bluuebunny/crossref_metadata_2025 huggingface dataset:
Simultaneous Determination of Regional Cerebral Blood Flow and Blood—Brain Glucose Transport Kinetics in the Gerbil
Authors: Betz A. Lorris , Iannotti Fausto
Published: April 2011

Cerebral blood flow (CBF) and unidirectional transport of glucose from blood to brain were measured simultaneously in four brain regions of the pentobarbital-anesthetized gerbil. The method consisted of the intravenous injection of a bolus containing [14C]butanol and [3H]glucose, followed by continuous withdrawal of arterial blood and sampling of brain 25 s later. CBF was lowest in the cerebral cortex (50 ml 100 g−1 min−1), highest in the brainstem (89 ml 100 g−1 min−1), and intermediate in the basal ganglia and cerebellum (66 and 69 ml 100 g−1 min−1, respectively). The kinetics of blood-to-brain glucose transport were measured in animals whose blood glucose concentration had been altered by glucose or insulin injections. The half-saturation constant for glucose transport ( Km) was similar in all brain regions (7.37–8.14 m M), while the maximal rate of transport ( Vmax) was lowest in the cerebral cortex (1.55 μmol g−1 min−1) and significantly higher in the basal ganglia, cerebellum, and brainstem (1.81–2.02 μmol g−1 min−1). These values for CBF and glucose transport are similar to those reported in the literature for other pentobarbital-anesthetized animals. The method provides a simple and rapid technique for determining the effect of ischemia and alterations in CBF on blood-to-brain glucose transport.
Responses of Isolated Feline and Human Cerebral Arteries to Prostacyclin and Some of its Metabolites
Authors: Uski Tore , Andersson Karl-Erik , Brandt Lennart , Edvinsson Lars , Ljunggren Bengt
Published: April 2011

The effects of prostacyclin (PGI2) were studied in isolated cat basilar and middle cerebral arteries and in human pial arteries. In feline vessels with low resting tension, PGI2 had a contractile effect that reached a maximum of 132% (basilar artery) and 23% (middle cerebral artery) of the potassium-induced (127 m M) contraction. In potassium-contracted feline vessels, PGI2 caused a further contraction. When these vessels were contracted by PGF2α, PGI2 induced relaxation, which was most marked in the middle cerebral artery. PGI2 consistently relaxed the middle cerebral artery contracted by the prostaglandin endoperoxide analogue U-44069, whereas the basilar artery was almost unaffected. In human pial arteries with low resting tension, PGI2 had no effects in concentrations below 10−6 M, whereas higher concentrations induced contractions. In potassium-contracted (35 or 127 m M) preparations, PGI2 in concentrations below 10−6 M produced relaxation; in higher concentrations further contraction was induced. Human pial arteries contracted by PGF2α, U-44069, noradrenaline, or 5-hydroxytryptamine consistently relaxed in response to PGI2 (< 10−6 M). The PGI2 metabolite 6-keto-PGE1 had effects similar to those of PGI2, but proved to be less potent on human pial vessels. 6-Keto-PGF1α was ineffective, whereas 6, 15-diketo-PGF1α had minor relaxant effects. The results suggest that consideration must be given to regional as well as species differences concerning the cerebrovascular effects of PGI2.
Effects of Midazolam on Cerebral Hemodynamics and Cerebral Vasomotor Responsiveness to Carbon Dioxide
Authors: Forster A. , Juge O. , Morel D.
Published: April 2011

Although it is known that hypercarbia increases and benzodiazepines decrease cerebral blood flow (CBF), the effects of benzodiazepines on CBF responsiveness to CO2 are not well documented. The influence on CBF and CBF-C02 sensitivity of placebo or midazolam, which is a new water-soluble benzodiazepine, was measured in eight healthy volunteers using the noninvasive 133Xe inhalation method for CBF determination. Under normocarbia, midazolam decreased CBF from 40.6 ± 3.2 to 27.0 ± 5.0 ml 100 g−1 min−1 (x̄ ± SD). At a later session under hypercarbia, CBF was 58.8 ± 4.4 ml 100 g−1 min−1 after administration of placebo, and 49.1 ± 10.2 ml 100 g−1 min−1 after midazolam. The mean of the slopes correlating Paco2 and CBF was significantly steeper with midazolam (2.5 ± 1.2 ml 100 g−1 min−1 mm Hg−1) than with placebo (1.5 ± 0.4 ml 100 g−1 min−1 mm Hg−1). Our results suggest that midazolam may be a safe agent to use in patients with intracranial hypertension, since it decreases CBF and thus cerebral blood volume; however, it should be administered with caution in nonventilated patients with increased intracranial pressure, since its beneficial effects on cerebrovascular tone can be readily counteracted by the increase in arterial CO2 tension induced by this drug.
Estimation of Local Cerebral Protein Synthesis Rates with L-[1-11C]Leucine and PET: Methods, Model, and Results in Animals and Humans
Authors: Hawkins Randall A. , Huang Sung-Cheng , Barrio Jorge R. , Keen Randy E. , Feng Dagan , Mazziotta John C. , Phelps Michael E.
Published: April 2011

