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Search Results: 1 - 10 of 1700 matches for " Laurence Dinan "
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Synthesis and biological activities of turkesterone 11?-acyl derivatives
Laurence Dinan,Pauline Bourne,Pensri Whiting,Ada Tsitsekli
Journal of Insect Science , 2003,
Abstract: Turkesterone is a phytoecdysteroid possessing an 11alpha-hydroxyl group. It is an analogue of the insect steroid hormone 20-hydroxyecdysone. Previous ecdysteroid QSAR and molecular modelling studies predicted that the cavity of the ligand-binding domain of the ecdysteroid receptor would possess space in the vicinity of C-11/C-12 of the ecdysteroid. We report the regioselective synthesis of a series of turkesterone 11alpha-acyl derivatives in order to explore this possibility. The structures of the analogues have been unambiguously determined by spectroscopic means (NMR and low-resolution mass spectrometry). Purity was verified by HPLC. Biological activities have been determined in Drosophila melanogaster BII cell-based bioassay for ecdysteroid agonists and in an in vitro radioligand-displacement assay using bacterially expressed D. melanogaster EcR/USP receptor proteins. The 11alpha-acyl derivatives do retain a significant amount of biological activity relative to the parent ecdysteroid. Further, although activity initially drops with the extension of the acyl chain length (C2 to C4), it then increases (C6 to C10), before decreasing again (C14 and C20). The implications of these findings for the interaction of ecdysteroids with the ecdysteroid receptor and potential applications in the generation of affinity-labelled and fluorescently-tagged ecdysteroids are discussed.
Practical uses for ecdysteroids in mammals including humans: An update
R. Lafont,L. Dinan
Journal of Insect Science , 2003,
Abstract: Ecdysteroids are widely used as inducers for gene-switch systems based on insect ecdysteroid receptors and genes of interest placed under the control of ecdysteroid-response elements. We review here these systems, which are currently mainly used in vitro with cultured cells in order to analyse the role of a wide array of genes, but which are expected to represent the basis for future gene therapy strategies. Such developments raise several questions, which are addressed in detail.
Continuous Maps on Digital Simple Closed Curves  [PDF]
Laurence Boxer
Applied Mathematics (AM) , 2010, DOI: 10.4236/am.2010.15050
Abstract: We give digital analogues of classical theorems of topology for continuous functions defined on spheres, for digital simple closed curves. In particular, we show the following. ? A digital simple closed curve of more than 4 points is not contractible, i.e., its identity map is not nullhomotopic in . ? Let and be digital simple closed curves, each symmetric with respect to the origin, such that (where is the number of points in ). Let be a digitally continuous antipodal map. Then is not nullho- motopic in . ? Let be a digital simple closed curve that is symmetric with respect to the origin. Let be a digitally continuous map. Then there is a pair of antipodes such that .
Resistance to Early-Life Stress in Mice: Effects of Genetic Background and Stress Duration
Timothy G. Dinan,John F. Cryan
Frontiers in Behavioral Neuroscience , 2011, DOI: 10.3389/fnbeh.2011.00013
Abstract: Early-life stress can induce marked behavioral and physiological impairments in adulthood including cognitive deficits, depression, anxiety, and gastrointestinal dysfunction. Although robust rat models of early-life stress exist there are few established effective paradigms in the mouse. Genetic background and protocol parameters used are two critical variables in such model development. Thus we investigated the impact of two different early-life stress protocols in two commonly used inbred mouse strains. C57BL/6 and innately anxious BALB/c male mice were maternally deprived 3 h daily, either from postnatal day 1 to 14 (protocol 1) or 6 to 10 (protocol 2). Animals were assessed in adulthood for cognitive performance (spontaneous alternation behavior test), anxiety [open-field, light/dark box (L/DB), and elevated plus maze (EPM) tests], and depression-related behaviors (forced swim test) in addition to stress-sensitive physiological changes. Overall, the results showed that early-life stressed mice from both strains displayed good cognitive ability and no elevations in anxiety. However, paradoxical changes occurred in C57BL/6 mice as the longer protocol (protocol 1) decreased anxiety in the L/DB and increased exploration in the EPM. In BALB/c mice there were also limited effects of maternal separation with both separation protocols inducing reductions in stress-induced defecation and protocol 1 reducing the colon length. These data suggest that, independent of stress duration, mice from both strains were on the whole resilient to the maladaptive effects of early-life stress. Thus maternal separation models of brain–gut axis dysfunction should rely on either different stressor protocols or other strains of mice.
Modelling Visible Foliar Injury Effects on Canopy Photosynthesis and Potential Crop Yield Losses Resulting from Fluoride Exposure  [PDF]
David Doley, Laurence Rossato
Journal of Environmental Protection (JEP) , 2012, DOI: 10.4236/jep.2012.39113
Abstract: Crop production models are highly developed to account for different nitrogen, light, temperature and water availability conditions and, in some species, disease or air pollutant effects. There is very limited knowledge on responses of many tropical crops, such as oil palm (Elaeis guineensis), to air pollutants although predictions of these effects are essential for industrial planning in several countries. In the absence of limitations due to water supply, the effects of leaf area loss due to necrosis and chlorosis are much more important to canopy photosynthesis than are changes in the physiological attributes that influence the efficiency of light use. Therefore, potential losses of crop production due to air pollutants such as fluoride can be inferred usefully from the extent of visible injury to foliage that may be associated with different levels of pollutant exposure.
