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Great Interest (great + interest)
Selected AbstractsSynthesis, Structure, and Properties of Single-Walled Carbon NanotubesADVANCED MATERIALS, Issue 45 2009Weiya Zhou Abstract Great interest in single-walled carbon nanotubes (SWCNTs) derives from their remarkable electrical, thermal, optical, and mechanical properties together with their lower density, which promise extensive and unique applications. Much progress has been achieved in the fundamental and applied investigations of SWCNTs over the past decade. At the same time, many obstacles still remain, hampering further development in this field. To clarify the emerging problems and to provide a comprehensive understanding of the field, we review the recent progress of research on the synthesis, structure, and properties of SWCNTs, in particular the SWCNT non-woven film, SWCNT rings, boron,nitrogen (B,N) co-doped SWCNTs (BCN-SWNTs), and individual SWCNTs. Some long-standing problems and topics warranting further investigations in the near future are addressed. [source] Suitability of bifidobacteria and thymol as biopreservatives in extending the shelf life of fresh packed plaice filletsJOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2005C. Altieri Abstract Aims:, The present study was aimed to evaluate the microbiological and sensory characteristics of biopreserved packed fresh plaice (Pleuronectes platessa), during storage. Methods and Results:, Fish samples were treated with a Bifidobacterium bifidum strain and thymol as preservatives, stored at different temperatures (4 and 12°C) and package atmospheres (in air, under vacuum, modified atmosphere). Data about the total viable count (TVC) were used to predict the shelf life of the fish fillets as affected by the preservatives used and the storage conditions. Data obtained revealed that B. bifidum could perform an efficient synergy with thymol, in controlling the hygiene biological markers. Besides, the tested bifidobacterial species, combined with low storage temperature and anoxia/hypoxia, showed a great efficacy against the main fresh packaged fish spoilage species (Pseudomonas spp., Photobacterium phosphoreum). Conclusions:, The studied technique could be considered effective in fresh fish spoilage control. Significance and Impact of the Study:, Great interest is developing on food biopreservation, because of the ever increasing needs to protect consumers' and environment's health, and to revalorize some important food characteristics, such as naturalness and authenticity, without leaving the safety aside. [source] STRATEGIES FOR PROLONGING THE SHELF LIFE OF MINCED BEEF PATTIESJOURNAL OF FOOD SAFETY, Issue 1 2009MATTEO ALESSANDRO DEL NOBILE ABSTRACT The study of different strategies for prolonging the shelf life of fresh minced beef patties was addressed in this work. Fresh minced beef was supplemented with thymol (THY) at levels of 250, 500 and 750 mg per kg of ground beef. Treated samples were packed using a high barrier film and stored in refrigerated conditions (4C) under ordinary atmosphere packaging and modified atmosphere packaging (MAP) conditions for 16 days. The microbiological quality decay kinetic was determined by monitoring the following microorganisms: Enterobacteriaceae, Pseudomonas spp., lactic acid bacteria, Brochothrix thermosphacta, coliforms and total psychrotrophic viable count. Results show that THY, working alone, was effective on coliforms and Enterobacteriaceae, whereas it does not seem to inhibit to a great extent the growth of the other microbial populations. On the other hand, an increased amount of THY, under MAP conditions, had better effects on the product quality, with a consequent prolongation of the shelf life. PRACTICAL APPLICATIONS Great interest is developing in food bio-preservation, because of the ever-increasing needs to protect consumers' health and to valorize the naturalness and safety of food products. However, very few works have been carried out on the applications of bio-preservatives to extend the shelf life of fresh meat products. This study, therefore, was mainly initiated to evaluate the possibility of extending the shelf life of packed fresh meat patties by a combination of thymol (THY) to other extrinsic factors such as storage temperatures and modified atmosphere during packaging. Interesting results were obtained suggesting that THY can perform an efficient synergy with modified atmosphere conditions and could be advantageously utilized by the meat industry. [source] Use of Lysozyme, Nisin, and EDTA Combined Treatments for Maintaining Quality of Packed Ostrich PattiesJOURNAL OF FOOD SCIENCE, Issue 3 2010Marianna Mastromatteo ABSTRACT:, The antimicrobial effectiveness of lysozyme, nisin, and ethylene diamine tetraacetic acid (EDTA) combination treatments (Mix1: 250 ppm lysozyme, 250 ppm nisin, 5 mM EDTA; Mix2: 500 ppm lysozyme, 500 ppm nisin, 5 mM EDTA) on bacterial growth of ostrich patties packaged in air, vacuum, and 2 different modified atmospheres (MAP1: 80% O2, 20% CO2; MAP2: 5% O2, 30% CO2, 65% N2) was evaluated. Moreover, the lipid oxidation was evaluated as well as color and sensory characteristics. The growth of total viable counts and lactic acid bacteria were strongly inhibited by the antimicrobial treatments in all the running time (Inhibition Index >97%) whereas for Enterobacteriaceae,and Pseudomonas,spp. lower inhibition indices from 12% to about 28% were observed. The lipid oxidation was more pronounced in the control respect to the treated meat patties. Moreover, the mixture at low concentration of lysozyme and nisin showed the best antioxidative effect. High concentrations of lysozyme and nisin showed the greatest color loss. Also, off-odors for the untreated patties developed faster than the treated samples. Practical Application: Great interest is developing in food bio-preservation, because of the ever-increasing needs to protect