We have estimated the cerebral protein synthesis rates (CPSR) in a series of normal human volunteers and monkeys using l-[1-11C]leucine and positron emission tomography (PET) using a three-compartment model. The model structure, consisting of a tissue precursor, metabolite, and protein compartment, was validated with biochemical assay data obtained in rat studies. The CPSR values estimated in human hemispheres of about 0.5 nmol/min/g agree well with hemispheric estimates in monkeys. The sampling requirements (input function and scanning sequence) for accurate estimates of model parameters were investigated in a series of computer simulation studies.
The C15O2 Build-up Technique to Measure Regional Cerebral Blood Flow and Volume of Distribution of Water
Authors: Lammertsma Adriaan A. , Frackowiak Richard S. J. , Hoffman John M. , Huang Sung-Cheng , Weinberg Irving N. , Dahlbom Magnus , MacDonald Norman S. , Hoffman Edward J. , Mazziotta John C. , Heather Jon D. , Forse Gerry R. , Phelps Michael E. , Jones Terry
Published: April 2011

A new method to measure regional CBF (rCBF) and volume of distribution of water is presented. It centres on recording the tissue build-up and retention of 15O-labelled water during the continuous inhalation of 15O-labelled carbon dioxide. Simultaneously, the arterial concentration is continuously monitored, and corrections for delay and dispersion in the recorded response are made by curve fitting. The values for the volume of distribution of water obtained in four normal subjects were close to reported in vitro values. Using the same fixed distribution volumes for both build-up and steady-state studies resulted in comparable rCBF values for both techniques.
The Effects of Naloxone on Cerebral Blood Flow and Cerebral Function during Relative Cerebral Ischemia
Authors: Skarphedinsson Jon Olafur , Delle Martin , Hoffman Pavel , Thorén Peter
Published: April 2011

CBF and somatosensory evoked potentials (SEPs) were measured in a model of moderate cerebral ischemia in anesthetized spontaneously hypertensive rats. The rats were bled to reduce SEP amplitudes to about 50% of prebleeding control. The consequent blood pressure fall reduced CBF to 77% of control as measured by the laser-Doppler technique. Naloxone (5 mg kg−1 i.v. plus 25 mg kg−1 h−1 i.v. for 30 min) caused a significant increase in SEP amplitudes, while CBF did not change significantly. In addition, the latency of the first SEP component decreased toward prebleeding values. Heart rate (HR) decreased, but MABP was held constant by a pressure-regulating reservoir. In unbled rats, naloxone (5 mg kg−1 i.v.) caused a transient small increase in MABP and SEP amplitudes and decrease in HR. These results indicate that sensory input is regulated by opioid systems. Increased opioid activity may inhibit ascending sensory pathways during relative cerebral ischemia and thereby depress SEP responses. Thus, naloxone can release this inhibition and enhances SEP independently of CBF during relative cerebral ischemia. Similar mechanisms might explain the apparently beneficial effects of naloxone in some stroke models.
The Effect of Local Infusion of Adenosine and Adenosine Analogues on Local Cerebral Blood Flow
Authors: Van Wylen David G. L. , Park T. S. , Rubio Rafael , Berne Robert M.
Published: April 2011

The purpose of this study was to determine the effects of local infusion of adenosine (ADO) and non-metabolized ADO analogues on local cerebral blood flow (CBF) and interstitial fluid (ISF) ADO levels. The brain dialysis technique was used to (a) deliver drugs locally to brain tissue, (b) estimate cerebral ISF ADO levels, and (c) measure local CBF (hydrogen clearance). Dialysis probes were implanted bilaterally in the caudate nuclei of ketamine-anesthetized rats. The probe on one side was perfused with artificial CSF while the contralateral probe was perfused with artificial CSF containing ADO ( n = 5), or the ADO agonists 2-chloroadenosine (2-CADO; n = 4) or 5'-N-ethylcarboxamide adenosine (NECA; n = 4). When ADO was included in the artificial CSF at 10−5, 10−4, or 10−3 M, a 30% increase in local CBF was detected only with 10−3 M ADO. During perfusion with ADO, dialysate inosine and hypoxanthine levels increased, indicating that the cells adjacent to the probe metabolized the exogenous ADO. With 2-CADO included in the artificial CSF at 10−6, 10−5, or 10−4 M, local CBF increased 18, 131, and 201%, respectively. Perfusion with artificial CSF containing 10−7, 10−6, or 10−5 M NECA resulted in a 35, 112, and 187% increase in local CBF, respectively. In a separate group of rats ( n = 6), perfusion with artificial CSF containing 10−6 M NECA resulted in a sustained twofold increase in local CBF and 40% decrease in dialysate adenosine concentration, both of which could be reversed by including 8-( p-sulfophenyl)-theophylline, an ADO receptor antagonist, in the artificial CSF. These results are consistent with the known vascular actions of ADO and ADO analogues and suggest that there is a basal level of ISF ADO that can be reduced by increased CBF and/or adenosine receptor activation.
Histochemical Representation of Regional ATP in the Brain Using a Firefly Luciferase—Immobilized Membrane in a Multilayer Film Format
Authors: Kobayashi Shuichi , Kikuchi Haruhiko , Ishikawa Masatsune , Kinuta Yuji , Hashimoto Kenji
Published: April 2011

The enzymatic bioluminescence of firefly luciferase has been used in sensitive pictorial assays of ATP. We describe a method using a membrane with immobilized luciferase in a multilayer film format for the histochemical representation of brain ATP content. The multilayer film consisted of a transparent support, a reagent layer, and a pigment layer. The reagent layer contained all necessary reagents, including immobilized luciferase. The pigment layer was effective for high image resolution. An unfixed slice of frozen brain 16 μm thick was placed on the film. The chemical energy of brain ATP was converted into luminescent energy in the reagent layer and the bioluminescence emitted was recorded photographically with high spatial resolution. A close linear relationship was obtained between the optical density of the bioluminescent images and logarithmic plots of the brain ATP content. With this film, the regional ATP content in fine anatomical structures of gerbil brains was clearly demonstrated in both physiological and pathological states.
Greater Weight Loss and Hormonal Changes After 6 Months Diet With Carbohydrates Eaten Mostly at Dinner
Authors: Sofer Sigal , Eliraz Abraham , Kaplan Sara , Voet Hillary , Fink Gershon , Kima Tzadok , Madar Zecharia
Published: April 2011

