pathogenic Junin virus (JunV), are enveloped viruses with a bipartite negative-sense RNA genome that encodes the nucleocapsid protein (N), the precursor of the envelope glycoprotein complex (GP), the polymerase (L), and a RING finger protein (Z), which is the driving force of arenavirus budding. We have established a plasmid-based system which allowed the successful packaging of TacV-like nucleocapsids along with Z and GP of JunV into infectious virus-like particles (VLPs). By coexpressing different combinations of the system components, followed by biochemical analysis of the VLPs, the requirements for the assembly of both N and GP into particles were defined. We found that coexpression of N with Z protein in the absence of minigenome and other viral proteins was sufficient to recruit N within lipid-enveloped Z-containing VLPs. In addition, whereas GP was not required for the incorporation of N, coexpression of N substantially enhanced the ratio of GP to Z into VLPs. Disruption of the RING structure or mutation of residue L79 to alanine within Z protein, although it had no effect on Z self-budding, severely impaired VLP infectivity. These mutations drastically altered intracellular Z-N interactions and the incorporation of both N and GP into VLPs. Our results support the conclusion that the interaction between Z and N is required for assembly of both the nucleocapsids and the glycoproteins into infectious arenavirus budding particles.
Comparison of the Pseudorabies Virus Us9 Protein with Homologs from Other Veterinary and Human Alphaherpesviruses
Authors: Lyman M. G. , Kemp C. D. , Taylor M. P. , Enquist L. W.
Published: May 2009

Pseudorabies virus (PRV) Us9 is a small, tail-anchored (TA) membrane protein that is essential for axonal sorting of viral structural proteins and is highly conserved among other members of the alphaherpesvirus subfamily. We cloned the Us9 homologs from two human pathogens, varicella-zoster virus (VZV) and herpes simplex virus type 1 (HSV-1), as well as two veterinary pathogens, equine herpesvirus type 1 (EHV-1) and bovine herpesvirus type 1 (BHV-1), and fused them to enhanced green fluorescent protein to examine their subcellular localization and membrane topology. Akin to PRV Us9, all of the Us9 homologs localized to the
trans
-Golgi network and had a type II membrane topology (typical of TA proteins). Furthermore, we examined whether any of the Us9 homologs could compensate for the loss of PRV Us9 in anterograde, neuron-to-cell spread of infection in a compartmented chamber system. EHV-1 and BHV-1 Us9 were able to fully compensate for the loss of PRV Us9, whereas VZV and HSV-1 Us9 proteins were unable to functionally replace PRV Us9 when they were expressed in a PRV background.
Elucidating and Minimizing the Loss by Recombinant Vaccinia Virus of Human Immunodeficiency Virus Gene Expression Resulting from Spontaneous Mutations and Positive Selection
Authors: Wyatt Linda S. , Earl Patricia L. , Xiao Wei , Americo Jeffrey L. , Cotter Catherine A. , Vogt Jennifer , Moss Bernard
Published: May 2009

While characterizing modified vaccinia virus recombinants (rMVAs) containing human immunodeficiency virus
env
and
gag
-
pol
genes, we detected nonexpressing mutants by immunostaining individual plaques. In many cases, the numbers of mutants increased during successive passages, indicating strong selection pressure. This phenomenon provided an opportunity to investigate the formation of spontaneous mutations in vaccinia virus, which encodes its own cytoplasmic replication system, and a challenge to reduce the occurrence of mutations for vaccine production. Analysis of virus from individual plaques indicated that loss of expression was due to frameshift mutations, mostly by addition or deletion of a single nucleotide in runs of four to six Gs or Cs, and large deletions that included MVA DNA flanking the recombinant gene. Interruption of the runs of Gs and Cs by silent codon alterations and moving the recombinant gene to a site between essential, highly conserved MVA genes eliminated or reduced frameshifts and viable deletion mutants, respectively. The rapidity at which nonexpressing mutants accumulated depended on the individual
env
and
gag
-
pol
genes and their suppressive effects on virus replication. Both the extracellular and transmembrane domains contributed to the selection of nonexpressing Env mutants. Stability of an unstable Env was improved by swapping external or transmembrane domains with a more stable Env. Most dramatically, removal of the transmembrane and cytoplasmic domains stabilized even the most highly unstable Env. Understanding the causes of instability and taking preemptive actions will facilitate the development of rMVA and other poxviruses as human and veterinary recombinant vaccines.
Genetic Characterization of Hepatitis B Virus in Peripheral Blood Leukocytes: Evidence for Selection and Compartmentalization of Viral Variants with the Immune Escape G145R Mutation
Authors: Datta Sibnarayan , Panigrahi Rajesh , Biswas Avik , Chandra Partha K. , Banerjee Arup , Mahapatra Pradip K. , Panda Chinmoy K. , Chakrabarti Shekhar , Bhattacharya Sujit K. , Biswas Kuntal , Chakravarty Runu
Published: May 2009