consumers' health and to valorize the naturalness and safety of food products. [source] Improved synthesis of DOTA tetraamide ligands for lanthanide(III) ions: A tool for increasing the repertoire of potential PARACEST contrast agents for MRI and/or fluorescent sensorsCONTRAST MEDIA & MOLECULAR IMAGING, Issue 3 2010Luis M. De León-Rodríguez Abstract The synthesis of new DOTA tetraamide (DOTAMR4) compounds is of great interest given their application in the formation of Ln(III) complexes as potential PARACEST contrast agents in MRI or fluorescent molecular probes. In this context amino acid and peptide DOTAMR4 derivatives are particularly attractive since the amino-acid and/or peptide moiety can show responsive properties dependent on a given stimuli which might translate to changes in water exchange rates of the corresponding Ln(III) complex. Current synthesis of DOTAMR4 derivatives is typically carried out by reacting haloacetamide intermediates with cyclen. However, this method fails to generate the tetra-substituted products when bulky substituents are present in the haloacetamide and in some cases this intermediate cannot be prepared by conventional acylation procedures limiting the number of DOTAMR4 compounds available for study. As a solution to these limitations, an improved methodology for the synthesis of DOTAMR4 by coupling DOTA to an appropriate amine containing reagent (i.e. protected amino-acids with the , -amino group free) is presented in this work. Several DOTAMR4 derivatives which are difficult or impossible to prepare with the traditional methodologies were easily obtained starting with DOTA. A new protocol was derived using this methodology for the solution-phase synthesis of DOTA peptide derivatives. With this methodology, many other DOTAMR4 peptide and non-peptide derivatives have been prepared in our laboratories with several of these new compounds showing interesting properties for molecular imaging. Copyright © 2010 John Wiley & Sons, Ltd. [source] Force propagation and force generation in cells,CYTOSKELETON, Issue 9 2010Oliver Jonas Abstract Determining how forces are produced by and propagated through the cytoskeleton (CSK) of the cell is of great interest as dynamic processes of the CSK are intimately correlated with many molecular signaling pathways. We are presenting a novel approach for integrating measurements on cell elasticity, transcellular force propagation, and cellular force generation to obtain a comprehensive description of dynamic and mechanical properties of the CSK under force loading. This approach uses a combination of scanning force microscopy (SFM) and Total Internal Reflection Fluorescence (TIRF) microscopy. We apply well-defined loading schemes onto the apical cell membrane of fibroblasts using the SFM and simultaneously use TIRF microscopy to image the topography of the basal cell membrane. The locally distinct changes of shape and depth of the cytoskeletal imprints onto the basal membrane are interpreted as results of force propagation through the cytoplasm. This observation provides evidence for the tensegrity model and demonstrates the usefulness of our approach that does not depend on potentially disturbing marker compounds. We confirm that the actin network greatly determines cell stiffness and represents the substrate that mediates force transduction through the cytoplasm of the cell. The latter is an essential feature of tensegrity. Most importantly, our new finding that, both intact actin and microtubule networks are required for enabling the cell to produce work, can only be understood within the framework of the tensegrity model. We also provide, for the first time, a direct measurement of the cell's mechanical power output under compression at two femtowatts. © 2010 Wiley-Liss, Inc. [source] Collagen Remodeling After 585-nm Pulsed Dye Laser Irradiation: An Ultrasonographic AnalysisDERMATOLOGIC SURGERY, Issue 10 2003Brent R. Moody MD Background and Objectives. Nonablative dermal remodeling is an evolving technology that has generated great interest among both laser surgeons and patients. Evidence indicates that dermal collagen formation is the key mechanism of action for the nonablative techniques. We studied, with ultrasound, new collagen formation after nonablative laser irradiation. Methods. Ten patients with facial rhytids underwent a single treatment with a 585-nm pulsed dye laser. The patients were all female, ranging in age from 47 to 67, and were Fitzpatrick skin types I,III. Laser parameters were as follows: an energy fluence of 2.4 to 3.0 J/cm2, a pulse duration of 350 ,sec, and a spot size of 5 mm with no overlap. Ultrasonographic assessments of dermal collagen were taken at baseline and at 30 and 90 days after treatment. Results. Ultrasonography demonstrated an increase in dermal collagen after a single treatment with the 585-nm pulsed dye laser. The greatest degree of neocollagenesis occurred periocularly. Conclusion. A single treatment with a 585-nm pulsed dye laser appears to increase dermal collagen. This increase in dermal collagen can be assessed with noninvasive cutaneous ultrasound. [source] The use of population based registers in psychiatric researchACTA PSYCHIATRICA SCANDINAVICA, Issue 5 2009P. AllebeckArticle first published online: 6 OCT 200 Objective:, Much of the knowledge we now take for granted regarding major mental disorders such as schizophrenia, suicide and other disorders, would not exist without the use of population based registers. The use of population based registers in psychiatric epidemiology have enabled analyses of associations that otherwise would not have been possible to address. Method:, The use of registers in psychiatric research is described, exemplified, and discussed. Results:, Methodological and validity aspects depend to a large part on the type of register being considered. A classification is proposed of different types of registers, each one implying