bluuebunny/crossref_metadata_2025 huggingface dataset:
LISPB DELTA, a lithospheric seismic profile in Britain: analysis and interpretation of the Wales and southern England section
Authors: Maguire Peter , England Richard , Hardwick Anthony
Published: January 2011

The Lithospheric Seismic Profile in Britain (LISPB), shot in 1974, included a 310 km profile LISPB DELTA, crossing the Palaeozoic Welsh Basin, the western extent of the Midland microcraton and the Cornubian zone of southern England. This first comprehensive analysis of these data has produced a sub-horizontally layered seismic and associated gravity model that correlates well with surface geology. A north–south decrease in crustal velocity and density corresponds to the change from Avalonian crust into the Rheno-Hercynian zone at the south end of the profile. High velocities and densities in the lowest crustal layer beneath north Wales are proposed to result from Cenozoic and possibly Ordovician igneous intrusive rocks, the former derived from an upwelling plume associated with the opening of the North Atlantic. Examination of the load distribution throughout the model shows that it is strongly correlated with the earthquake distribution along LISPB DELTA. Earthquake focal depth also correlates with heat flow. A simple heat-flow profile has been derived, and the seismic velocity model used to constrain crustal heat production values. A long-wavelength excursion from published data can be explained in terms of an increase in mantle heat flow resulting from a previously identified deep thermal anomaly beneath the Irish Sea.

Supplementary material:

normalised, synthetic and true amplitude seismic record sections including picks and modelled phases for shots SP04, SP05, SPS1, SPS2 are available at http://www.geolsoc.org.uk/SUP18450.
Pb-isotopic evidence for rapid trench-parallel mantle flow beneath Vanuatu
Authors: Heyworth Z. , Knesel K.M. , Turner S.P. , Arculus R.J.
Published: January 2011

Recent geophysical and geochemical studies suggest that some subduction zones have a significant component of trench-parallel flow that is difficult to reconcile with conventional 2D corner-flow models. Mapping of different mantle Pb-isotopic signatures provides an opportunity to assess the role of along-strike flow beneath the Vanuatu region. Young back-arc spreading centres in the southern segment of the subduction zone have high
208
Pb/
204
Pb for a given
206
Pb/
204
Pb, similar to the Indian-type mantle signatures of present-day volcanoes in the central segment of the arc, but distinct from adjacent southern-arc volcanoes with Pacific-like mantle traits. This configuration indicates that convection in the mantle wedge beneath Vanuatu is dominated by southward flow parallel to the trench, rather than pure corner flow induced by viscous drag along the upper surface of the subducting plate. We propose that this southward flow is related to pressure gradients developed during asymmetric rollback of the Australian plate. Trench-parallel flow rates in Vanuatu are estimated at 10–28 cm a
−1
, further highlighting that along-strike flow can exceed the convergence-parallel mantle motions predicted from conventional 2D corner-flow models.
Reconciling deep seismogenic and shallow active faults through analogue modelling: the case of the Messina Straits (southern Italy)
Authors: Bonini Lorenzo , Bucci Daniela Di , Toscani Giovanni , Seno Silvio , Valensise Gianluca
Published: January 2011

The catastrophic 28 December 1908, M
w
7.1, Messina Straits earthquake was generated by a large, low-angle, SE-dipping, blind normal fault. A number of shallow, high-angle normal faults arranged in a graben-like fashion occur in the same area both on land and offshore, reaching the surface and in some instances affecting recent deposits. These faults are normally interpreted as active and have often been considered potentially seismogenic. We used an analogue modelling approach to simulate the evolution of a large, low-angle normal fault and investigate its relationships with the overlying secondary faults. We find that these faults represent the brittle surface expression of the long-term activity of the underlying master fault, and that all faults mapped by previous workers in the Messina Straits are compatible with sustained slip along the fault responsible for the 1908 earthquake. Our results confirm that analogue modelling provides a useful tool to investigate the evolution and the hierarchical relationships of fault systems, suggesting that this approach is effective in the investigation of complex seismogenic areas.
Cambrian successions of the Meguma Terrane, Nova Scotia, and Harlech Dome, North Wales: dispersed fragments of a peri-Gondwanan basin?
Authors: Waldron John W.F. , Schofield David I. , White Chris E. , Barr Sandra M.
Published: January 2011

The Meguma Terrane of Nova Scotia and the Harlech Dome of North Wales preserve similar sedimentary successions of Cambrian age. Both successions comprise a thick succession of early Cambrian sandstone turbidites, overlain by early to middle Cambrian alternating mud-rich and sand-rich units in which manganese is concentrated in two stratigraphic intervals. Above these, both successions comprise anoxic, organic-rich turbidites, shallowing upward into paler, more bioturbated Tremadocian mudstone with
Rhabdinopora
. Within the limited constraints of the available biostratigraphic and geochronological data, major changes in environment occurred synchronously in the two successions. Both successions show much greater similarity to each other than to adjacent successions on ‘Avalonia'. A detrital zircon analysis from the Rhinog Formation, low in the Harlech Dome succession, reveals distinct clusters of ages around 537 Ma and 2.0–2.1 Ga. A close similarity to analyses from the Meguma Terrane suggests proximity between the two terranes on the margin of Gondwana during the Cambrian Period. We suggest the term Megumia for the palaeogeographical domain that included the two successions, which was dispersed during subsequent Appalachian and Caledonian movements. These observations suggest that Megumia may have separated terranes previously regarded as parts of Avalonia.