The compartmentalization of viral variants in distinct host tissues is a frequent event in many viral infections. Although hepatitis B virus (HBV) classically is considered hepatotropic, it has strong lymphotropic properties as well. However, unlike other viruses, molecular evolutionary studies to characterize HBV variants in compartments other than hepatocytes or sera have not been performed. The present work attempted to characterize HBV sequences from the peripheral blood leukocytes (PBL) of a large set of subjects, using advanced molecular biology and computational methods. The results of this study revealed the exclusive compartmentalization of HBV subgenotype Ae/A2-specific sequences with a potent immune escape G145R mutation in the PBL of the majority of the subjects. Interestingly, entirely different HBV genotypes/subgenotypes (C, D, or Aa/A1) were found to predominate in the sera of the same study populations. These results suggest that subgenotype Ae/A2 is selectively archived in the PBL, and the high prevalence of G145R indicates high immune pressure and high evolutionary rates of HBV DNA in the PBL. The results are analogous to available literature on the compartmentalization of other viruses. The present work thus provides evidence in favor of the compartment-specific abundance, evolution, and emergence of the potent immune escape mutant. These findings have important implications in the field of HBV molecular epidemiology, transmission, transfusion medicine, organ transplantation, and vaccination strategies.
Induction of Robust Cellular and Humoral Virus-Specific Adaptive Immune Responses in Human Immunodeficiency Virus-Infected Humanized BLT Mice
Authors: Brainard Diana M. , Seung Edward , Frahm Nicole , Cariappa Annaiah , Bailey Charles C. , Hart William K. , Shin Hae-Sook , Brooks Sarah F. , Knight Heather L. , Eichbaum Quentin , Yang Yong-Guang , Sykes Megan , Walker Bruce D. , Freeman Gordon J. , Pillai Shiv , Westmoreland Susan V. , Brander Christian , Luster Andrew D. , Tager Andrew M.
Published: May 2009

The generation of humanized BLT mice by the cotransplantation of human fetal thymus and liver tissues and CD34+fetal liver cells into nonobese diabetic/severe combined immunodeficiency mice allows for the long-term reconstitution of a functional human immune system, with human T cells, B cells, dendritic cells, and monocytes/macrophages repopulating mouse tissues. Here, we show that humanized BLT mice sustained high-level disseminated human immunodeficiency virus (HIV) infection, resulting in CD4+T-cell depletion and generalized immune activation. Following infection, HIV-specific humoral responses were present in all mice by 3 months, and HIV-specific CD4+and CD8+T-cell responses were detected in the majority of mice tested after 9 weeks of infection. Despite robust HIV-specific responses, however, viral loads remained elevated in infected BLT mice, raising the possibility that these responses are dysfunctional. The increased T-cell expression of the negative costimulator PD-1 recently has been postulated to contribute to T-cell dysfunction in chronic HIV infection. As seen in human infection, both CD4+and CD8+T cells demonstrated increased PD-1 expression in HIV-infected BLT mice, and PD-1 levels in these cells correlated positively with viral load and inversely with CD4+cell levels. The ability of humanized BLT mice to generate both cellular and humoral immune responses to HIV will allow the further investigation of human HIV-specific immune responses in vivo and suggests that these mice are able to provide a platform to assess candidate HIV vaccines and other immunotherapeutic strategies.
Initiation of Antiretroviral Therapy 48 Hours after Infection with Simian Immunodeficiency Virus Potently Suppresses Acute-Phase Viremia and Blocks the Massive Loss of Memory CD4
+
T Cells but Fails To Prevent Disease
Authors: Kubo Makoto , Nishimura Yoshiaki , Shingai Masashi , Lee Wendy , Brenchley Jason , Lafont Bernard , Buckler-White Alicia , Igarashi Tatsuhiko , Martin Malcolm A.
Published: May 2009

We investigated whether a 28-day course of potent antiretroviral therapy, initiated at a time point (48 h postinoculation) following simian immunodeficiency virus (SIV) inoculation when the acquisition of a viral infection was virtually assured, would sufficiently sensitize the immune system and result in controlled virus replication when treatment was stopped. The administration of tenofovir 48 h after SIV inoculation to six
Mamu-A*01
-negative rhesus macaques did, in fact, potently suppress virus replication in all of the treated rhesus macaques, but plasma viral RNA rapidly became detectable in all six animals following its cessation. Unexpectedly, the viral set points in the treated monkeys became established at two distinct levels. Three controller macaques had chronic phase virus loads in the range of 1 × 10
3
RNA copies/ml, whereas three noncontroller animals had set points of 2 × 10
5
to 8 × 10
5
RNA copies/ml. All of the noncontroller monkeys died with symptoms of immunodeficiency by week 60 postinfection, whereas two of the three controller animals were alive at week 80. Interestingly, the three controller macaques each carried major histocompatibility complex class I alleles that previously were reported to confer protection against SIV, and two of these animals generated cytotoxic T-lymphocyte escape viral variants during the course of their infections.
Modified state-surface approach to the study of unsaturated soil behavior. Part II: General formulation
Authors: Zhang Xiong , Lytton Robert L.
Published: May 2009