specific methodological issues. These can be addressed according to the dimensions coverage, attrition, representativity and validity. Specific methodological consideration has still to be taken in relation to each specific research question. Thus, special validity studies usually need to be performed when embarking on studies using population based registers. Conclusion:, With increasing burden of disease due to mental disorders worldwide, knowledge of the epidemiology of these disorders are of increasing interest. The Nordic countries have a strong history in this field of research, of great interest to the rest of the world. Universities and research funding agencies should recognize this valuable source of research capacity, and support fruitful continuation of a strong tradition. [source] Cardiovascular drugs as antidiabetic agents: evidence for the prevention of type 2 diabetesDIABETES OBESITY & METABOLISM, Issue 7 2008D. P. Macfarlane Given the long-term health consequences and increasing incidence of type 2 diabetes, there is great interest to potentially prevent or delay its onset. Primary prevention studies have demonstrated that intensive exercise and weight reduction, and to a lesser extent certain antidiabetic agents, can reduce new onset diabetes in at-risk individuals. Results from post hoc analyses and secondary end-point outcomes of large randomized controlled trials of cardiovascular drugs suggest that these may also have beneficial effects, reducing the incidence of new onset diabetes in addition to their proven cardiovascular benefits. Multiple meta-analyses confirm that drugs primarily acting on the renin,angiotensin system (RAS) reduce the incidence of diabetes in the populations studied, perhaps via improved insulin sensitivity and/or effects on pancreatic beta cells. However, results from the recent Diabetes REduction Approaches with Medication study specifically failed to show a significant reduction in the incidence of diabetes with ramipril in individuals with abnormal glucose tolerance at baseline. There is only limited evidence that statins improve glucose tolerance, and although beta-blockers tend to have detrimental effects on glucose tolerance, newer agents with vasodilatory properties may confer benefits. With current guidelines, the use of cardiovascular drugs modifying the RAS will increase in at-risk individuals, but at present, they cannot be recommended to prevent diabetes. [source] Preconditioning and postconditioning: new strategies for cardioprotectionDIABETES OBESITY & METABOLISM, Issue 6 2008D. J. Hausenloy Despite optimal therapy, the morbidity and mortality of coronary heart disease (CHD) remains significant, particularly in patients with diabetes or the metabolic syndrome. New strategies for cardioprotection are therefore required to improve the clinical outcomes in patients with CHD. Ischaemic preconditioning (IPC) as a cardioprotective strategy has not fulfilled it clinical potential, primarily because of the need to intervene before the index ischaemic event, which is impossible to predict in patients presenting with an acute myocardial infarction (AMI). However, emerging studies suggest that IPC-induced protection is mediated in part by signalling transduction pathways recruited at time of myocardial reperfusion, creating the possibility of harnessing its cardioprotective potential by intervening at time of reperfusion. In this regard, the recently described phenomenon of ischaemic postconditioning (IPost) has attracted great interest, particularly as it represents an intervention, which can be applied at time of myocardial reperfusion for patients presenting with an AMI. Interestingly, the signal transduction pathways, which underlie its protection, are similar to those recruited by IPC, creating a potential common cardioprotective pathway, which can be recruited at time of myocardial reperfusion, through the use of appropriate pharmacological agents given as adjuvant therapy to current myocardial reperfusion strategies such as thrombolysis and primary percutaneous coronary intervention for patients presenting with an AMI. This article provides a brief overview of IPC and IPost and describes the common signal transduction pathway they both appear to recruit at time of myocardial reperfusion, the pharmacological manipulation of which has the potential to generate new strategies for cardioprotection. [source] Development of spray- and freeze-dried high-concentration sesamol emulsions and antioxidant evaluation in fibroblasts and UV-exposed rat skin slicesDRUG DEVELOPMENT RESEARCH, Issue 5 2008Juliana Alencar Abstract Dry sesamol emulsions were synthesized from several combinations of saccharose with hydroxypropylmethylcellulose (HPMC) or sodium caseinate (SC) using spray-drying techniques at 120° to 180°C, or freeze-drying. On the basis of physical characteristics such as droplet size distribution, residual moisture, and microscopic structure, the best material was obtained when spray-drying was applied at either 150° or 180°C with SC or HPMC as excipients, respectively. The extent to which the antioxidant properties of free sesamol towards a set of free radicals (galvinoxyl, diphenylpicrylhydrazyl, superoxide, and hydroxyl) were altered in the starting and reconstituted liquid emulsions submitted to normal storage or pre-exposed to a flux hydroxyl radicals was investigated. Emulsions were further evaluated for their antioxidant properties in cultured 3T3 murine fibroblasts and in an ex vivo model of ultraviolet irradiated rat skin. It was found that, in the material having the best physical properties, encapsulation was decisive in: (1) improving the overall antioxidant behavior of reconstituted versus starting liquid emulsions: (2) sparing sesamol consumption due to free radical attack; and (3) significantly protecting cells and skin against free radical- or irradiation-induced enzymatic release and/or lipid peroxidation. Demonstrating a high activity at high dilutions where interactions of excipient become negligible, the new emulsions could be of great interest in sesamol-based pharmacology or topical applications. Drug Dev Res 69:251,266, 2008. © 2008 Wiley-Liss, Inc. [source] High local species richness of parasitic wasps (Hymenoptera: Ichneumonidae; Pimplinae and Rhyssinae) from the lowland rainforests of Peruvian AmazoniaECOLOGICAL ENTOMOLOGY, Issue 6 2004Ilari E. Sääksjärvi Abstract., 1. The parasitic wasp family Ichneumonidae (Hymenoptera) is of great interest because it has been claimed that its species richness does not increase with decreasing latitude. 