This study was designed to investigate the effect of a low‐calorie diet with carbohydrates eaten mostly at dinner on anthropometric, hunger/satiety, biochemical, and inflammatory parameters. Hormonal secretions were also evaluated. Seventy‐eight police officers (BMI >30) were randomly assigned to experimental (carbohydrates eaten mostly at dinner) or control weight loss diets for 6 months. On day 0, 7, 90, and 180 blood samples and hunger scores were collected every 4 h from 0800 to 2000 hours. Anthropometric measurements were collected throughout the study. Greater weight loss, abdominal circumference, and body fat mass reductions were observed in the experimental diet in comparison to controls. Hunger scores were lower and greater improvements in fasting glucose, average daily insulin concentrations, and homeostasis model assessment for insulin resistance (HOMAIR), T‐cholesterol, low‐density lipoprotein (LDL) cholesterol, high‐density lipoprotein (HDL) cholesterol, C‐reactive protein (CRP), tumor necrosis factor‐α (TNF‐α), and interleukin‐6 (IL‐6) levels were observed in comparison to controls. The experimental diet modified daily leptin and adiponectin concentrations compared to those observed at baseline and to a control diet. A simple dietary manipulation of carbohydrate distribution appears to have additional benefits when compared to a conventional weight loss diet in individuals suffering from obesity. It might also be beneficial for individuals suffering from insulin resistance and the metabolic syndrome. Further research is required to confirm and clarify the mechanisms by which this relatively simple diet approach enhances satiety, leads to better anthropometric outcomes, and achieves improved metabolic response, compared to a more conventional dietary approach.
Reduction of 8‐iso‐Prostaglandin F2α in the First Week After Roux‐en‐Y Gastric Bypass Surgery
Authors: Ueda Yukiko , Hajri Tahar , Peng DunFa , Marks‐Shulman Pamela A. , Tamboli Robyn A. , Shukrallah Bassam , Saliba Jabbar , Jabbour Kareem , El‐Rifai Wael , Abumrad Nada A. , Abumrad Naji N.
Published: April 2011

Obesity is associated with increased markers of oxidative stress. We examined whether oxidative stress is reduced within the first week after Roux‐en‐Y gastric bypass (RYGB) surgery and could be related to changes in adipose tissue depots. The reactive oxygen species (ROS) marker 8‐iso‐prostaglandin F2α (8‐iso‐PGF2α) and activity of antioxidant glutathione peroxidases (GPX) in plasma were compared before and ∼1 week after RYGB. The effects of RYGB on subcutaneous adipose tissue and interstitial fluid 8‐iso‐PGF2α levels and subcutaneous adipose tissue expression of GPX‐3 were also assessed. Levels of 8‐iso‐PGF2α in subcutaneous and visceral adipose tissue were determined. Plasma 8‐iso‐PGF2α levels decreased (122 ± 75 to 56 ± 15 pg/ml, P = 0.001) and GPX activity increased (84 ± 18 to 108 ± 25 nmol/min/ml, P = 0.003) in the first week post‐RYGB. RYGB also resulted in reductions of 8‐iso‐PGF2α in subcutaneous adipose tissue (1,742 ± 931 to 1,132 ± 420 pg/g fat, P = 0.046) and interstitial fluid (348 ± 118 to 221 ± 83 pg/ml, P = 0.046) that were comparable to plasma (26–33%, P = 0.74). Adipose GPX‐3 expression was increased (6.7 ± 4.7‐fold, P = 0.004) in the first postoperative week. The improvements in oxidative stress occurred with minimal weight loss (2.4 ± 3.4%, P = 0.031) and elevations in plasma interleukin‐6 (18.0 ± 46.8 to 28.0 ± 58.9 pg/ml, P = 0.004). Subcutaneous and visceral adipose tissues express comparable 8‐iso‐PGF2α levels (1,204 ± 470 and 1,331 ± 264 pg/g fat, respectively; P = 0.34). These data suggest that RYGB affects adipose tissue leading to the restoration of adipose redox balance within the first postoperative week and that plasma 8‐iso‐PGF2α is primarily derived from subcutaneous adipose tissue.
A high-performing nanostructured TiO2 filter for volatile organic compounds using atomic layer deposition
Authors: Lee Hye Jin , Seo Hyun Ook , Kim Dong Wun , Kim Kwang-Dae , Luo Yuan , Lim Dong Chan , Ju HyungKuk , Kim Jin Won , Lee Jaeyoung , Kim Young Dok
Published: April 2011

Atomic layer deposition of TiO2 on AAO produces a highly efficient toluene filter.
Anion-dependent fluorescence in bis(anilinoethynyl)pyridine derivatives: switchable ON–OFF and OFF–ON responses
Authors: Carroll Calden N. , Coombs Brian A. , McClintock Sean P. , Johnson II Charles A. , Berryman Orion B. , Johnson Darren W. , Haley Michael M.
Published: April 2011