Supplementary material:

U/Pb detrital zircon analytical data are available at
http://www.geolsoc.org.uk/SUP18431
.
Seismic interpretation of the Laga basin; constraints on the structural setting and kinematics of the Central Apennines
Authors: Bigi S. , Casero P. , Ciotoli G.
Published: January 2011

The Messinian Laga basin is the largest foreland basin within the Central Apennines fold and thrust belt (Italy). This area, actively investigated in the 1980s and 1990s for hydrocarbon resources, is considered a valuable analogue for clastic reservoirs developed in confined structural settings. Furthermore, it represents a key area for understanding the evolution of the Apennines, as it links the internal, structurally uplifted Early Miocene fold and thrust belt of the western Central Apennines with the more external and recent belt to the east. Despite several papers published on this area, the only reconstruction of the substratum structure is an internal and classified industry report. During the present study, we had access to a seismic database comprising 200 km of seismic profiles that were collected between 1983 and 1990. These data allowed us to reconstruct the structural setting of the Laga basin substratum, define the lateral continuity of the main compressional structures within the basin, construct a balanced cross-section, and define the shortening values.
'As We May Think' at 65
Authors: Harper Simon
Published: January 2011

At 65 'As We May Think' has reached its pensionable age but as yet is showing no signs of retiring. As a researcher within the Web Science and Hypertext domains, and as a member of SIGWEB, I already know who Vannevar Bush is and understand the importance of his work to my field. I know that he proposed the MEMEX, an analogue information system using microfilm which is seen as the distant forerunner to our current hypertext systems, and indeed, the World Wide Web. Luminaries such as Theodor Holm Nelson and Doug Engelbart have credited Bush as being the inspiration for their own work in hypertext and distributed systems such as the Web. So what more can we say about Vannevar Bush and the work which spurred the creation of the Hypertext field. It seems to me that Bush's main ideas have never been more important than they are today. Indeed, the idea of association and its importance for the automation and augmentation of human thought and cognition still has resonance even today. Indeed, these concepts and the solutions they imply have become even more important than when they where first conceived, and throughout the 50s and 60s.
The cloud
Authors: Pan Yue , Blevis Eli
Published: January 2011

The forum title "Sustainably Ours" was chosen to suggest two things about sustainability. First, sustainability is collectively ours---it is an issue of collective global fate accumulated from individual and sovereign actions. Second, our CHI community is especially responsible for certain issues of and approaches to sustainability---how interactivity is implicated in material effects, behavioral change, changing sociopolitical contexts of design, and mitigation of and adaptation to climate change.

Eli Blevis, Editor | eblevis@indiana.edu
The need for video in scientific communication
Authors: Löwgren Jonas
Published: January 2011

"The ground was shaking as the vehicle walked past me."
Design and public policy considerations for accessible e-book readers
Authors: Danielsen Chris , Taylor Anne , Majerus Wesley
Published: January 2011

Public policy increasingly plays a role in influencing the work that we do as HCI researchers, interaction designers, and practitioners. "Public policy" is a broad term that includes both government policy and policy within non-governmental organizations, such as standards bodies. The "Interacting with Public Policy" forum focuses on topics at the intersection of human-computer interaction and public policy.

        

Jonathan Lazar, Editor | JLazar@towson.edu
A social community based approach for reducing the propagation of infectious diseases in healthcare
Authors: Yang Jie , Ren Yanzhi , Chen Yingying , Chuah Mooi Choo
Published: January 2011

In this work, we investigate the feasibility and effectiveness of using human contact traces collected from mobile phones to derive social community information to reduce the disease propagation rate in the healthcare domain. Our trace-driven simulation results showed that our scheme is highly effective, and thus opens more opportunities for utilizing social relationships information to support healthcare related applications.
BeamAdapt
Authors: Yu Hang , Zhong Lin , Sabharwal Ashutosh
Published: January 2011

All current mobile devices are omni directional in transmission, which not only limits device energy efficiency but also poses a significant challenge toward network capacity through inter-link interference. In this work, we make mobile devices directional with beamsteering. By allowing a dynamic number of antennas in beamsteering, we reveal an important tradeoff between device energy efficiency and network capacity. We then provide a distributed algorithm called BeamAdapt that allows each mobile device in the network to closely approach the optimal tradeoff, with minimum aggregated device power to achieve certain network capacity. We also offer a cellular system realization of BeamAdapt as well as a Qualnet-based evaluation. The results show the effectiveness of BeamAdapt in device power reduction without sacrificing network throughput.
Caché
Authors: Amini Shahriyar , Lindqvist Janne , Hong Jason I. , Mou Maladau , Raheja Rahul , Lin Jialiu , Sadeh Norman , Tochb Eran
Published: January 2011

Location-enhanced content while useful for mobile users can also be harmful for their privacy. We present feasibility analysis and preliminary evaluation of Caché, an approach for preserving mobile users' privacy by caching location-enhanced content in advance.
DataSpotting
Authors: Bao Xuan , Lee Uichin , Rimac Ivica , Choudhury Romit R.
Published: January 2011