2. No extensive studies of the family have been conducted in South American localities. 3. Arthropods were sampled using 27 Malaise traps in the Allpahuayo,Mishana National Reserve (56 000 ha) in the north-eastern Peruvian Amazonian lowland rainforest. The total duration of the sampling programme was 185 Malaise trap months. 4. Altogether, 88 species were collected. This is one of the highest local pimpline and rhyssine species numbers ever recorded. A comparison with results from Mesoamerica revealed that at equal numbers of individuals sampled, the number of Pimplinae and Rhyssinae species in Peruvian Amazonia is at least twofold compared with lowland locations in Mesoamerica and somewhat higher than in the most species-rich Costa Rican higher altitude localities. 5. Non-parametric methods of estimating species richness were applied. These suggest that additional sampling would yield a considerable number of new Pimplinae and/or Rhyssinae species. [source] Study of a Catalytic Mechanism in Additive Differential Pulse TechniquesELECTROANALYSIS, Issue 4 2003Angela Molina Abstract The new electrochemical double pulse technique, known as additive differential normal pulse voltammetry (ADNPV) when there is no restriction on the duration of both pulses, and additive differential pulse voltammetry (ADPV) when t2,t1, has been applied to a pseudo-first-order catalytic mechanism. The expressions obtained here are applicable to planar and spherical electrodes, of any radius. This is of great interest since the size of the electrode plays an important role in the preponderating of diffusive and kinetics processes. The signal obtained with this technique presents the same morphological characteristics as the triple pulse technique, double differential pulse voltammetry (DDPV) and is more advantageous than DDPV and than the double pulse one, differential pulse voltammetry (DPV). [source] Urtica dioica agglutinin: Separation, identification, and quantitation of individual isolectins by capillary electrophoresis and capillary electrophoresis,mass spectrometryELECTROPHORESIS, Issue 9 2005Markus Ganzera Abstract With benign prostatic hyperplasia (BPH) being a major health problem in ageing men, alternative therapeutic approaches (e.g., with phytopharmaceuticals) are of great interest. Based on pharmacological evidences, one of the most promising options in that respect are the lectins found in Urtica dioica (stinging nettle) roots. In this study the qualitative and quantitative analysis of individual isolectins in U. dioica extracts is described, which is the first report on using capillary electrophoresis (CE) for the analysis of lectins in plant material at all. By utilizing a 200 mM sodium acetate buffer (pH 3.75) a baseline separation and determination of four closely related isolectins was feasible within 20 min in the aqueous plant extracts. The individual compounds were identified based on reference compounds as well as data obtained from CE-mass spectrometry (MS) experiments. After modifying the optimized CE conditions to 100 mM ammonium formate buffer with pH 3.75 and a voltage of 15 kV, the isolectins were clearly assignable in positive electrospray ionization (ESI) mode. The quantitative results obtained by CE (the total lectin content varied from 0 to 0.42% in the samples) were accurate (recovery rates of spiked samples between 92.5 and 96.2%), precise (relative standard deviation < 5%) and in good agreement to those obtained by High-performance liquid chromatography (HPLC). As for peak resolution, assignable compounds and required separation time the newly developed CE method was clearly advantageous over the determination achieved by LC. [source] Metalloporphyrin solubility: A trigger for catalyzing reductive dechlorination of tetrachloroethyleneENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2004Ishai Dror Abstract Metalloporphyrins are well known for their electron-transfer roles in many natural redox systems. In addition, several metalloporphyrins and related tetrapyrrole macrocycles complexed with various core metals have been shown to catalyze the reductive dechlorination of certain organic compounds, thus demonstrating the potential for using naturally occurring metalloporphyrins to attenuate toxic and persistent chlorinated organic pollutants in the environment. However, despite the great interest in reductive dechlorination reactions and the wide variety of natural and synthetic porphyrins currently available, only soluble porphyrins, which comprise a small fraction of this particular family of organic macrocycles, have been used as electron-transfer shuttles in these reactions. Results from the present study clearly demonstrate that metalloporphyrin solubility is a key factor in their ability to catalyze the reductive dechlorination of tetrachloroethylene and its daughter compounds. Additionally, we show that certain insoluble and nonreactive metalloporphyrins can be activated as catalysts merely by changing solution conditions to bring about their dissolution. Furthermore, once a metalloporphyrin is fully dissolved and activated, tetrachloroethylene transformation proceeds rapidly, giving nonchlorinated and less toxic alkenes as the major reaction products. Results from the present study suggest that if