Urea and sulfonamide derivatives of an arylacetylene scaffold exhibit ON–OFF and OFF–ON switchable colorimetric and fluorescent responses upon protonation.
The Role of the Geographical Imagination in Young People's Political Engagement
Authors: Hung Yvonne
Published: April 2011

This paper provides new insights into the ways in which urban youth draw upon and reference spatial concepts over the course of their participation in activism and organizing. The concept of the geographical imagination is the starting point from which to explore how young people's understanding of places near and far affects their political engagement. Civic participation is often conceived as voting and volunteering; however, this research suggests that young people who are collectively engaged in helping their community while extending their capacity to connect social forces to material outcomes are also civic and political actors. Furthermore, this paper shows how young people's experiences, perception, and attachment to different places inform the strategies and stances of their social and political activities. Drawing from a year-long investigation at a Harlem-based youth organization, the findings document how young people trace patterns of marginalization, neglect, and belonging in places near and far, which is an underexplored aspect of critical geography and youth participation. By showing how spatial concepts are embedded in young people's experiences with and narratives about their community's most pressing issues, an extended geographical imagination can help youth illuminate social and spatial injustice, and imagine progressive alternatives for change.
New York Encounters: Religion, Sexuality, and the City
Authors: Andersson Johan , Vanderbeck Robert M , Valentine Gill , Ward Kevin , Sadgrove Joanna
Published: April 2011

This paper explores questions of sexual difference and religious belief in relation to recent debates in urban studies and geography on urban encounters. Although it has been widely suggested that increased contact between members of different groups is an important driver for tolerant and respectful intergroup relations, there is need for more careful consideration of the kinds of sites that actually facilitate ‘meaningful encounters’. Specifically, we draw on empirical research in Episcopalian churches in New York City and examine how straight-identified parishioners and clergy narrate and perceive their encounters with the city's LGBT (lesbian, gay, bisexual, and transgender) population. Moving beyond the traditional focus on public space in the literature on cosmopolitan urbanism, we examine how churches serve as ‘micropublics’ which organize, facilitate, and/or limit encounters with sexual difference. To capture the tension between orthodox theological understandings of human sexuality and lived experiences in a metropolitan context where homosexuality is expressed relatively openly, the discussion focuses in particular on an evangelical case-study parish, where the church leadership is opposed to full LGBT inclusion in the church.
Passing Propinquities in the Multicultural City: The Everyday Encounters of Bus Passengering
Authors: Wilson Helen F
Published: April 2011

This paper examines how intercultural relations are continuously developed, destroyed, and remade in the practice of everyday bus travel. Through an ethnographic study of one bus route across Birmingham, UK, the paper explores the formation of relational practices on the move and the bodily orientations, public codes of conduct, material cultures, habits and affects through which they are formed. In particular, this paper gives specific attention to the tacit obligations of public travel and how such obligations both produce and sustain tolerance of others across a journey, to further reveal the multifaceted nature and workings of multicultural intimacies on the ground. In so doing, the paper responds to recent calls to politically revalorise public mobility spaces as key sites of encounter and identity formation, to position the bus as a crucial site of everyday multiculture through which wider processes of differentiation and exclusion are experienced and further understood.
Crime Management and Urban Governance: Everyday Interconnections in South Africa
Authors: Meth Paula
Published: April 2011

Interconnections between crime prevention and local governance practices are increasingly evident through the involvement of local partnerships and local government in crime prevention. The microlocal workings and the political implications of these interconnections have, however, received far less attention. This paper uses a case study from South Africa to understand the microlocal experiences of the interconnections between what is described here as ‘crime management’ and local governance. It is argued that the extent of interconnection is beyond that captured by the concept of ‘partnership’, as multiple governance structures, including local political parties, engage in crime management. Furthermore, the paper illustrates how local governance is dominated by crime management and that this domination is explicitly tied to the party political ‘ambitions’ of the dominant ANC party. The interconnection is theorised as the criminalisation of governance within a context of state-building.
Poverty and Place in Britain, 1968–99
Authors: Fahmy Eldin , Gordon David , Dorling Danny , Rigby Janette , Wheeler Ben
Published: April 2011

To date, analyses of long-term trends in the spatial distribution of poverty in Britain have been frustrated by a lack of consistency in definitions, data sources and measures, as well as by changes over time in census and administrative geographies. This paper draws upon a series of national poverty surveys in order to derive methodologically consistent estimates of breadline and core poverty. These models are then applied to census data in order to describe the changing geography of poverty in Britain over the 1968–99 period. The primary concern is to reveal the changing spatial distribution of poverty that lies behind the headline figures. These analyses suggest that not only has poverty become increasingly prevalent amongst British households, it also became increasingly spatially concentrated between 1968 and 1999.
Dynamically committed, uncommitted, and quenched states encoded in protein kinase A revealed by NMR spectroscopy
Authors: Masterson Larry R. , Shi Lei , Metcalfe Emily , Gao Jiali , Taylor Susan S. , Veglia Gianluigi
Published: April 2011

Protein kinase A (PKA) is a ubiquitous phosphoryl transferase that mediates hundreds of cell signaling events. During turnover, its catalytic subunit (PKA-C) interconverts between three major conformational states (open, intermediate, and closed) that are dynamically and allosterically activated by nucleotide binding. We show that the structural transitions between these conformational states are minimal and allosteric dynamics encode the motions from one state to the next. NMR and molecular dynamics simulations define the energy landscape of PKA-C, with the substrate allowing the enzyme to adopt a broad distribution of conformations (dynamically committed state) and the inhibitors (high magnesium and pseudosubstrate) locking it into discrete minima (dynamically quenched state), thereby reducing the motions that allow turnover. These results unveil the role of internal dynamics in both kinase function and regulation.
Gender and Politics in the Henrician Court: The Douglas-Howard Lyrics in the Devonshire Manuscript (BL Add 17492)*
Authors: Irish Bradley J.
Published: April 2011