Mobile broadband demand keeps growing at an overwhelming pace. Though emerging wireless technologies will provide more bandwidth, the increase in demand may easily consume the extra bandwidth. To alleviate this problem, we propose using the content available on individual devices as caches. Particularly, when a user reaches areas with dense clusters of mobile devices, "data spots", the operator can instruct the user to connect with other users sharing similar interests and serve the requests locally. This paper presents feasibility study as well as prototype implementation of this idea.
Dynamic channel reservations for wireless multihop communications
Authors: Yi Jun , Poellabauer Christian , Hu Xiaobo Sharon , Chantem Thidapat , Zhang Liqiang
Published: January 2011

Providing real-time service in an energy efficient manner in wireless multihop networks is an important and challenging problem. However, existing medium access control schemes are either over-coordinated (fixed-schedule-based schemes) or under-coordinated (prioritized contention-based schemes), failing to address this problem efficiently. This paper introduces a new medium access scheme, called FrugalMAC, aiming to provide timely, ondemand, and contention-free medium access by relying on a progressive, dynamic reservation mechanism coupled with reservation vectors. A node sleeps whenever the channel is not needed for data communication and slot reservation. In addition, FrugalMAC employs reservation pipelining and an admission control mechanism to support end-to-end real-time stream delivery. We have implemented a prototype of FrugalMAC in our sensor network testbed. Our preliminary results show that FrugalMAC has high energy efficiency and effectively supports timeliness.
A 40-Year Journey in Search of Selective Antiviral Chemotherapy*
Authors: De Clercq Erik
Published: January 2011

My search for a selective antiviral chemotherapy started more than 40 years ago with interferon inducers, then shifted to nucleoside analogs with the discovery of BVDU (brivudin), a highly selective anti-HSV-1 and anti-VZV agent, and to dideoxynucleoside analogs such as d4T (stavudine), anti-HIV agents. The search culminated in the discovery of acyclic nucleoside phosphonates (ANPs) (in collaboration with Antonin Holý), a key class of compounds active against HIV, hepatitis B virus, and DNA viruses at large; the best known of these compounds is tenofovir. Along the way, the principle of the non-nucleoside reverse transcriptase inhibitors (NNRTIs) was established. This work, initiated in collaboration with the late Paul A.J. Janssen, eventually led to the identification of rilpivirine as perhaps an “ideal” NNRTI.
Spatiotemporal Regulation of Small GTPases as Revealed by Probes Based on the Principle of Förster Resonance Energy Transfer (FRET): Implications for Signaling and Pharmacology
Authors: Kiyokawa Etsuko , Aoki Kazuhiro , Nakamura Takeshi , Matsuda Michiyuki
Published: January 2011

Low molecular weight (“small”) GTPases are key regulators of a number of signaling cascades. Each GTPase is regulated by numerous guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs), and each GTPase binds to numerous effector proteins in a GTP-dependent manner. In many instances, individual regulators activate more than one GTPase, and each effector binds to one or more GTPases belonging to the same family. To untangle these complex networks, probes based on the principle of Förster resonance energy transfer (FRET) are widely used. Here, we provide an overview of the probes based on FRET and examples of discoveries achieved with them. In the process, we attempt to delineate the merits, current limitations, and future applications of this technique to pharmacological studies.
Mechanisms of Monoclonal Antibody–Drug Interactions
Authors: Zhou Honghui , Mascelli Mary Ann
Published: January 2011

The concept of monoclonal antibodies (mAbs) as pharmacotherapeutics was validated in the mid-1980s with the successful clinical development of the fully murine mAb muromonab-CD3 for prevention of acute organ rejection. However, clinical applications of fully murine mAbs are restricted, owing to the high incidence of serious immune-mediated side effects, particularly upon repeated exposure. The rate and severity of immune-mediated toxicities of these agents were significantly attenuated by the development of mouse/human chimeric, fully human, and humanized mAbs. These refinements in molecular structure allowed repeated, long-term administration, where therapeutically warranted, which, in turn, broadened the scope of indications for this class of therapy. Presently, numerous mAbs are approved or are undergoing clinical evaluation for treatment of oncologic and chronic inflammatory diseases. The current experimental development landscape spans respiratory, metabolic, and central nervous system disorders as well as infectious disease. A consequence of the expanding numbers of mAb indications is concomitant administration of these agents with established small molecule pharmacotherapies, which necessitates a comprehensive understanding of mAb–small molecule drug interactions as well as mAb-mAb interactions. Current knowledge indicates that mAbs do not elicit a direct effect on the metabolic/clearance pathways for small molecular therapeutics. However, the immunomodulatory properties of mAbs can indirectly alter clearance of certain small molecule entities through the attenuation of noncatabolic enzymatic pathways.
Bioactivation of Drugs: Risk and Drug Design
Authors: Walsh John S. , Miwa Gerald T.
Published: January 2011

Bioactivation through drug metabolism is frequently suspected as an initiating event in many drug toxicities. The CYP450 and peroxidase enzyme systems are generally considered the most important groups of enzymes involved in bioactivation, producing either electrophilic or radical metabolites. Drug design efforts routinely consider these factors, and a number of structural alerts for bioactivation have been identified. Among the most frequently encountered structural alerts are aromatic systems with electron-donating substituents and some five-membered heterocycles. Metabolism of these groups can lead to chemically reactive electrophiles. Strategies that have been used to minimize the associated risk involve replacing the structural-alert moiety, blocking or making metabolism less favorable, and incorporating metabolic soft spots to facilitate metabolism away from the structural-alert substituent. The metabolism of drugs to radicals usually leads to cellular oxidative stress. The formation of radical metabolites can be minimized through the use of similar approaches but remains an area less frequently considered in drug design.
Orexin Receptors: Pharmacology and Therapeutic Opportunities
Authors: Scammell Thomas E. , Winrow Christopher J.
Published: January 2011