The Cross-Sectional Risk Premium of Decomposed Market Volatility in UK Stock Market  [PDF]
Yan Yang, Laurence Copeland
Open Journal of Social Sciences (JSS) , 2014, DOI: 10.4236/jss.2014.27006
Abstract:

We decompose UK market volatility into short- and long-run components using EGARCH component model and examine the cross-sectional prices of the two components. Our empirical results suggest that these two components are significantly priced in the cross-section and the negative risk premia are consistent with the existing literature. The Fama-French three-factor model is improved by the inclusion of the two volatility components. However, our ICAPM model using market excess return and the decomposed volatility components as state variables compares inferiorly to the traditional three-factor model.

Guardians and Targets: A Routine Activity Approach to Terrorism in Southeast Asia  [PDF]
Camille Laurence Pauline Bigot
Open Journal of Social Sciences (JSS) , 2017, DOI: 10.4236/jss.2017.512011
Abstract:
Since 9/11, terrorism has been an important subject of study within the political and social fields, having often been examined critically. However, empirical frameworks have been lacking within the study of terrorism. This paper aims to counter reductionist views of terrorism and provide a holistic analysis under the arch of a criminological ontological framework. This study tests the relevance of routine activity theory to terrorism, taking the specific case study of terrorism within Southeast Asia. Working with Interpol, terror attacks, and counter-terrorism operations were quantified to mathematically model Routine Activity Theory where I aimed to find predictive terror patterns. Using a time-series analysis of terrorist attacks and counter-terrorism operations, Deterrence Theory, Randomness Theory in targeting and Contagion theory will be tested. A comparative framework will be established between religious attacks and politically related ones. My research aims to disprove any discursive assumptions of terrorism through a quantitative empirical focus. Furthermore, it aims to find patterns within terrorism to learn how to better combat it.
El papel de los antidepresivos en el manejo del síndrome de intestino irritable
Quigley,Eamonn MM; Craig,Orla F; Dinan,Timothy G;
Revista Colombiana de Gastroenterologia , 2011,
Abstract: irritable bowel syndrome (ibs) is a complex entity whose etiology is unknown and whose physiopathology is incompletely known. it occurs frequently, and many treatments for it have been described. the relation of psycho-social factors to the genesis and presentation of ibs has been studied with special attention. the approach to treating ibs patients requires contemplation of the patient?s symptoms and reactions to his or her illness and environment. of the multiple treatments for ibs which have been described, antidepressants have received considerable attention although their clinical utility is still not clear. the objective of this work is to review the literature regarding the physiopathological basis of ibs, comorbidities with psychiatric disorders, and the clinical usefulness of antidepressants for treating irritable bowel syndrome.
El papel de los antidepresivos en el manejo del síndrome de intestino irritable The role of antidepressants in the management of irritable bowel syndrome (IBS)
Eamonn MM Quigley,Orla F Craig,Timothy G Dinan
Revista Colombiana de Gastroenterologia , 2011,
Abstract: El síndrome de intestino irritable es una entidad compleja, de etiología desconocida y fisiopatología parcialmente comprendida, de frecuente ocurrencia y con múltiples tratamientos descritos. Se ha estudiado especialmente la relación de los factores psicosociales con la génesis y presentación de la entidad. El paciente requiere un enfoque que contemple sus síntomas, la reacción ante su enfermedad y su entorno. De los múltiples tratamientos descritos, los medicamentos antidepresivos han recibido considerable atención pero su utilidad clínica no es clara. El objetivo del presente trabajo es realizar una revisión enfocada de la literatura sobre las bases fisiopatológicas, la presencia de comorbilidad psiquiátrica y la utilidad clínica del uso de antidepresivos en este síndrome. Irritable Bowel Syndrome (IBS) is a complex entity whose etiology is unknown and whose physiopathology is incompletely known. It occurs frequently, and many treatments for it have been described. The relation of psycho-social factors to the genesis and presentation of IBS has been studied with special attention. The approach to treating IBS patients requires contemplation of the patient’s symptoms and reactions to his or her illness and environment. Of the multiple treatments for IBS which have been described, antidepressants have received considerable attention although their clinical utility is still not clear. The objective of this work is to review the literature regarding the physiopathological basis of IBS, comorbidities with psychiatric disorders, and the clinical usefulness of antidepressants for treating irritable bowel syndrome.
Purification and biochemical properties of a salivary α-amylase in Andrallus spinidens Fabricius (Hemiptera: Pentatomidae)
A Zibaee,H Hoda,M Fazeli-Dinan
Invertebrate Survival Journal , 2012,
Abstract: α-amylase is one of the enzymes that has crucial role in extra-oral digestion (EOD) of hemipteran insects. An α-amylase was purified and biochemically characterized from the salivary glands of Andrallus spinidens showing its considerable role in EOD process. It was found an enzyme by specific activity of 4.22 U/mg protein, recovery of 14.67 % and purification fold of 13.83-fold as well as molecular weight of 26 kDa. By using two buffer solutions, optimal pH of the purified α-amylase was found to be 9 for both universal and Tris-HCl buffers. Our findings revealed that the purified α-amylase had the highest activity at the temperatures of 35 and 40 °C, and were stable for 96 h at these temperatures. Kinetic parameters of the purified enzyme show that both starch and glycogen, are the suitable substrates for the enzymatic assay, but a lower Km demonstrated glycogen as a more appropriate substrate. Among the cations used to show their possible involvement in active site of the enzyme, Ca2+2+, Mg and one concentration of Cu2+ increased the α-amylase activity but Na+ decreased the enzyme activity. Triton X-100 increased the enzyme activity but SDS, EDTA, EGTA and TTHA decreased it, indicating involvement of metal ions in the active site of the purified α-amylase.
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