BL Additional MS 17492, the so-called Devonshire Manuscript of Henrician courtly verse, is a prime example of how social and cultural phenomena contributed to early modern manuscript culture. Among the treasures of the Devonshire MS is a series of lyrics that chronicles a fascinating courtly intrigue of the 1530s: the illicit, clandestine marriage of Lord Thomas Howard and Lady Margaret Douglas, the headstrong niece of Henry VIII. After unpacking this historical drama, this essay advances the first substantial literary analysis of these poems by exploring the textual strategies through which Howard and Douglas attempted to negotiate the crown's insistent management of their erotic life. This treatment of the Douglas-Howard lyrics provides new opportunity to consider how the Devonshire MS reflects and refracts the gender dynamics of the contemporary Henrician court.
Nothing But the Truth? Hermeneutics and Morality in the Doctrines of Equivocation and Mental Reservation in Early Modern Europe
Authors: Tutino Stefania
Published: April 2011

This article examines certain aspects of the history of the doctrines of equivocation and mental reservation in early modern Catholic elaborations. It argues that the first Catholic theologians who engaged systematically with these doctrines, Domingo de Soto and Martin de Azpilcueta (Navarrus), used them as tools to investigate the potentialities and limitations of human language as a means to communicate meaning between a speaker and a listener. This article also shows that between the end of the sixteenth and the beginning of the seventeenth centuries Catholic theologians, both Jesuit and non-Jesuit, changed the debate over these doctrines into a debate over the moral quality of the speaker's intention. By analyzing the developments of the Catholic debate over equivocation and mental reservation, this article seeks to offer a fresh interpretation of the links between theology, morality, and hermeneutics.
Effect of lubricant molecular rheology on formation and shear of ultra-thin surface films
Authors: Chong W W F , Teodorescu M , Rahnejat H
Published: April 2011

The physics of molecularly thin fluid films formed between surface features at close range is investigated. It is found that the interplay between discrete lubricant drainage from such contacts and localized contact deflection plays an important role both on the load carrying capacity of these asperity level conjunctions as well as on friction. Small spherical molecules tend to solvate near assumed smooth surfaces of asperities at nano-scale. Their discrete drainage at steadily decreasing gaps adds to the viscous friction of any bulk lubricant film. However, at the same time the generated solvation pressures increase the load carrying capacity. Conversely, long chain molecules tend to inhibit solvation, thus showing a decrease in the load carrying capacity, whilst through their wetting action reduce friction. Consequently, real lubricants should comprise molecular species which promote desired contact characteristics, as indeed is the case for most base lubricants with surmised properties of certain additives. The methodology presented underpins the rather empirical implied action of surface adhered films. This is an initial approach which must be expanded to fluids with a more complex mix of species. If applicable, this could also be an alternative (potentially time saving) approach to Monte Carlo simulations for molecular dynamics.
Modeling electroluminescence in insulating polymers under ac stress: effect of excitation waveform
Authors: Baudoin F , Mills D H , Lewin P L , Le Roy S , Teyssedre G , Laurent C
Published: April 2011

A charge transport model allowing the description of electroluminescence in polyethylene films under ac stress is proposed. The fluid model incorporates bipolar charge injection/extraction, transport and recombination. The physics is based on hopping mobility of electronic carriers between traps with an exponential distribution in which trap filling controls the mobility. The computation mesh is very tight close to the electrodes, of the order of 0.4 nm, allowing mapping of the density of positive and negative carriers during sinusoidal, triangular and square 50 Hz voltage waveforms. Experiment and simulation fit nicely and the time dependence of the electroluminescence intensity is accounted for by the charge behaviour. Light emission scales with the injection current. It is shown that space charge affects a layer 10 nm away from the electrode where the mobility is increased as compared with the bulk mobility due to the high density of charge. The approach is very encouraging and opens the way to model space charge under time-varying voltages.
High doses of TGF-β potently suppress type I collagen via the transcription factorCUX1
Authors: Fragiadaki Maria , Ikeda Tetsurou , Witherden Abigail , Mason Roger M , Abraham David , Bou-Gharios George
Published: April 2011

Transforming growth factor-β (TGF-β) is an inducer of type I collagen, and uncontrolled collagen production leads to tissue scarring and organ failure. Here we hypothesize that uncovering a molecular mechanism that enables us to switch off type I collagen may prove beneficial in treating fibrosis. For the first time, to our knowledge, we provide evidence that CUX1 acts as a negative regulator of TGF-β and potent inhibitor of type I collagen transcription. We show that CUX1, a CCAAT displacement protein, is associated with reduced expression of type I collagen both in vivo and in vitro. We show that enhancing the expression of CUX1 results in effective suppression of type I collagen. We demonstrate that the mechanism by which CUX1 suppresses type I collagen is through interfering with gene transcription. In addition, using an in vivo murine model of aristolochic acid (AA)-induced interstitial fibrosis and human AA nephropathy, we observe that CUX1 expression was significantly reduced in fibrotic tissue when compared to control samples. Moreover, silencing of CUX1 in fibroblasts from kidneys of patients with renal fibrosis resulted in increased type I collagen expression. Furthermore, the abnormal CUX1 expression was restored by addition of TGF-β via the p38 mitogen-activated protein kinase pathway. Collectively, our study demonstrates that modifications of CUX1 expression lead to aberrant expression of type I collagen, which may provide a molecular basis for fibrogenesis.
Transport activity–dependent intracellular sorting of the yeast general amino acid permease
Authors: Cain Natalie E. , Kaiser Chris A.
Published: April 2011