the right environmental conditions exist or can be created, specific metalloporphyrins may provide a solution for cleaning up sites that are contaminated with chlorinated organic pollutants. [source] How well can animals navigate?ENVIRONMETRICS, Issue 4 2006Estimating the circle of confusion from tracking data Abstract State-space models have recently been shown to effectively model animal movement. In this paper we illustrate how such models can be used to improve our knowledge of animal navigation ability, something which is poorly understood. This work is of great interest when modeling the behavior of animals that are migrating, often over tremendously large distances. We use the term circle of confusion, first proposed by Kendall (1974), to describe the general inability of an animal to know its location precisely. Our modeling strategy enables us to statistically describe the circle of confusion associated with any animal movements where departure and destination points are known. For illustration, we use ARGOS satellite telemetry of leatherback turtles migrating over a distance of approximately 4000,km in the Atlantic Ocean. Robust features of the model enable one to deal with outlying observations, highly characteristic of these types of data. Although specifically designed for data obtained using satellite telemetry, our approach is generalizable to other common kinds of movement data such as archival tag data. Copyright © 2005 John Wiley & Sons, Ltd. [source] Data analysis of environmental air pollutant monitoring systems in EuropeENVIRONMETRICS, Issue 6 2004Kristina Voigt Abstract Public access to information about the environment is being strengthened across Europe. The concept of public's right to information gives the basis for the access to environmental information. In this paper the quality of air pollutant monitoring systems in the 15 European member states is analyzed. For pragmatic reasons only the capitals are looked upon. Comprehensive data on environmental monitoring programs concerning air pollutants like ozone (O3), nitrogen dioxide (NO2), nitrogen oxide (NO), carbon dioxide (CO2) and carbon monoxide (CO), and sometimes suspended dust, benzene and other environmental chemicals are available on the free Internet. As different monitoring information systems exist in the European member states a comparison of these systems with their pros and cons is of great interest to the public. Environmental air pollutant monitoring systems in the capitals of the 15 EEC member countries (objects) are evaluated by applying 5 evaluation criteria for the differentiation of these systems. The scores run from 0,=,insufficient, 1,=,medium, to 2,=,excellent. Different data-analysis methods will be applied. As order theory is still not sufficiently presented in the scientific literature, a short overview about the so-called Hasse diagram technique and POSAC method is outlined. In several steps the data-matrix is analyzed coming to the conclusion that all methods (additionally PCA is used) identify one criterion as specifically important. Not unexpected, each method has its own advantage. The aim of this data-analysis is the evaluation of the publicly available air quality monitoring systems in Europe with their pros and cons. This might help the interested public to find and understand the information given on the Internet. Furthermore our evaluation approach might give some recommendations for an improvement of the air quality monitoring systems. Copyright © 2004 John Wiley & Sons, Ltd. [source] Semiparametric approaches to flow normalization and source apportionment of substance transport in riversENVIRONMETRICS, Issue 3 2001Per Stålnacke Abstract Statistical analysis of relationships between time series of data exhibiting seasonal variation is often of great interest in environmental monitoring and assessment. The present study focused on regression models with time-varying intercept and slope parameters. In particular, we derived and tested semiparametric models in which rapid interannual and interseasonal variation in the intercept were penalized in the search for a model that combined a good fit to data with smoothly varying parameters. Furthermore, we developed a software package for efficient estimation of the parameters of such models. Test runs on time series of runoff data and riverine loads of nutrients and chloride in the Rhine River showed that the proposed smoothing methods were particularly useful for analysis of time-varying linear relationships between time series of data with both seasonal variation and temporal trends. The predictivity of the semiparametric models was superior to that of conventional parametric models. In addition, normalization of observed annual loads to mean or minimum runoff produced smooth curves that provided convincing evidence of human impact on water quality. Copyright © 2001 John Wiley & Sons, Ltd. [source] Redundant role for Zap70 in B cell development and activationEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 6 2008Farnaz Fallah-Arani Dr. Abstract Expression of the Syk family tyrosine kinase Zap70 is strongly correlated with poor clinical outcome in chronic lymphocytic leukemia, the most common human leukemia characterized by B cell accumulation. The expression of Zap70 may reflect the specific cell of origin of the tumor or may contribute to pathology. Thus, the normal role of Zap70 in B cell physiology is of great interest. While initial studies reported that Zap70 expression in the mouse was limited to T and NK cells, more recent work has shown expression in early B cell progenitors and in splenic B cells, suggesting that the kinase may play a role in the development or activation of B cells. In this study, we show that Zap70 is expressed in all developing subsets of B cells as well as in recirculating B cells, marginal zone B cells and peritoneal B1 cells. Analysis of Zap70-deficient mice shows no unique