In the previous companion paper, a modified state-surface approach was proposed to algebraically represent unsaturated soil behavior under isotropic stress conditions. The present paper proposes a general theoretic formulation for the modified state-surface approach based on the theory proposed by Fredlund and co-workers. The signs and physical meanings of the material properties, the shapes of the loading–collapse (LC) and suction increase (SI) yield curves, and the mechanisms used in the Barcelona basic model (BBM) to model unsaturated soil behavior are discussed. Some other problems, such as stress-path independency and its implication on material properties, as well as coupling effects between the LC and SI curves, are also discussed. Based on analysis, it was found that with a minor modification, the modified state-surface approach can be used to study both unsaturated expansive and collapsible soil behavior in a unified framework.
Shear strength of unsaturated soil interfaces
Authors: Hamid Tariq B. , Miller Gerald A.
Published: May 2009

Unsaturated soil interfaces exist where unsaturated soil is in contact with structures such as foundations, retaining walls, and buried pipes. The unsaturated soil interface can be defined as a layer of unsaturated soil through which stresses are transferred from soil to structure and vice versa. In this paper, the shearing behavior of unsaturated soil interfaces is examined using results of interface direct shear tests conducted on a low-plasticity fine-grained soil. A conventional direct shear test device was modified to conduct direct shear interface tests using matric suction control. Further, the results were used to define failure envelopes for unsaturated soil interfaces having smooth and rough counterfaces. Results of this study indicate that matric suction contributes to the peak shear strength of unsaturated interfaces; however, postpeak shear strength did not appear to vary with changes in matric suction. Variations in net normal stress affected both peak and postpeak shear strength. Failure envelopes developed using the soil-water characteristic curve (SWCC) appeared to capture the nonlinear influence of matric suction on shear strength of soil and interfaces.
Bearing capacity under cyclic loading — offshore, along the coast, and on land. The 21st Bjerrum Lecture presented in Oslo, 23 November 2007This paper represents the written version of the 21st Bjerrum Lecture. While it has been edited for the present publication, it retains the general structure of the original lecture, which was intended for a general geotechnical audience. The Bjerrum Lecture is presented in Oslo in alternate years by the Norwegian Geotechnical Society with the support of the Bjerrum Memorial Fund (Laurits Bjerrums Minnefond).
Authors: Andersen Knut H.
Published: May 2009

Cyclic loading can be important for the foundation design of structures, both offshore, along the coast, and on land, and for the stability of slopes. This is illustrated by several examples. The paper discusses how soil behaves under cyclic loading, both for structures and for slopes, and shows that the cyclic shear strength and the failure mode under cyclic loading depend strongly on the stress path and the combination of average and cyclic shear stresses. Diagrams with the cyclic shear strength of clay, sand, and silt that can be used in practical design are presented. Comparisons between calculations and model tests indicate that foundation capacity under cyclic loading can be determined on the basis of cyclic shear strength determined in laboratory tests.
REFINED BPS STATE COUNTING FROM NEKRASOV'S FORMULA AND MACDONALD FUNCTIONS
Authors: AWATA HIDETOSHI , KANNO HIROAKI
Published: May 2009

It has been argued that Nekrasov's partition function gives the generating function of refined BPS state counting in the compactification of M theory on local Calabi–Yau spaces. We show that a refined version of the topological vertex we previously proposed (arXiv:hep-th/0502061) is a building block of Nekrasov's partition function with two equivariant parameters. Compared with another refined topological vertex by Iqbal, Kozcaz and Vafa (arXiv:hep-th/0701156), our refined vertex is expressed entirely in terms of the specialization of the Macdonald symmetric functions which is related to the equivariant character of the Hilbert scheme of points on ℂ2. We provide diagrammatic rules for computing the partition function from the web diagrams appearing in geometric engineering of Yang–Mills theory with eight supercharges. Our refined vertex has a simple transformation law under the flop operation of the diagram, which suggests that homological invariants of the Hopf link are related to the Macdonald functions.
A MODEL STUDY OF QUARK NUMBER SUSCEPTIBILITY AT FINITE CHEMICAL POTENTIAL AND ZERO TEMPERATURE
Authors: ZHANG YAN-BIN , HOU FENG-YAO , JIANG YU , SUN WEI-MIN , ZONG HONG-SHI
Published: May 2009

In this paper, we try to provide a direct method for calculating quark number susceptibility at finite chemical potential and zero temperature. In our approach, quark number susceptibility is totally determined by G[μ](p) (the dressed quark propagator at finite chemical potential μ). By applying the general result given in Phys. Rev. C71, 015205 (2005), G[μ](p) is calculated from the model quark propagator proposed in Phys. Rev. D67, 054019 (2003). From this the full analytic expression of quark number susceptibility at finite μ and zero T is obtained.
KNOTS AND PREONS
Authors: FINKELSTEIN ROBERT J.
Published: May 2009

It is shown that the four quantum trefoil solitons that are described by the irreducible representations [Formula: see text] of the quantum algebra SL q(2) [and that may be identified with the four families of elementary fermions (e, μ, τ; νeνμντ;d, s, b; u, c, t)] may be built out of three preons, chosen from two charged preons with charges (1/3, -1/3) and two neutral preons. These preons are fermions and are described by the [Formula: see text] representation of SL q(2). There are also four bosonic preons described by the [Formula: see text] and [Formula: see text] representations of SL q(2). The knotted standard theory may be replicated at the preon level and the conjectured particles are in principle indirectly observable.
RADIATIVE LEPTONIC DECAY OF Ds AND D MESONS
Authors: BARIK N. , NAIMUDDIN SK. , DASH P. C.
Published: May 2009