Intracellular trafficking of the general amino acid permease, Gap1p, of Saccharomyces cerevisiae is regulated by amino acid abundance. When amino acids are scarce Gap1p is sorted to the plasma membrane, whereas when amino acids are abundant Gap1p is sorted from the trans-Golgi through the multivesicular endosome (MVE) and to the vacuole. Here we test the hypothesis that Gap1p itself is the sensor of amino acid abundance by examining the trafficking of Gap1p mutants with altered substrate specificity and transport activity. We show that trafficking of mutant Gap1pA297V, which does not transport basic amino acids, is also not regulated by these amino acids. Furthermore, we have identified a catalytically inactive mutant that does not respond to complex amino acid mixtures and constitutively sorts Gap1p to the plasma membrane. Previously we showed that amino acids govern the propensity of Gap1p to recycle from the MVE to the plasma membrane. Here we propose that in the presence of substrate the steady-state conformation of Gap1p shifts to a state that is unable to be recycled from the MVE. These results indicate a parsimonious regulatory mechanism by which Gap1p senses its transport substrates to set an appropriate level of transporter activity at the cell surface.
Deconstructing the ßcatenin destruction complex: mechanistic roles for the tumor suppressor APC in regulating Wnt signaling
Authors: Roberts David M. , Pronobis Mira I. , Poulton John S. , Waldmann Jon D. , Stephenson Elise M. , Hanna Shahnaz , Peifer Mark
Published: April 2011

Negatively regulating signaling by targeting key effectors for ubiquitina­tion/destruction is essential for development and oncogenesis. The tumor suppressor adenomatous polyposis coli (APC), an essential negative regulator of Wnt signaling, provides a paradigm. APC mutations occur in most colon cancers. Acting in the “destruction complex” with Axin, glycogen synthase kinase 3, and casein kinase, APC targets ßcatenin (ßcat) for phosphorylation and recognition by an E3 ubiquitin-ligase. Despite 20 years of work, the internal workings of the destruction complex and APC's role remain largely mysterious. We use both Drosophila and colon cancer cells to test hypotheses for APC's mechanism of action. Our data are inconsistent with current models suggesting that high-affinity ßcat-binding sites on APC play key roles. Instead, they suggest that multiple ßcat-binding sites act additively to fine-tune signaling via cytoplasmic retention. We identify essential roles for two putative binding sites for new partners—20-amino-acid repeat 2 and conserved sequence B—in destruction complex action. Finally, we demonstrate that APC interacts with Axin by two different modes and provide evidence that conserved sequence B helps ensure release of APC from Axin, with disassembly critical in regulating ßcat levels. Using these data, we suggest a new model for destruction complex action in development, which also provides new insights into functions of truncated APC proteins in cancer.
The palmitoyl transferase DHHC2 targets a dynamic membrane cycling pathway: regulation by a C-terminal domain
Authors: Greaves Jennifer , Carmichael Juliet A. , Chamberlain Luke H.
Published: April 2011

Intracellular palmitoylation dynamics are regulated by a large family of DHHC (Asp-His-His-Cys) palmitoyl transferases. The majority of DHHC proteins associate with endoplasmic reticulum (ER) or Golgi membranes, but an interesting exception is DHHC2, which localizes to dendritic vesicles of unknown origin in neurons, where it regulates dynamic palmitoylation of PSD95. Dendritic targeting of newly synthesized PSD95 is likely preceded by palmitoylation on Golgi membranes by DHHC3 and/or DHHC15. The precise intracellular distribution of DHHC2 is presently unclear, and there is very little known in general about how DHHC proteins achieve their respective localizations. In this study, membrane targeting of DHHC2 in live and fixed neuroendocrine cells was investigated and mutational analysis employed to define regions of DHHC2 that regulate targeting. We report that DHHC2 associates with the plasma membrane, Rab11-positive recycling endosomes, and vesicular structures. Plasma membrane integration of DHHC2 was confirmed by labeling of an extrafacial HA epitope in nonpermeabilized cells. Antibody-uptake experiments suggested that DHHC2 traffics between the plasma membrane and intracellular membranes. This dynamic localization was confirmed using fluorescence recovery after photo-bleaching analysis, which revealed constitutive refilling of the recycling endosome (RE) pool of DHHC2. The cytoplasmic C-terminus of DHHC2 regulates membrane targeting and a mutant lacking this domain was associated with the ER. Although DHHC2 is closely related to DHHC15, these proteins populate distinct membrane compartments. Construction of chimeric DHHC2/DHHC15 proteins revealed that this difference in localization is a consequence of divergent sequences within their C-terminal tails. This study is the first to highlight dynamic cycling of a mammalian DHHC protein between clearly defined membrane compartments, and to identify domains that specify membrane targeting of this protein family.
DIME: R-package for identifying differential ChIP-seq based on an ensemble of mixture models
Authors: Taslim Cenny , Huang Tim , Lin Shili
Published: April 2011

Summary: Differential Identification using Mixtures Ensemble (DIME) is a package for identification of biologically significant differential binding sites between two conditions using ChIP-seq data. It considers a collection of finite mixture models combined with a false discovery rate (FDR) criterion to find statistically significant regions. This leads to a more reliable assessment of differential binding sites based on a statistical approach. In addition to ChIP-seq, DIME is also applicable to data from other high-throughput platforms.