Orexin-A and -B (also known as hypocretin-1 and -2) are neuropeptides produced in the lateral hypothalamus that promote many aspects of arousal through the OX1 and OX2 receptors. In fact, they are necessary for normal wakefulness, as loss of the orexin-producing neurons causes narcolepsy in humans and rodents. This has generated considerable interest in developing small-molecule orexin receptor antagonists as a novel therapy for the treatment of insomnia. Orexin antagonists, especially those that block OX2 or both OX1 and OX2 receptors, clearly promote sleep in animals, and clinical results are encouraging: Several compounds are in Phase III trials. As the orexin system mainly promotes arousal, these new compounds will likely improve insomnia without incurring many of the side effects encountered with current medications.
Physiologically-Based Pharmacokinetics in Drug Development and Regulatory Science
Authors: Rowland Malcolm , Peck Carl , Tucker Geoffrey
Published: January 2011

The application of physiologically-based pharmacokinetic (PBPK) modeling is coming of age in drug development and regulation, reflecting significant advances over the past 10 years in the predictability of key pharmacokinetic (PK) parameters from human in vitro data and in the availability of dedicated software platforms and associated databases. Specific advances and contemporary challenges with respect to predicting the processes of drug clearance, distribution, and absorption are reviewed, together with the ability to anticipate the quantitative extent of PK-based drug-drug interactions and the impact of age, genetics, disease, and formulation. The value of this capability in selecting and designing appropriate clinical studies, its implications for resource-sparing techniques, and a more holistic view of the application of PK across the preclinical/clinical divide are considered. Finally, some attention is given to the positioning of PBPK within the drug development and approval paradigm and its future application in truly personalized medicine.
Strategies to Discover Unexpected Targets for Drugs Active at G Protein–Coupled Receptors
Authors: Allen John A. , Roth Bryan L.
Published: January 2011

G protein–coupled receptors (GPCRs) are an evolutionarily conserved family of signaling molecules comprising approximately 2% of the human genome; this receptor family remains a central focus in basic pharmacology studies and drug discovery efforts. Detailed studies of drug action at GPCRs over the past decade have revealed existing and novel ligands that exhibit polypharmacology—that is, drugs with activity at more than one receptor target for which they were designed. These “off-target” drug actions can be a liability that causes adverse side effects; however, in several cases, drugs with less selectivity demonstrate better clinical efficacy. Here we review physical screening and cheminformatic approaches that define drug activity at the GPCR receptorome. In many cases, such profiling has revealed unexpected targets that explain therapeutic actions as well as off-targets underlying drug side effects. Such drug-receptor profiling has also provided new insights into mechanisms of action of existing drugs and has suggested directions for future drug development.
Drugging the Cancer Stem Cell Compartment: Lessons Learned from the Hedgehog and Wnt Signal Transduction Pathways
Authors: Dodge Michael E. , Lum Lawrence
Published: January 2011

Cell-cell communication mediated by the secreted Hedgehog (Hh) and Wnt signaling molecules is essential to the coordination of cell fate decision making throughout the metazoan lifespan. From decades of genetically based interrogation, core components constituting the Hh and Wnt signal transduction pathways have been assembled, and a deep appreciation of how these signals elaborate distinct bodily tissues during development has been established. On the other hand, our incapacity to leverage similar genetic approaches to study adult organ systems has limited our understanding of how these molecules promote tissue renewal and regeneration through stem cell regulation. We discuss recent progress in the use of chemically based approaches to achieve control of these pathway activities in a broad range of biological studies and therapeutic contexts. In particular, we discuss the unique experimental opportunities that chemical modulators of these pathways afford in exploring the cancer stem cell hypothesis.
Transcriptional and Epigenetic Regulation of Opioid Receptor Genes: Present and Future
Authors: Wei Li-Na , Loh Horace H.
Published: January 2011

Three opioid receptors (ORs) are known: μ opioid receptors (MORs), δ opioid receptors (DORs), and κ opioid receptors (KORs). Each is encoded by a distinct gene, and the three OR genes share a highly conserved genomic structure and promoter features, including an absence of TATA boxes and sensitivity to extracellular stimuli and epigenetic regulation. However, each of the genes is differentially expressed. Transcriptional regulation engages both basal and regulated transcriptional machineries and employs activating and silencing mechanisms. In retinoic acid–induced neuronal differentiation, the opioid receptor genes undergo drastically different chromatin remodeling processes and display varied patterns of epigenetic marks. Regulation of KOR expression is distinctly complex, and KOR exerts a unique function in neurite extension, indicating that KOR is not simply a pharmacological cousin of MOR and DOR. As the expression of OR proteins is ultimately controlled by extensive posttranscriptional processing, the pharmacological implication of OR gene regulation at the transcriptional level remains to be determined.
Mechanisms of the Anti-Cancer and Anti-Inflammatory Actions of Vitamin D
Authors: Krishnan Aruna V. , Feldman David
Published: January 2011