The radiative leptonic decays Ds → μνμγ and D → μνμγ are investigated at the tree level within the relativistic independent quark model based on the confining potential in the scalar–vector harmonic form. The branching ratios for these decays in the vanishing lepton mass limit are obtained as ℬr(Ds → μνμγ) = 4.94×10-4 and ℬr(D → μνμγ) = 3.34×10-5, which includes the contributions of the internal bremsstrahlung and structure dependent diagrams at the level of the quark constituents. Finally, the photon energy spectra as predicted here is found to be symmetric about the peak value of the photon energy at [Formula: see text].
CENTRAL COLLISIONS INDUCED BY LIGHT TARGET NUCLEI
Authors: BADAWY B. M.
Published: May 2009

For the interactions of p,3He ,4He , and6Li with emulsion at 4.5 A GeV/c, an experimental study has been performed. The type of interactions chosen was central, which enables to analyze a specific interaction mechanism. The selection of the central events has been in the framework of the particles emitted beyond the kinematic limits (θLab≥90°). This selection provides a strict criterion to distinguish the central collisions. For the sake of comparison, an additional criterion is introduced. It deals with interactions that exhibit an absence of projectile fragmentation. A detailed study of the emitted pions multiplicity is presented. The focusing is on the light emulsion target H and CNO in comparison with the heavy AgBr . The analysis reveals that the occultation of light projectile nuclei is possible in CNO targets along with the complete occultation in AgBr .
ANALYTICAL SOLUTIONS OF THE SCHRÖDINGER EQUATION WITH THE WOODS–SAXON POTENTIAL FOR ARBITRARY l STATE
Authors: BADALOV V. H. , AHMADOV H. I. , AHMADOV A. I.
Published: May 2009

In this work, the analytical solution of the radial Schrödinger equation for the Woods–Saxon potential is presented. In our calculations, we have applied the Nikiforov–Uvarov method by using the Pekeris approximation to the centrifugal potential for arbitrary l states. The bound state energy eigenvalues and corresponding eigenfunctions are obtained for various values of n and l quantum numbers.
INFRARED QCD
Authors: FRASCA MARCO
Published: May 2009

We prove that Nambu–Jona-Lasinio model is an exact description of infrared Quantum ChromoDynamics (QCD) deriving it from QCD Lagrangian. The model we obtain is renormalizable and confining but, taking very small momenta fixes completely all the parameters of the Nambu–Jona-Lasinio model through those of QCD. The choice of the infrared propagator is done consistently with recent numerical results from lattice and Dyson–Schwinger equations for Yang–Mills theory. The model we get coincides, once the ultraviolet contribution is removed, with the one proposed by Langfeld, Kettner and Reinhardt [Nucl. Phys. A608 (1996) 331].
EXISTENCE OF LONG-LIVED ISOTOPES OF A SUPERHEAVY ELEMENT IN NATURAL Au
Authors: MARINOV A. , RODUSHKIN I. , PAPE A. , KASHIV Y. , KOLB D. , BRANDT R. , GENTRY R. V. , MILLER H. W. , HALICZ L. , SEGAL I.
Published: May 2009

Evidence for the existence of long-lived isotopes with atomic mass numbers 261 and 265, and abundance of (1-10)×10-10relative to Au, has been found in a study of natural Au using inductively coupled plasma-sector field mass spectrometry. The measured masses match the predictions for the masses of261Rg and265Rg (Z=111), and those of some isobars of nearby elements. Based on chemical arguments, it is proposed that they are most probably isotopes of Rg. It is deduced that long-lived isomeric states exist in these isotopes. The hypothesis that they belong to a new class of long-lived high spin super- and hyperdeformed isomeric states is discussed.
On the growth of colloform textures: a case study of sphalerite from the Galmoy ore body, Ireland
Authors: Barrie Craig D. , Boyce Adrian J. , Boyle Alan P. , Williams Patrick J. , Blake Kevin , Wilkinson Jamie J. , Lowther Mike , McDermott Paul , Prior David J.
Published: May 2009

Colloform textures have been described from many of the world's sulphide ore deposits and involve formation of distinct microcrystalline layers. These textures provide information related to sequential stages of ore formation, yet their mechanism of growth is poorly understood. This study has analysed a series of colloform samples from the Galmoy Zn + Pb mine, Ireland. Results indicate that the growth sequence is not always intuitive and layers that appear stratigraphic upon cursory observation may not be. The crystal preferred orientation (CPO) of discrete colloform layers abruptly switches between different orientation axes. Examination of the same layers using
in situ
laser sulphur isotope analysis reveals equally striking changes in δ
34
S signature between end-member bacteriogenic (−25‰) and hydrothermal (+10‰) sources. Although these results, combined with petrographic observation, allow the determination of a probable growth history, there is no correlation between shifting CPO and δ
34
S signature. Trace element analysis reveals changes in trace element sequestration between colloform layers. Cadmium- and chlorine-rich layers correspond to a hydrothermal sulphur source, whereas iron-rich layers correspond to a bacteriogenic sulphur source. In the absence of alternative mechanisms we suggest that the most likely factors influencing CPO changes are temperature and degree of supersaturation during two-fluid mixing.
Early Jurassic normal faulting in a carbonate extensional basin: characterization of tectonically driven platform drowning (High Atlas rift, Morocco)
Authors: Lachkar Nadifa , Guiraud Michel , Harfi Abdelghani El , Dommergues Jean-Louis , Dera Guillaume , Durlet Christophe
Published: May 2009