Availability and implementation: DIME is implemented as an R-package, which is available at http://www.stat.osu.edu/~statgen/SOFTWARE/DIME. It may also be downloaded from http://cran.r-project.org/web/packages/DIME/.

Contact:  shili@stat.osu.edu
EpiGPU: exhaustive pairwise epistasis scans parallelized on consumer level graphics cards
Authors: Hemani Gibran , Theocharidis Athanasios , Wei Wenhua , Haley Chris
Published: April 2011

Motivation: Hundreds of genome-wide association studies have been performed over the last decade, but as single nucleotide polymorphism (SNP) chip density has increased so has the computational burden to search for epistasis [for n SNPs the computational time resource is O(n(n−1)/2)]. While the theoretical contribution of epistasis toward phenotypes of medical and economic importance is widely discussed, empirical evidence is conspicuously absent because its analysis is often computationally prohibitive. To facilitate resolution in this field, tools must be made available that can render the search for epistasis universally viable in terms of hardware availability, cost and computational time.

Results: By partitioning the 2D search grid across the multicore architecture of a modern consumer graphics processing unit (GPU), we report a 92× increase in the speed of an exhaustive pairwise epistasis scan for a quantitative phenotype, and we expect the speed to increase as graphics cards continue to improve. To achieve a comparable computational improvement without a graphics card would require a large compute-cluster, an option that is often financially non-viable. The implementation presented uses OpenCL—an open-source library designed to run on any commercially available GPU and on any operating system.

Availability: The software is free, open-source, platform-independent and GPU-vendor independent. It can be downloaded from http://sourceforge.net/projects/epigpu/.

Contact:  gib.hemani@roslin.ed.ac.uk
First Report of Pantoea agglomerans Causing Brown Apical Necrosis of Walnut in China
Authors: Yang K. Q. , Qu W. W. , Liu X. , Liu H. X. , Hou L. Q.
Published: April 2011

Brown apical necrosis (BAN) of walnut (Juglans regia L.) causes premature fruit drop and yield losses and has been reported to be an important walnut production problem in Spain, Italy, France, and Turkey (1,2). A number of organisms have been associated with BAN on walnut: Xanthomonas arboricola pv. juglandis, Fusarium spp., and Alternaria spp. (3). Since the spring of 2007, BAN was observed in 50 to 60% of the trees in walnut orchards in Taian City and Laiwu City, Shandong Province, China. Surface-disinfested tissue from premature walnut fruits was placed onto potato dextrose agar. Alternaria spp., X. arboricola pv. juglandis, and Pantoea agglomerans (formerly Enterobacter agglomerans) were isolated 76, 35, and 45% of the time, respectively. The P. agglomerans cultures formed a yellow lawn and were rod shaped with the body length of 1.5 to 3.0 μm, width of 0.5 to 1.0 μm, and four to six flagella. In biochemical tests, these bacteria were gram negative, lactose positive, and indole negative. Genomic DNA was extracted from one HXJ isolate and the 16S rRNA gene sequence (GenBank Accession No. HM016799) was obtained using universal primers 27F and 1492R. HM016799 had 99% sequence identity with P. agglomerans accessions in GenBank (GU477762, GQ494018, FJ756355, and AB004757). To confirm pathogenicity, HXJ isolate (108 CFU·ml–1) was inoculated at the bottom of the stigma within 5 days after florescence (DAF) and in premature fruit wounded with a needle within 30 DAF in 2008 to 2010. Stigmas injected with only sterile water served as controls. The bacteria were inoculated into three replicate 9-year-old plants of the walnut cv. Xiangling. Forty nuts on each plant were inoculated. The plants were grown in Shandong Province, China (36°09′59″N, 117°13′30″E). Ten days after inoculation, typical internal BAN symptoms were observed on all treated nuts and the controls were still healthy. In the inoculated stigmas, necrosis of stigma and style spread to internal tissues and reached the kernel. In treated premature fruit, internal tissues became necrotic and blackish and eventually led to nut drop. The same bacterium was reisolated from the inoculated tissue. On the basis of morphological, physiological, and biochemical characteristics and sequencing of the 16S rRNA gene, the bacterium was identified as P. agglomerans. To our knowledge, this is the first report of P. agglomerans causing internal type BAN of walnut in China or worldwide.

References: (1) A. Belisario et al. Plant Dis. 6:599, 2002. (2) G. Bouvet. Acta Hortic. 705:447, 2005. (3) C. Moragrega and H. Özaktan. J. Plant Pathol. 92:S1.67, 2010.
Field Damage to Yellow Starthistle Infected by Synchytrium solstitiale, and Greenhouse Maintenance and Host Range of the Fungus
Authors: Eskandari F. M. , Bruckart W. L. , Widmer T. L.
Published: April 2011