Calcitriol, the hormonally active form of vitamin D, is being evaluated in clinical trials as an anti-cancer agent. Calcitriol exerts multiple anti-proliferative, pro-apoptotic, and pro-differentiating actions on various malignant cells and retards tumor growth in animal models of cancer. Calcitriol also exhibits several anti-inflammatory effects including suppression of prostaglandin (PG) action, inhibition of p38 stress kinase signaling, and the subsequent production of pro-inflammatory cytokines and inhibition of NF-κB signaling. Calcitriol also decreases the expression of aromatase, the enzyme that catalyzes estrogen synthesis in breast cancer, both by a direct transcriptional repression and indirectly by reducing PGs, which are major stimulators of aromatase transcription. Other important effects include the suppression of tumor angiogenesis, invasion, and metastasis. These calcitriol actions provide a basis for its potential use in cancer therapy and chemoprevention. We summarize the status of trials involving calcitriol and its analogs, used alone or in combination with known anti-cancer agents.
Macrophages and Tissue Injury: Agents of Defense or Destruction?
Authors: Laskin Debra L. , Sunil Vasanthi R. , Gardner Carol R. , Laskin Jeffrey D.
Published: January 2011

The past several years have seen the accumulation of evidence demonstrating that tissue injury induced by diverse toxicants is due not only to their direct effects on target tissues but also indirectly to the actions of resident and infiltrating macrophages. These cells release an array of mediators with cytotoxic, pro- and anti-inflammatory, angiogenic, fibrogenic, and mitogenic activity, which function to fight infections, limit tissue injury, and promote wound healing. However, following exposure to toxicants, macrophages can become hyperresponsive, resulting in uncontrolled or dysregulated release of mediators that exacerbate acute tissue injury and/or promote the development of chronic diseases such as fibrosis and cancer. Evidence suggests that the diverse activity of macrophages is mediated by distinct subpopulations that develop in response to signals within their microenvironment. Understanding the precise roles of these different macrophage populations in the pathogenic response to toxicants is key to designing effective treatments for minimizing tissue damage and chronic disease and for facilitating wound repair.
Schizophrenia: Treatment Targets Beyond Monoamine Systems
Authors: Ibrahim Hisham M. , Tamminga Carol A.
Published: January 2011

We develop the proposal in this review that schizophrenia is a syndrome made up of component symptom complexes, each with distinctive clinical correlates, pathophysiology, and selective treatments. Psychosis is the necessary component of the syndrome; it has a young-adult onset and is sensitive to current antipsychotic drugs. Cognitive dysfunction often precedes psychosis onset, does not present an episodic course, and is poorly responsive to antipsychotic drugs. Treatments for cognition are being developed largely on the basis of animal pharmacology. Drugs for component symptom complexes will theoretically be coadministered to independent symptomatic end points. Animal models, some with genetic characteristics, can be more easily and directly developed to match an individual component than to match an illness definition as broad as schizophrenia.
Changes in extracellular matrix composition regulate cyclooxygenase-2 expression in human mesangial cells
Authors: Alique Matilde , Calleros Laura , Luengo Alicia , Griera Mercedes , Iñiguez Miguel Ángel , Punzón Carmen , Fresno Manuel , Rodríguez-Puyol Manuel , Rodríguez-Puyol Diego
Published: January 2011

Glomerular diseases are characterized by a sustained synthesis and accumulation of abnormal extracellular matrix proteins, such as collagen type I. The extracellular matrix transmits information to cells through interactions with membrane components, which directly activate many intracellular signaling events. Moreover, accumulating evidence suggests that eicosanoids derived from cyclooxygenase (COX)-2 participate in a number of pathological processes in immune-mediated renal diseases, and it is known that protein kinase B (AKT) may act through different transcription factors in the regulation of the COX-2 promoter. The present results show that progressive accumulation of collagen I in the extracellular medium induces a significant increase of COX-2 expression in human mesangial cells, resulting in an enhancement in PGE2 production. COX-2 overexpression is due to increased COX-2 mRNA levels. The study of the mechanism implicated in COX-2 upregulation by collagen I showed focal adhesion kinase (FAK) activation. Furthermore, we observed that the activation of the phosphatidylinositol 3-kinase (PI3K)/AKT pathway by collagen I and collagen I-induced COX-2 overexpression was abolished by PI3K and AKT inhibitors. Additionally, we showed that the cAMP response element (CRE) transcription factor is implicated. Finally, we studied COX-2 expression in an animal model, NG-nitro-l-arginine methyl ester hypertensive rats. In renal tissue and vascular walls, COX-2 and collagen type I content were upregulated. In summary, our results provide evidence that collagen type I increases COX-2 expression via the FAK/PI3K/AKT/cAMP response element binding protein signaling pathway.
Mechanisms of TNF induction by heat-killed Staphylococcus aureus differ upon the origin of mononuclear phagocytes
Authors: Kapetanovic Ronan , Parlato Marianna , Fitting Catherine , Quesniaux Valérie , Cavaillon Jean-Marc , Adib-Conquy Minou
Published: January 2011