This paper describes a tectonostratigraphic model of the synrift evolution of the Early Jurassic High Atlas rift of Morocco. The model is constrained by mapping of a set of inverted extensional blocks, by facies analysis of carbonate platform and turbiditic to hemipelagic synrift deposits, and by high-resolution (
n
× 100 ka) biostratigraphy of the Early Jurassic succession. The chronostratigraphic packages of the High Atlas of Rich vary significantly in thickness, facies and architecture from one tectonic block to another. Our study shows how synrift strain varied in space and time over a long time interval (14 Ma) around the High Atlas rift. Initially, in Sinemurian time, the High Atlas rift was affected by low-strain normal faulting that controlled the growth of an extensive, low-gradient carbonate platform, except in the northern domain (towards the rift axis), where hemipelagic deposition related to high-rate faulting prevailed. Subsequently, in Carixian–Domerian time, a rapid increase in accommodation space and block subsidence caused by high-strain normal faulting brought about localized drowning of the carbonate platform and the development of calciturbidites and of starved deposits towards the rift axis. During this interval, high-strain, upper-crustal normal faulting migrated rapidly (over a period of 5 Ma) towards the rift periphery.
Early Ordovician rifting of Avalonia and birth of the Rheic Ocean: U–Pb detrital zircon constraints from Newfoundland
Authors: Pollock Jeffrey C. , Hibbard James P. , Sylvester Paul J.
Published: May 2009

Avalonia is the largest accreted crustal block in the Appalachian orogen and comprises a collection of late Neoproterozoic volcano-sedimentary sequences that are overlain by a Palaeozoic platformal sedimentary succession. Detrital zircons from the Conception Group are dominated by 570–620 Ma ages and contain a significant component generated by erosion of coeval igneous arc-volcanic rocks. Overlying samples from the Cuckold and Crown Hill formations are dominated by Neoproterozoic populations with ages between 600 and 650 Ma and are interpreted to be derived from the underlying calc-alkaline arc-plutonic rocks. Early Palaeozoic platform units are dominated by
c
. 620 Ma zircons with lesser Mesoproterozoic and Palaeoproterozoic zircons. The range of detrital zircon ages is inconsistent with a West African provenance and suggests that Avalonia originated along the Gondwanan margin of the Amazon craton. The influx of Mesoproterozoic and Palaeoproterozoic detritus in the Avalonian platform suggests a major change in tectonic regime. The prominent change in provenance is interpreted to be related to separation of Avalonia from Gondwana during the Early Ordovician opening of the Rheic Ocean. The Redmans Formation is interpreted to represent the rift–drift transition of the Rheic Ocean, which imposes important constraints on the palaeotectonic evolution of Avalonia.

Supplementary material:

U–Pb isotopic data of LA-ICP-MS analysis of detrital zircons are available at
http://www.geolsoc.org.uk/SUP18346
.
Devonian arc-related magmatism in the Tseel terrane of SW Mongolia: chronological and geochemical evidence
Authors: Demoux Antoine , Kröner Alfred , Hegner Ernst , Badarch Gombosuren
Published: May 2009

The Tseel terrane in the Gobi Desert of SW Mongolia consists of a composite crustal segment of imbricated sheets of high- and low-grade metamorphic rocks of predominantly middle Palaeozoic age. New sensitive high-resolution ion microprobe (SHRIMP) zircon ages of 396 ± 3 Ma (2σ) and 397 ± 3 Ma (2σ) for two calc-alkaline metarhyolite samples indicate arc volcanism during the early Devonian. An undeformed feldspar porphyry cross-cutting the early Devonian low-grade sequence yielded an emplacement age of 279 ± 2 Ma (2σ). Geochemical and Nd isotopic data for low-grade mafic metavolcanic rocks are consistent with melting of moderately depleted upper mantle sources in a transitional arc–back-arc setting. In addition, there are high- and low-grade felsic metaigneous rocks with subduction-related chemical signatures and heterogeneous Nd isotopic compositions indicating an origin from mixed sources, including juvenile and Precambrian crustal components. The field observations combined with the geochemical and isotopic data suggest that the Tseel terrane represents a segment of a mature Japan-type arc associated with a juvenile back-arc basin.