role for Zap70 in either the development of B cells or in their in vitro and in vivo activation. However, we show that Zap70 can rescue the defective positive selection of immature B cells into the recirculating pool in Syk-deficient mice, demonstrating functional redundancy between these two kinases. [source] Inorganic Analogues of GrapheneEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 27 2010C. N. R. Rao Abstract The discovery of graphene has aroused great interest in the properties and phenomena exhibited by two-dimensional inorganic materials, especially when they comprise only a single, two or a few layers. Graphene-like MoS2 and WS2 have been prepared by chemical methods, and the materials have been characterized by electron microscopy, atomic force microscopy (AFM) and other methods. Boron nitride analogues of graphene have been obtained by a simple chemical procedure starting with boric acid and urea and have been characterized by various techniques that include surface area measurements. A new layered material with the composition BCN possessing a few layers and a large surface area discovered recently exhibits a large uptake of CO2. [source] Iron(III) Chelation: Tuning of the pH Dependence by Mixed LigandsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 14 2003Anne-Marie Albrecht-Gary Abstract The iron(III) chelating properties of two heteropodands with 8-hydroxyquinoline and catechol binding groups were examined and compared to those of the corresponding homopodal analogues, O-TRENSOX and TRENCAMS. Like the parent homopodands, the two heteropodands are based on the TREN scaffold and the chelating units are connected by amide groups, TRENSOX2CAMS having two 8-hydroxyquinoline and one catechol arms and TRENSOXCAMS2 one 8-hydroxyquinoline and two catechol moieties. The aqueous coordination chemistry of these ligands was examined by potentiometric and spectrophotometric methods in combination with 1H NMR spectroscopy. The respective pFeIII values showed a cooperative effect of the mixed chelating units. Moreover, the pFeIII dependence on pH showed that the mixed ligands exhibit a higher complexing ability than the parent ligands over the pH range 5,9 which is of biological relevance. This result could be of great interest for medical applications. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] The relationship between baseline value and its change: problems in categorization and the proposal of a new methodEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 4 2005Yu-Kang Tu Oral health researchers have shown great interest in the relationship between the initial status of diseases and subsequent changes following treatment. Two main approaches have been adopted to provide evidence of a positive association between baseline values and their changes following treatment. One approach is to use correlation or regression to test the relationship between baseline measurements and subsequent change (correlation/regression approach). The second approach is to categorize the lesions into subgroups, according to threshold values, and subsequently compare the treatment effects across the two (or more) subgroups (categorization approach). However, the correlation/regression approach suffers a methodological weakness known as mathematical coupling. Consequently, the statistical procedure of testing the null hypothesis becomes inappropriate. Categorization seems to avoid the problem of mathematical coupling, although it still suffers regression to the mean. We show, first, how the appropriate null hypothesis may be established to analyze the relationship between baseline values and change in the correlation approach and, second, we use computer simulations to investigate the impact of regression to the mean on the significance testing of the differences in the average treatment effects (or average baseline values) in the categorization approach. Data available from previous literature are reanalyzed by testing the appropriate null hypotheses and the results are compared to those from testing the usual (incorrect) null hypothesis. The results indicate that both the correlation and categorization approaches can give rise to misleading conclusions and that more appropriate methods, such as Oldham's method and our new approach of deriving the correct null hypothesis, should be adopted. [source] Impact of Recrystallization Defects on the High Temperature Strength of PM 3030ADVANCED ENGINEERING MATERIALS, Issue 1-2 2009Michel NganbeArticle first published online: 19 FEB 200 The paper focuses on the impact of recrystallization defects on material strength as well as potential optimizations of material properties and manufacturing process. Therefore, it can be of great interest for materials research and development, production and quality control in industry. [source] CLIMATIC AND TEMPORAL EFFECTS ON THE EXPRESSION OF SECONDARY SEXUAL CHARACTERS: GENETIC AND ENVIRONMENTAL COMPONENTSEVOLUTION, Issue 3 2004Dany Garant Abstract Despite great interest in sexual selection, relatively little is known in detail about the genetic and environmental determinants of secondary sexual characters in natural populations. Such information is important for determining the way in which populations may respond to sexual selection. We report analyses of genetic and large-scale environmental components of phenotypic variation of two secondary sexual plumage characters (forehead and wing patch size) in the collared flycatcher Ficedula albicollis over a 22-year period. We found significant heritability for both characters but little genetic covariance between the two. We found a positive association between forehead patch size and a large-scale climatic index, the North Atlantic Oscillation (NAO) index, but not for wing patch. This pattern was observed in both cross-sectional and longitudinal data suggesting that the population response to NAO index can be explained as the result