Mononuclear phagocytes are among the first immune cells activated after pathogens invasion. Although they all derive from the same progenitor in the bone marrow, their characteristics differ on the compartment from which they are derived. In this work, we investigated the contribution of phagocytosis for tumor necrosis factor (TNF) production by murine mononuclear phagocytes (monocytes, peritoneal and alveolar macrophages) in response to heat-killed Staphylococcus aureus (HKSA). Mononuclear phagocytes behaved differently, depending on their compartment of residence. Indeed, when bacterial uptake or phagosome maturation was blocked, activation through membrane receptors was sufficient for a maximal production of TNF and interleukin-10 by peritoneal macrophages. In contrast, monocytes, and to a lesser extent alveolar macrophages, required phagocytosis for optimal cytokine production. While investigating the different actors of signalization, we found that p38 kinase and phosphatidylinositol 3-kinase were playing an important role in HKSA phagocytosis and TNF production. Furthermore, blocking the α5β1-integrin significantly decreased TNF production in response to HKSA in all three cell types. Finally, using mononuclear phagocytes from NOD2 knockout mice, we observed that TNF production in response to HKSA was dependent on NOD2 for monocytes and peritoneal macrophages. In conclusion, we demonstrate that the mechanisms of activation leading to TNF production in response to HKSA are specific for each mononuclear phagocyte population and involve different recognition processes and signaling pathways. The influence of the compartments on cell properties and behavior should be taken into account, to better understand cell physiology and host-pathogen interaction, and to define efficient strategies to fight infection.
Akt directly regulates focal adhesion kinase through association and serine phosphorylation: implication for pressure-induced colon cancer metastasis
Authors: Wang Shouye , Basson Marc D.
Published: January 2011

Although focal adhesion kinase (FAK) is typically considered upstream of Akt, extracellular pressure stimulates cancer cell adhesion via Akt-dependent FAK activation. How Akt regulates FAK is unknown. We studied Akt-FAK interaction in colon cancer cells under 15 mmHg increased extracellular pressure. Pressure enhanced Akt-FAK association, blocked by inhibiting FAK or silencing Akt1 but not Akt2, and stimulated FAK serine phosphorylation in Caco-2 and human colon cancer cells from surgical specimens Akt1-dependently. FAK includes three serine (S517/601/695) and one threonine (T600)-containing consensus sequences for Akt phosphorylation. Studying S–>A nonphosphorylatable point mutants suggests that these sites coordinately upregulate FAK Y397 tyrosine phosphorylation, which conventionally initiates FAK activation, and mediate pressure-induced cancer cell adhesion. FAK(T600A) mutation did not prevent pressure-induced FAK(Y397) phosphorylation or adhesion. Akt1 appeared to directly bind FAK, and this binding did not depend on the FAK autophosphorylation site (Y397). In addition, our results demonstrated that Akt phosphorylated FAK at three novel serine phosphorylation sites, which were also not required for FAK-Akt binding. This novel interaction suggests that FAK and Akt may be dual kinase targets to prevent cancer cell adhesion and metastasis.
Physiology, structure, and susceptibility to injury of skeletal muscle in mice lacking keratin 19-based and desmin-based intermediate filaments
Authors: Lovering Richard M. , O'Neill Andrea , Muriel Joaquin M. , Prosser Benjamin L. , Strong John , Bloch Robert J.
Published: January 2011

Intermediate filaments, composed of desmin and of keratins, play important roles in linking contractile elements to each other and to the sarcolemma in striated muscle. Our previous results show that the tibialis anterior (TA) muscles of mice lacking keratin 19 (K19) lose costameres, accumulate mitochondria under the sarcolemma, and generate lower specific tension than controls. Here we compare the physiology and morphology of TA muscles of mice lacking K19 with muscles lacking desmin or both proteins [double knockout (DKO)]. K19−/− mice and DKO mice showed a threefold increase in the levels of creatine kinase (CK) in the serum. The absence of desmin caused a larger change in specific tension (−40%) than the absence of K19 (−19%) and played the predominant role in contractile function (−40%) and decreased tolerance to exercise in the DKO muscle. By contrast, the absence of both proteins was required to obtain a significantly greater loss of contractile torque after injury (−48%) compared with wild type (−39%), as well as near-complete disruption of costameres. The DKO muscle also showed a significantly greater misalignment of myofibrils than either mutant alone. In contrast, large subsarcolemmal gaps and extensive accumulation of mitochondria were only seen in K19-null TA muscles, and the absence of both K19 and desmin yielded milder phenotypes. Our results suggest that keratin filaments containing K19- and desmin-based intermediate filaments can play independent, complementary, or antagonistic roles in the physiology and morphology of fast-twitch skeletal muscle.
(−)-Epicatechin induces calcium and translocation independent eNOS activation in arterial endothelial cells
Authors: Ramirez-Sanchez Israel , Maya Lisandro , Ceballos Guillermo , Villarreal Francisco
Published: January 2011

The consumption of cacao-derived (i.e., cocoa) products provides beneficial cardiovascular effects in healthy subjects as well as individuals with endothelial dysfunction such as smokers, diabetics, and postmenopausal women. The vascular actions of cocoa are related to enhanced nitric oxide (NO) production. These actions can be reproduced by the administration of the cacao flavanol (−)-epicatechin (EPI). To further understand the mechanisms behind the vascular action of EPI, we investigated the effects of Ca2+ depletion on endothelial nitric oxide (NO) synthase (eNOS) activation/phosphorylation and translocation. Human coronary artery endothelial cells were treated with EPI or with bradykinin (BK), a well-known Ca2+-dependent eNOS activator. Results demonstrate that both EPI and BK induce increases in intracellular calcium and NO levels. However, under Ca2+-free conditions, EPI (but not BK) is still capable of inducing NO production through eNOS phosphorylation at serine 615, 633, and 1177. Interestingly, EPI-induced translocation of eNOS from the plasmalemma was abolished upon Ca2+ depletion. Thus, under Ca2+-free conditions, EPI can stimulate NO synthesis independent of calmodulin binding to eNOS and of its translocation into the cytoplasm. We also examined the effect of EPI on the NO/cGMP/vasodilator-stimulated phosphoprotein (VASP) pathway activation in isolated Ca2+-deprived canine mesenteric arteries. Results demonstrate that under these conditions, EPI induces the activation of this vasorelaxation-related pathway and that this effect is inhibited by pretreatment with nitro-l-arginine methyl ester, suggesting a functional relevance for this phenomenon.
Syntaxin 1A regulates surface expression of β-cell ATP-sensitive potassium channels
Authors: Chen Pei-Chun , Bruederle Cathrin E. , Gaisano Herbert Y. , Shyng Show-Ling
Published: January 2011