Supplementary material:

Latitudes and longitudes of sample localities, major- and trace-element abundances for rock samples, data for reference materials obtained by LA-ICP-MS and Sm–Nd isotopic data for rock samples are available at
http://www.geolsoc.org.uk/SUP18338
.
Crustal affinities in the Arctic Uralides, northern Russia: significance of detrital zircon ages from Neoproterozoic and Palaeozoic sediments in Novaya Zemlya and Taimyr
Authors: Pease V. , Scott R.A.
Published: May 2009

U–Pb ion microprobe detrital zircon provenance investigations of pre-Mesozoic sediment samples from southern Novaya Zemlya and northern Taimyr, Arctic Russia, provide new constraints on the tectonic evolution of northern Eurasia. Sediments from both areas previously assigned a Neoproterozoic age are shown to be Palaeozoic (≤500 Ma), changing our understanding of the timing of tectonic events and their regional correlation. Samples from Novaya Zemlya provide an
a priori
Baltica signature, and dominant cumulative probability age peaks between 610 and 530 Ma are consistent with derivation from Timanide sources. Samples from northern Taimyr also contain the unique Timanian ’fingerprint' and are also inferred to be derived from the continental slope of northeastern Baltica, implying that the North Kara block was a part of Baltica in the early Palaeozoic. These data constrain the timing of deformation, metamorphism and development of an unconformity in southern Novaya Zemlya to a restricted period no earlier than late Cambrian–early Ordovician and at least 50 Ma after the peak Timanian event. The unconformity on Novaya Zemlya can be correlated in style and timing with an unconformity on Severnaya Zemlya and may record post-Timanian extensional collapse and onset of spreading in the Uralian Ocean.

Supplementary material:

U–Th–Pb ion-microprobe analytical results are available at
http://www.geolsoc.org.uk/SUP18340
.
A strike-slip terrane boundary in Wedel Jarlsberg Land, Svalbard, and its bearing on correlations of SW Spitsbergen with the Pearya terrane and Timanide belt
Authors: Mazur Stanisław , Czerny Jerzy , Majka Jarosław , Manecki Maciej , Holm Daniel , Smyrak Aleksandra , Wypych Alicja
Published: May 2009

Southwest Spitsbergen, Wedel Jarlsberg Land, consists of two Proterozoic terranes with differing structural and metamorphic histories. The northern terrane experienced two Early Palaeozoic deformation events both accompanied by greenschist-facies metamorphism of similar grade. The southern terrane records a Neoproterozoic pervasive amphibolite-facies metamorphism and strong deformational fabric only locally retrogressed during a Caledonian greenschist-grade event. These terranes are separated by an important sinistral ductile shear zone defined as the Vimsodden–Kosibapasset zone, which comprises wrench- and contraction-dominated domains characteristic of strain partitioning in transpression zones; in this case apparently controlled by contrasting rheologies of the juxtaposed crustal domains. The northern terrane of Wedel Jarlsberg Land shares affinities with Pearya in northern Ellesmere Island of Arctic Canada whereas the southern one resembles the Timanide belt of NE Europe. A quantitative approach facilitated by a numerical plate model demonstrates that correlation with Pearya is feasible if sinistral displacement ofc. 600 km occurred during the Caledonian orogeny. The correlation with the Timanides is valid if the southern terrane represents an outlier of the Timanide belt separated from Baltica by the opening of the Iapetus Ocean.
Subduction in the Western Makran: the historian's contribution
Authors: Musson R.M.W.
Published: May 2009

The Makran subduction zone, which runs along the southeastern coast of Iran and the southern coast of Pakistan, is a major control on the seismic hazard of the region. Whereas the eastern part of this zone has been active in recent historical times, the western part has not. This could indicate a zone currently locked, or it could be that subduction is occurring aseismically or not at all. Evidence for large thrust activity rests on one event, apparently very large, in 1483. Historical research, especially taking into consideration the political situation in the region at the end of the 15th century, suggests that this 1483 event was a moderate magnitude earthquake in the vicinity of Qeshm Island that has been misassociated with a second, later, earthquake. This interpretation removes from the earthquake catalogue any evidence for major earthquake activity along the Western Makran, and adds weight to the tectonic interpretation that major seismicity has a westerly termination at the Sonne Fault. This presents an interesting example of how a piece of obscure historical information has a significant effect on resolving a question of tectonic interpretation, and with it, influences the estimation of regional seismic hazard, including tsumani hazard in the Indian Ocean.
Protein tyrosine phosphatase-α complexes with the IGF-I receptor and undergoes IGF-I-stimulated tyrosine phosphorylation that mediates cell migration
Authors: Chen Shirley C. , Khanna Ranvikram S. , Bessette Darrell C. , Samayawardhena Lionel A. , Pallen Catherine J.
Published: May 2009