of phenotypic plasticity. Heritability of forehead patch size for old males, calculated under favorable conditions (NAO index median), was greater than that under unfavorable conditions (NAO index < median). These changes occurred because there were opposing changes in additive genetic variance (VA) and residual variance (VR) under favorable and unfavorable conditions, with VA increasing and VR decreasing in good environments. However, no such effect was detected for young birds, or for wing patch size in either age class. In addition to these environmental effects on both phenotypic and genetic variances, we found evidence for a significant decrease of forehead patch size over time in older birds. This change appears to be caused by a change in the sign of viability selection on forehead patch size, which is associated with a decline in the breeding value of multiple breeders. Our data thus reveal complex patterns of environmental influence on the expression of secondary sexual characters, which may have important implications for understanding selection and evolution of these characters. [source] Human evolution at the Matuyama-Brunhes boundaryEVOLUTIONARY ANTHROPOLOGY, Issue 1 2004Article first published online: 12 FEB 200, Giorgio Manzi Abstract The cranial morphology of fossil hominids between the end of the Early Pleistocene and the beginning of the Middle Pleistocene provides crucial evidence to understand the distribution in time and space of the genus Homo. This evidence is critical for evaluating the competing models regarding diversity within our genus. The debate focuses on two alternative hypotheses, one basically anagenetic and the other cladogenetic. The first suggests that morphological change is so diffused, slow, and steady that it is meaningless to apply species names to segments of a single lineage. The second is that the morphological variation observed in the fossil record can best be described as a number of distinct species that are not connected in a linear ancestor-descendant sequence. Today much more fossil evidence is available than was in the past to test these alternative hypotheses, as well as intermediate variants. Special attention must be paid to Africa because this is the most probable continental homeland for both the origin of the genus Homo (around 2.5,2 Ma),1 as well as the site, two million or so years later, of the emergence of the species H. sapiens.2 However, the African fossil record is very poorly represented between 1 Ma and 600 ka. Europe furnishes recent discoveries in this time range around the Matuyama-Brunhes chron boundary (780,000 years ago), a period for which, at present, we have no noteworthy fossil evidence in Africa or the Levant. Two penecontemporaneous sources of European fossil evidence, the Ceprano calvaria (Italy)3 and the TD6 fossil assemblage of Atapuerca (Spain)4 are thus of great interest for testing hypotheses about human evolution in the fundamental time span bracketed between the late Early and the Middle Pleistocene. This paper is based on a phenetic approach to cranial variation aimed at reviewing the Early-to-Middle Pleistocene trajectories of human evolution. The focus of the paper is on neither the origin nor the end of the story of the genus Homo, but rather its chronological and phylogenetic core. Elucidation of the evolutionary events that happened around 780 ka during the transition from the Early to Middle Pleistocene is one of the new frontiers for human paleontology, and is critical for understanding the processes that ultimately led to the origin of H. sapiens. [source] Cleavage fracture of RPV steel following warm pre-stressing: micromechanical analysis and interpretation through a new modelFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 9-10 2006S. R. BORDET ABSTRACT In this paper, the warm pre-stress (WPS) effect on the cleavage fracture of an 18MND5 (A533B) RPV steel is investigated. This effect, which describes the effective enhancement of the cleavage fracture toughness at low temperature following a prior loading at high temperature, has received great interest in light of its significance in the integrity assessment of structures, such as nuclear pressure vessels, subjected to thermal transients. Several loading cycles between room temperature (RT) and ,150 °C are considered: Load-Unload-Cool-Fracture (LUCF), Load-Cool-Fracture (LCF) and Load-Cool with Increasing K-Fracture (LCIKF). All experiments complied with the conservative principle, which states that no fracture will occur if the applied stress intensity factor (SIF) decreases (or is held constant) while the temperature at the crack-tip decreases, even if the fracture toughness of the virgin material is exceeded. The experimental results indicate that an effective WPS effect is present even at small pre-load (Kwps= 40 MPa,m), and that a minimum critical slope (,,K/,T) in the LCIKF cycle has to be exceeded to induce cleavage fracture between RT and ,150 °C. Numerical modelling was performed using mixed isotropic and kinematic hardening laws identified on notched tensile (NT) specimens, tested in tension to large strains (up to 40%), followed by large compressive strains. Detailed microstructural investigations on compact tensile (CT) and NT fracture test specimens were performed so as to determine the nature of the cleavage initiation sites, as well as the local mechanical conditions at fracture. Based on this local information, a new cleavage model was calibrated and applied to predict the probability of cleavage fracture after WPS: it is shown that the predictions are in good agreement with the experimental results. [source] The adaptive response of anaerobically grown Saccharomyces cerevisiae to hydrogen peroxide is mediated by the Yap1 and Skn7 transcription factorsFEMS YEAST RESEARCH, Issue 8 2008Anthony G. Beckhouse Abstract The molecular mechanisms involved in the ability of cells to adapt and respond to