The pancreatic ATP-sensitive potassium (KATP) channel consisting of four inwardly rectifying potassium channel 6.2 (Kir6.2) and four sulfonylurea receptor SUR1 subunits plays a key role in insulin secretion by linking glucose metabolism to membrane excitability. Syntaxin 1A (Syn-1A) is a plasma membrane protein important for membrane fusion during exocytosis of insulin granules. Here, we show that Syn-1A and KATP channels endogenously expressed in the insulin-secreting cell INS-1 interact. Upregulation of Syn-1A by overexpression in INS-1 leads to a decrease, whereas downregulation of Syn-1A by small interfering RNA (siRNA) leads to an increase, in surface expression of KATP channels. Using COSm6 cells as a heterologous expression system for mechanistic investigation, we found that Syn-1A interacts with SUR1 but not Kir6.2. Furthermore, Syn-1A decreases surface expression of KATP channels via two mechanisms. One mechanism involves accelerated endocytosis of surface channels. The other involves decreased biogenesis and processing of channels in the early secretory pathway. This regulation is KATP channel specific as Syn-1A has no effect on another inward rectifier potassium channel Kir3.1/3.4. Our results demonstrate that in addition to a previously documented role in modulating KATP channel gating, Syn-1A also regulates KATP channel expression in β-cells. We propose that physiological or pathological changes in Syn-1A expression may modulate insulin secretion by altering glucose-secretion coupling via changes in KATP channel expression.
A practical guide to evaluating colocalization in biological microscopy
Authors: Dunn Kenneth W. , Kamocka Malgorzata M. , McDonald John H.
Published: January 2011

Fluorescence microscopy is one of the most powerful tools for elucidating the cellular functions of proteins and other molecules. In many cases, the function of a molecule can be inferred from its association with specific intracellular compartments or molecular complexes, which is typically determined by comparing the distribution of a fluorescently labeled version of the molecule with that of a second, complementarily labeled probe. Although arguably the most common application of fluorescence microscopy in biomedical research, studies evaluating the “colocalization” of two probes are seldom quantified, despite a diversity of image analysis tools that have been specifically developed for that purpose. Here we provide a guide to analyzing colocalization in cell biology studies, emphasizing practical application of quantitative tools that are now widely available in commercial and free image analysis software.
Synthetic and natural polyanions induce cytochrome c release from mitochondria in vitro and in situ
Authors: Krasnikov Boris F. , Melik-Nubarov Nickolay S. , Zorova Lubava D. , Kuzminova Alevtina E. , Isaev Nickolay K. , Cooper Arthur J. L. , Zorov Dmitry B.
Published: January 2011

A synthetic polyanion composed of styrene, maleic anhydride, and methacrylic acid (molar ratio 56:37:7) significantly inhibited the respiration of isolated rat liver mitochondria in a time-dependent fashion that correlated with 1) collapse of the mitochondrial membrane potential and 2) high amplitude mitochondrial swelling. The process is apparently Ca2+ dependent. Since it is blocked by cyclosporin A, the process is ascribed to induction of the mitochondrial permeability transition. In mitoplasts, i.e., mitochondria lacking their outer membranes, the polyanion rapidly blocked respiration. After incubation of rat liver mitochondria with the polyanion, cytochrome c was released into the incubation medium. In solution, the polyanion modified by conjugation with fluorescein formed a complex with cytochrome c. Addition of the polyanion to cytochrome c-loaded phosphatidylcholine/cardiolipin liposomes induced the release of the protein from liposomal membrane evidently due to coordinated interplay of Coulomb and hydrophobic interactions of the polymer with cytochrome c. We conclude that binding of the polyanion to cytochrome c renders it inactive in the respiratory chain due to exclusion from its native binding sites. Apparently, the polyanion interacts with cytochrome c in mitochondria and releases it to the medium through breakage of the outer membrane as a result of severe swelling. Similar properties were demonstrated for the natural polyanion, tobacco mosaic virus RNA. An electron microscopy study confirmed that both polyanions caused mitochondrial swelling. Exposure of cerebellar astroglial cells in culture to the synthetic polyanion resulted in cell death, which was associated with nuclear fragmentation.
TonEBP stimulates multiple cellular pathways for adaptation to hypertonic stress: organic osmolyte-dependent and -independent pathways
Authors: Lee Sang Do , Choi Soo Youn , Lim Sun Woo , Lamitina S. Todd , Ho Steffan N. , Go William Y. , Kwon H. Moo
Published: January 2011