Yellow starthistle (YST, Centaurea solstitialis) is a major weed pest of the western United States. Synchytrium solstitiale, a pathogen of YST, caused significant damage to symptomatic (versus asymptomatic) plants in a field study in France. Before it was evaluated as a candidate for biological control of YST in the United States, protocols for pathogen maintenance under greenhouse conditions were developed. Maintenance, increase, and host range determination protocols involved incubation at 10/15°C (night/day) with an 8-h photoperiod either of potted or exhumed (i.e., roots of 4-week-old plants grown in flasks of water) plants inoculated with galled leaf tissue, or potted plants in which inoculum was wrapped within healthy leaves by a plastic wrap. The leaf-wrap protocol, used during the host range determination, always resulted in disease of YST. Several safflower (Carthamus tinctorius) cultivars and other plants related to YST became diseased following this protocol, thus raising concern about host specificity. Development of disease on nontarget species precludes proposal of S. solstitiale for biological control of YST at this time.
First Report of a 16SrII-D Subgroup Phytoplasma Associated with Pale Purple Coneflower Witches'-Broom Disease in Australia
Authors: Pearce T. L. , Scott J. B. , Pethybridge S. J.
Published: April 2011

Pale purple coneflower, Echinacea pallida (Nutt.) Nutt., is an herbaceous perennial cultivated for its ornamental and medicinal properties. In 2005, phytoplasma-like symptoms, including virescence, phyllody, and chlorotic leaves, were first observed in coneflower fields in northern Tasmania, Australia. During the 2010–2011 growing season, the incidence of affected plants was estimated to be 12% within a single field. Total DNA was extracted from symptomatic plants with a DNeasy Plant Mini Kit (QIAGEN Inc., Valencia, CA) according to the manufacturer's instructions. DNA was also extracted, as described above, from asymptomatic coneflower seedlings obtained by germinating surface-sterilized seed on water agar. DNA was amplified via a nested PCR using universal primer pairs P1/P7 followed by R16F2n/R16R2 to detect putative phytoplasmas (2). Amplifications yielded expected products of 1.8 and 1.2 kb, respectively, only from symptomatic samples. Subsequently, PCR products from six arbitrarily selected samples were used for sequencing (Genome Lab Dye Terminator Cycling Sequence with Quick Start Chemistry) and read in a CEQ8000 sequencer (Beckman Coulter Inc., Brea, CA). Sequence homology indicated 100% similarity between isolates designated EWB1 to EWB4 (GenBank Accession Nos. JF340075 and JF340077 to JF340079) and between EWB5 and EWB6 (JF340076 and JF40080). Sequence homology between the two observed groups was 99.7%, resulting from a 4-bp difference in the R16F2n primer region. Blast search revealed isolates EWB1 to EWB4 were 100% homologous with Catharanthus roseus phytoplasma (EU096500.1), Tomato big bud phytoplasma (EF193359.1), Scaevola witches'-broom phytoplasma (AB257291.1), and Mollicutes sp. (Y10097.1 and Y10096.1). Moreover, isolates EWB5 and EWB6 shared 99% sequence identity with the above isolates. iPhyClassifier (4) was used to perform sequence similarity and generate virtual restriction fragment length polymorphism (RFLP) profiles. The 16S rDNA sequence of isolates EWB1 to EWB4 and EWB5 to EWB6 shared 100 and 99.7% similarity, respectively, to the ‘Candidatus Phytoplasma australasiae’ reference strain (Y10097). RFLP profiles from all isolates suggested that they belonged to the 16SrII-D subgroup. To our knowledge, this is the first report of a 16SrII-D subgroup phytoplasma infecting E. pallida in Australia. Aster yellow phytoplasmas (16SrI-C subgroup) infections of E. purpurea have been recorded in Slovenia (3) and southern Bohemia (1).

References: (1) J. Franova et al. Eur. J. Plant Pathol. 123:85, 2009. (2) I. M. Lee et al. Int. J. Syst. Bacteriol. 48:1153, 1998. (3) S. Radišek et al. Plant Pathol. 58:392, 2009. (4) Y. Zhao et al. Int. J. Syst. Evol. Microbiol. 59:2582, 2009.
Effect of Application Method and Rate on Residual Efficacy of Mefenoxam and Phosphorous Acid Fungicides in the Control of Pink Rot of Potato
Authors: Taylor Raymond J. , Pasche Julie S. , Gudmestad Neil C.
Published: April 2011

Experiments were conducted to examine the effectiveness of rate and method of phosphorous acid application for controlling pink rot of potato (Solanum tuberosum) caused by Phytophthora erythroseptica. Replicated small-plot and replicated split commercial field trials were established in commercial production fields in Minnesota from 2006 to 2009. Fungicides were applied in-furrow at planting, or as one, two, or three foliar applications via ground sprayer, irrigation system (chemigation), or fixed-wing aircraft. Phosphorous acid efficacy was compared to mefenoxam, the fungicide commonly utilized to manage pink rot, either by determining natural infections in the field or by inoculating eyes of harvested tubers using a mefenoxam-sensitive and -resistant isolate of P. erythroseptica via postharvest challenge inoculation. In replicated small plot trials, both in-furrow and two foliar applications of mefenoxam controlled tuber rot in the field, and significantly controlled tuber rot in storage. Phosphorous acid also reduced tuber rot in the field when applied two or three times to the foliage. Although phosphorous acid was ineffective when applied in-furrow, one, two, and three foliar applications and a postharvest application of phosphorous acid controlled mefenoxam-sensitive and -resistant isolates of P. erythroseptica during storage for 187 days, while mefenoxam failed to control the resistant isolate. In replicated split commercial field trials, two aerial applications of phosphorous acid were as effective as three applications in reducing pink rot incidence in tubers inoculated postharvest. Three aerial applications were as effective as three chemigation applications in replicated split commercial field trials in 2008, but provided significantly greater protection than chemigation in 2009.