Protein tyrosine phosphatase-α (PTPα) is a widely expressed receptor-type phosphatase that functions in multiple signaling systems. The actions of PTPα can be regulated by its phosphorylation on serine and tyrosine residues, although little is known about the conditions that promote PTPα phosphorylation. In this study, we tested the ability of several extracellular factors to stimulate PTPα tyrosine phosphorylation. The growth factors IGF-I and acidic FGF induced the highest increase in PTPα phosphorylation at tyrosine 789, followed by PMA and lysophosphatidic acid, while EGF had little effect. Further investigation of IGF-I-induced PTPα tyrosine phosphorylation demonstrated that this occurs through a novel Src family kinase-independent mechanism that does not require focal adhesion kinase, phosphatidylinositol 3-kinase, or MEK. We also show that PTPα physically interacts with the IGF-I receptor. In contrast to IGF-I-induced PTPα phosphorylation, this association does not require IGF-I. The interaction of PTPα and the IGF-I receptor is independent of PTPα catalytic activity, and expression of exogenous PTPα does not promote IGF-I receptor tyrosine dephosphorylation, indicating that PTPα does not act as an IGF-I receptor phosphatase. However, PTPα mediates IGF-I signaling, because IGF-I-stimulated fibroblast migration was reduced by ∼50% in cells lacking PTPα or in cells with mutant PTPα lacking the tyrosine 789 phosphorylation site. Our results suggest that PTPα tyrosine phosphorylation can occur in response to diverse stimuli and can be mediated by various tyrosine kinases. In the case of IGF-I, we propose that IGF-I-induced tyrosine 789 phosphorylation of PTPα, possibly catalyzed by the PTPα-associated IGF-I receptor tyrosine kinase, is required for efficient cell migration in response to this growth factor.
Histamine hyperpolarizes human glioblastoma cells by activating the intermediate-conductance Ca2+-activated K+channel
Authors: Fioretti Bernard , Catacuzzeno Luigi , Sforna Luigi , Aiello Francesco , Pagani Francesca , Ragozzino Davide , Castigli Emilia , Franciolini Fabio
Published: May 2009

The effects of histamine on the membrane potential and currents of human glioblastoma (GL-15) cells were investigated. In perforated whole cell configuration, short (3 s) applications of histamine (100 μM) hyperpolarized the membrane by activating a K+-selective current. The response involved the activation of the pyrilamine-sensitive H1receptor and Ca2+release from thapsigargin-sensitive intracellular stores. The histamine-activated current was insensitive to tetraethylammonium (3 mM), iberiotoxin (100 nM), and d-tubocurarine (100 μM) but was markedly inhibited by charybdotoxin (100 nM), clotrimazole (1 μM), and 1-[(2-chlorophenyl)diphenylmethyl]-1H-pyrazole (TRAM-34, 1 μM), a pharmacological profile congruent with the intermediate conductance Ca2+-activated K+(IKCa) channel. Cell-attached recordings confirmed that histamine activated a K+channel with properties congruent with the IKCachannel (voltage independence, 22 pS unitary conductance and slight inward rectification in symmetrical 140 mM K+). More prolonged histamine applications (2–3 min) often evoked a sustained IKCachannel activity, which depended on a La2+(10 μM)-sensitive Ca2+influx. Intracellular Ca2+measurements revealed that the sustained IKCachannel activity enhanced the histamine-induced Ca2+signal, most likely by a hyperpolarization-induced increase in the driving force for Ca2+influx. In virtually all cells examined we also observed the expression of the large conductance Ca2+-activated K+(BKCa) channel, with a unitary conductance of ca. 230 pS in symmetrical 140 mM K+, and a Ca2+dissociation constant [ KD(Ca)] of ca. 3 μM, at −40 mV. Notably in no instance was the BKCachannel activated by histamine under physiological conditions. The most parsimonious explanation based on the different KD(Ca)for the two KCachannels is provided.
ROS activate KCl cotransport in nonadherent Ehrlich ascites cells but K+ and Cl− channels in adherent Ehrlich Lettré and NIH3T3 cells
Authors: Lambert Ian Henry , Klausen Thomas Kjær , Bergdahl Andreas , Hougaard Charlotte , Hoffmann Else Kay
Published: May 2009

Addition of H2O2 (0.5 mM) to Ehrlich ascites tumor cells under isotonic conditions results in a substantial (22 ± 1%) reduction in cell volume within 25 min. The cell shrinkage is paralleled by net loss of K+, which was significant within 8 min, whereas no concomitant increase in the K+ or Cl− conductances could be observed. The H2O2-induced cell shrinkage was unaffected by the presence of clofilium and clotrimazole, which blocks volume-sensitive and Ca2+-activated K+ channels, respectively, and is unaffected by a raise in extracellular K+ concentration to a value that eliminates the electrochemical driving force for K+. On the other hand, the H2O2-induced cell shrinkage was impaired in the presence of the KCl cotransport inhibitor (dihydro-indenyl)oxyalkanoic acid (DIOA), following substitution of NO3− for Cl−, and when the driving force for KCl cotransport was omitted. It is suggested that H2O2 activates electroneutral KCl cotransport in Ehrlich ascites tumor cells and not K+ and Cl− channels. Addition of H2O2 to hypotonically exposed cells accelerates the regulatory volume decrease and the concomitant net loss of K+, whereas no additional increase in the K+ and Cl− conductance was observed. The effect of H2O2 on cell volume was blocked by the serine-threonine phosphatase inhibitor calyculin A, indicating an important role of serine-threonine phosphorylation in the H2O2-mediated activation of KCl cotransport in Ehrlich cells. In contrast, addition of H2O2 to adherent cells, e.g., Ehrlich Lettré ascites cells, a subtype of the Ehrlich ascites tumor cells, and NIH3T3 mouse fibroblasts increased the K+ and Cl− conductances after hypotonic cell swelling. Hence, H2O2 induces KCl cotransport or K+ and Cl− channels in nonadherent and adherent cells, respectively.
Transfer of ascorbic acid across the vascular endothelium: mechanism and self-regulation
Authors: May James M. , Qu Zhi-chao , Qiao Huan
Published: May 2009