differing oxygen tensions are of great interest to the pharmaceutical, medical and fermentation industries. The transcriptional profiles reported in previous studies of cells grown under anaerobic, aerobic and dynamic growth conditions have shown significantly altered responses including induction of genes regulated by the oxidative stress transcription factor Yap1p when oxygen was present. The present study investigated the phenotypic changes that occur in cells when shifted from anaerobic to aerobic growth conditions and it was found through mutant analyses that the elevated activity of Yap1p during the shift was mediated by the phospholipid hydroperoxide-sensing protein encoded by GPX3. Cell viability and growth rate were unaffected even though anaerobically grown cells were found to be hypersensitive to low doses of the oxidative stress-inducing compound hydrogen peroxide (H2O2). Adaptation to H2O2 treatment was demonstrated to occur when anaerobically grown wild-type cells were aerated for a short time that was reliant on the Yap1p and Skn7p transcription factors. [source] The Hill equation: a review of its capabilities in pharmacological modellingFUNDAMENTAL & CLINICAL PHARMACOLOGY, Issue 6 2008Sylvain Goutelle Abstract The Hill equation was first introduced by A.V. Hill to describe the equilibrium relationship between oxygen tension and the saturation of haemoglobin. In pharmacology, the Hill equation has been extensively used to analyse quantitative drug,receptor relationships. Many pharmacokinetic,pharmacodynamic models have used the Hill equation to describe nonlinear drug dose,response relationships. Although the Hill equation is widely used, its many properties are not all well known. This article aims at reviewing the various properties of the Hill equation. The descriptive aspects of the Hill equation, in particular mathematical and graphical properties, are examined, and related to Hill's original work. The mechanistic aspect of the Hill equation, involving a strong connection with the Guldberg and Waage law of mass action, is also described. Finally, a probabilistic view of the Hill equation is examined. Here, we provide some new calculation results, such as Fisher information and Shannon entropy, and we introduce multivariate probabilistic Hill equations. The main features and potential applications of this probabilistic approach are also discussed. Thus, within the same formalism, the Hill equation has many different properties which can be of great interest for those interested in mathematical modelling in pharmacology and biosciences. [source] Amphiregulin is a factor for resistance of glioma cells to cannabinoid-induced apoptosisGLIA, Issue 13 2009Mar Lorente Abstract Gliomas, one of the most malignant forms of cancer, exhibit high resistance to conventional therapies. Identification of the molecular mechanisms responsible for this resistance is therefore of great interest to improve the efficacy of the treatments against these tumors. ,9-Tetrahydrocannabinol (THC), the major active ingredient of marijuana, and other cannabinoids inhibit tumor growth in animal models of cancer, including glioma, an effect that relies, at least in part, on the ability of these compounds to induce apoptosis of tumor cells. By analyzing the gene expression profile of two sub-clones of C6 glioma cells with different sensitivity to cannabinoid-induced apoptosis, we found a subset of genes with a marked differential expression in the two sub-clones. Furthermore, we identified the epidermal growth factor receptor ligand amphiregulin as a candidate factor to mediate the resistance of glioma cells to cannabinoid treatment. Amphiregulin was highly overexpressed in the cannabinoid-resistant cell line, both in culture and in tumor xenografts. Moreover, in vivo silencing of amphiregulin rendered the resistant tumors xenografts sensitive to cannabinoid antitumoral action. Amphiregulin expression was associated with increased extracellular signal-regulated kinase (ERK) activation, which mediated the resistance to THC by blunting the expression of p8 and TRB3,two genes involved in cannabinoid-induced apoptosis of glioma cells. Our findings therefore identify Amphirregulin as a factor for resistance of glioma cells to THC-induced apoptosis and contribute to unraveling the molecular bases underlying the emerging notion that targeted inhibition of the EGFR pathway can improve the efficacy of antitumoral therapies. © 2009 Wiley-Liss, Inc. [source] Heparinized Magnetic Nanoparticles: In-Vitro Assessment for Biomedical Applications,ADVANCED FUNCTIONAL MATERIALS, Issue 13 2006C. Wuang Abstract Superparamagnetic magnetite nanoparticles are of great interest owing to their numerous existing and potential biomedical applications. In this study, superparamagnetic magnetite nanoparticles with average diameters of 6,8,nm have been prepared and surface-functionalized with poly(N -isopropylacrylamide) (poly(NIPAAM)) via a surface-initiated atom-transfer radical polymerization, followed by immobilization of heparin. The success of the various surface-functionalization steps has been ascertained using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The rate of internalization of the as-synthesized and surface-functionalized magnetite nanoparticles by mouse macrophage cells has been investigated. The nanoparticle internalization into the macrophages has been visualized using optical microscopy and quantified by inductively coupled plasma spectroscopy. The effectiveness of the heparinized nanoparticles in preventing thrombosis has been determined using the plasma recalcification time. The results indicate that the above-mentioned surface modifications of the magnetite nanoparticles are effective in delaying phagocytosis and preventing blood clotting in vitro. Such properties can be expected to enable their use in biomedical applications. [source] | |||||||||||||||||||||||||||||||||||||||||||||||||