TonEBP (tonicity-responsive enhancer binding protein) is a transcription factor that promotes cellular accumulation of organic osmolytes in the hypertonic renal medulla by stimulating expression of its target genes. Genetically modified animals with deficient TonEBP activity in the kidney suffer from severe medullary atrophy in association with cell death, demonstrating that TonEBP is essential for the survival of the renal medullary cells. Using both TonEBP knockout cells and RNA interference of TonEBP, we found that TonEBP promoted cellular adaptation to hypertonic stress. Microarray analyses revealed that the genetic response to hypertonicity was dominated by TonEBP in that expression of totally different sets of genes was increased by hypertonicity in those cells with TonEBP vs. those without TonEBP activity. Of over 100 potentially new TonEBP-regulated genes, we selected seven for further analyses and found that their expressions were all dependent on TonEBP. RNA interference experiments showed that some of these genes, asporin, insulin-like growth factor-binding protein-5 and -7, and an extracellular lysophospholipase D, plus heat shock protein 70, a known TonEBP target gene, contributed to the adaptation to hypertonicity without promoting organic osmolyte accumulation. We conclude that TonEBP stimulates multiple cellular pathways for adaptation to hypertonic stress in addition to organic osmolyte accumulation.
Counteracting vasopressin-mediated water reabsorption by ATP, dopamine, and phorbol esters: mechanisms of action
Authors: Boone Michelle , Kortenoeven Marleen L. A. , Robben Joris H. , Tamma Grazia , Deen Peter M. T.
Published: January 2011

Water homeostasis is regulated by a wide variety of hormones. When in need for water conservation, vasopressin, released from the brain, binds renal principal cells and initiates a signaling cascade resulting in the insertion of aquaporin-2 (AQP2) water channels in the apical membrane and water reabsorption. Conversely, hormones, including extracellular purines and dopamine, antagonize AVP-induced water permeability, but their mechanism of action is largely unknown, which was investigated here. Addition of these hormones to mpkCCD cells decreased total and plasma membrane abundance of AVP-induced AQP2, partly by increasing its internalization to vesicles and lysosomal degradation. This internalization was ubiquitin dependent, because the hormones increased AQP2 ubiquitination, and the plasma membrane localization of AQP2-K270R, which cannot be monoubiquitinated, was unaffected by these hormones. Both hormones also increased AQP2 phosphorylation at S261, which followed ubiquitination, but was not essential for hormone-induced AQP2 degradation. A similar process occurs in vivo, as incubation of dDAVP-treated kidney slices with both hormones also resulted in the internalization and S261 phosphorylation of AQP2. Both hormones also reduced cAMP and AQP2 mRNA levels, suggesting an additional effect on AQP2 gene transcription. Interestingly, phorbol esters only reduced AQP2 through the first pathway. Together, our results indicate that ATP and dopamine counteract AVP-induced water permeability by increasing AQP2 degradation in lysosomes, preceded by ubiquitin-dependent internalization, and by decreasing AQP2 gene transcription by reducing the AVP-induced cAMP levels.
Reciprocal changes in renal ACE/ANG II and ACE2/ANG 1–7 are associated with enhanced collecting duct renin in Goldblatt hypertensive rats
Authors: Prieto Minolfa C. , González-Villalobos Romer A. , Botros Fady T. , Martin Victoria L. , Pagán Javier , Satou Ryousuke , Lara Lucienne S. , Feng Yumei , Fernandes Fernanda B. , Kobori Hiroyuki , Casarini Dulce E. , Navar L. Gabriel
Published: January 2011

Alterations in the balance between ANG II/ACE and ANG 1–7/ACE2 in ANG II-dependent hypertension could reduce the generation of ANG 1–7 and contribute further to increased intrarenal ANG II. Upregulation of collecting duct (CD) renin may lead to increased ANG II formation during ANG II-dependent hypertension, thus contributing to this imbalance. We measured ANG I, ANG II, and ANG 1–7 contents, angiotensin-converting enzyme (ACE) and ACE2 gene expression, and renin activity in the renal cortex and medulla in the clipped kidneys (CK) and nonclipped kidneys (NCK) of 2K1C rats. After 3 wk of unilateral renal clipping, systolic blood pressure and plasma renin activity increased in 2K1C rats ( n = 11) compared with sham rats ( n = 9). Renal medullary angiotensin peptide levels were increased in 2K1C rats [ANG I: (CK = 171 ± 4; NCK = 251 ± 8 vs. sham = 55 ± 3 pg/g protein; P < 0.05); ANG II: (CK = 558 ± 79; NCK = 328 ± 18 vs. sham = 94 ± 7 pg/g protein; P < 0.001)]; and ANG 1–7 levels decreased (CK = 18 ± 2; NCK = 19 ± 2 pg/g vs. sham = 63 ± 10 pg/g; P < 0.001). In renal medullas of both kidneys of 2K1C rats, ACE mRNA levels and activity increased but ACE2 decreased. In further studies, we compared renal ACE and ACE2 mRNA levels and their activities from chronic ANG II-infused ( n = 6) and sham-operated rats ( n = 5). Although the ACE mRNA levels did not differ between ANG II rats and sham rats, the ANG II rats exhibited greater ACE activity and reduced ACE2 mRNA levels and activity. Renal medullary renin activity was similar in the CK and NCK of 2K1C rats but higher compared with sham. Thus, the differential regulation of ACE and ACE2 along with the upregulation of CD renin in both the CK and NCK in 2K1C hypertensive rats indicates that they are independent of perfusion pressure and contribute to the altered content of intrarenal ANG II and ANG 1–7.