To determine how ascorbic acid moves from the bloodstream into tissues, we assessed transfer of the vitamin across the barrier generated by EA.hy926 endothelial cells when these were cultured on semipermeable filter supports. Ascorbate transfer from the luminal to the abluminal compartment was time dependent, inhibited by anion channel blockers and by activation of protein kinase A, but was increased by thrombin. Ascorbate transfer occurred by a paracellular route, since it did not correlate with intracellular ascorbate contents and was not rectified or saturable. Nonetheless, intracellular ascorbate inhibited the transfer of both ascorbate and radiolabeled inulin across the endothelial barrier. The increase in barrier function due to ascorbate was dependent on its intracellular concentration, significant by 15 min of incubation, prevented by the cytoskeletal inhibitor colchicine, associated with F-actin stress fiber formation, and not due to collagen deposition. These results show that ascorbate traverses the endothelial barrier by a paracellular route that is regulated by cell metabolism, ion channels, and ascorbate itself. Since the latter effect occurred over the physiological range of ascorbate plasma concentrations, it could reflect a role for the vitamin in control of endothelial barrier function in vivo.
Vascular endothelial growth factor receptor inhibitor enhances dietary salt-induced hypertension in Sprague-Dawley rats
Authors: Gu Jian-Wei , Manning R. Davis , Young Emily , Shparago Megan , Sartin Brandi , Bailey Amelia Purser
Published: May 2009

Clinical evidence links the inhibition of VEGF to hypertension. However, the mechanisms by which VEGF affects the pathogenesis of hypertension remain in question. We determined 1) whether administration of VEGF receptor inhibitor SU5416 enhances dietary salt-induced hypertension in Sprague-Dawley (SD) rats, and 2) whether VEGF or SU5416 directly affects proliferation of cultured human renal proximal tubular epithelial cells (HRPTEC) and endothelial nitric oxide synthase (eNOS) expression in cultured human glomerular microvessel endothelial cells (HGMEC). Ten 10-wk-old male SD rats received a high sodium diet (HS; 8%) and the other 10 SD rats received a normal sodium diet (NS; 0.5%) for 4 wks. After 2 wks of the dietary program, five rats were administered with SU5416 at 10 mg·kg−1·day−1ip or DMSO (vehicle) for 14 days in HS and NS groups. Mean arterial pressure was significantly higher in rats treated with SU5416, as opposed to those treated with DMSO and fed with HS for 4 wk (157.6 ± 3.9 vs. 125.9 ± 4.3 mmHg, P < 0.01). Increased proteinuria and albuminuria were associated with marked renal histological abnormalities in HS group with SU5416 administration, compared with those in the vehicle HS group. 3H-thymidine incorporation assay showed that SU5416 blocked the actions of both exogenous and endogenous VEGF on the proliferation of HRPTEC. VEGF (10 ng/ml) significantly increased eNOS protein levels by 29% in cultured HGMEC, but its action was completely abolished by SU5416. These results suggest that VEGF receptor inhibition enhances dietary salt-induced hypertension and kidney injury, possibly by direct damage on renal cells and decreasing NO production by eNOS.
Sexual dimorphism in glomerular arginine transport affects nitric oxide generation in old male rats
Authors: Schwartz Idit F. , Chernichovski Tamara , Krishtol Natalia , Grupper Avishai , Laron Ido , Schwartz Doron
Published: May 2009

Animal models suggest that decreased renal endothelial nitric oxide synthase (eNOS) activity in old males promotes renal injury, whereas females are protected. We aimed to explore whether aging alters glomerular arginine uptake by CAT-1, the selective arginine supplier to eNOS in rats. Arginine uptake by glomeruli from young males (3 mo) was significantly higher than in young females. Old males (19 mo) exhibited a significant decrease in arginine transport compared with young males, whereas no differences were observed between old and young females. CAT-1 abundance remained unchanged in all experimental groups. The abundance of PKCα (CAT-1 inhibitor) was significantly augmented in young females vs. young males, old vs. young males, and in old females vs. old males. No differences in PKCα content were detected between old and young females. Phosphorylated PKCα was significantly increased in old rats from both genders. αTocopherol, a PKC inhibitor, produced a significant increase in arginine transport and restored NO generation in old males only. Ex vivo incubation of glomeruli from old males with PMA (PKC stimulant) significantly attenuated the effect of tocopherol on arginine uptake. In conclusion, attenuated glomerular arginine transport by CAT-1 contributes to the age-dependent, NO-deficient state in old male rats through upregulation of PKCα. In old females glomerular arginine transport is protected from the effects of PKCα by an unknown mechanism.