Associating polymer-surfactant systems

Some recent illustrations of the phase behavior of polymer-amphiphile systems in solution are presented. Surfactant-polymer association is demonstrated for various amphiphilic synthetic and biological polymers both on a macroscopic and on a single molecular level

Fragment-Based Design of Mycobacterium tuberculosis InhA Inhibitors.

Tuberculosis (TB) remains a leading cause of mortality among infectious diseases worldwide. InhA has been the focus of numerous drug discovery efforts as this is the target of the first line pro-drug isoniazid. However, with resistance to this drug becoming more common, the aim has been to find new clinical candidates that directly inhibit this enzyme and that do not require activation by the catalase peroxidase KatG, thus circumventing the majority of the resistance mechanisms. In this work, the screening and validation of a fragment library are described, and the development of the fragment hits using a fragment growing strategy was employed, which led to the development of InhA inhibitors with affinities of up to 250 nM

Estimation of the solubility parameters of model plant surfaces and agrochemicals: a valuable tool for understanding plant surface interactions

Background Most aerial plant parts are covered with a hydrophobic lipid-rich cuticle, which is the interface between the plant organs and the surrounding environment. Plant surfaces may have a high degree of hydrophobicity because of the combined effects of surface chemistry and roughness. The physical and chemical complexity of the plant cuticle limits the development of models that explain its internal structure and interactions with surface-applied agrochemicals. In this article we introduce a thermodynamic method for estimating the solubilities of model plant surface constituents and relating them to the effects of agrochemicals. Results Following the van Krevelen and Hoftyzer method, we calculated the solubility parameters of three model plant species and eight compounds that differ in hydrophobicity and polarity. In addition, intact tissues were examined by scanning electron microscopy and the surface free energy, polarity, solubility parameter and work of adhesion of each were calculated from contact angle measurements of three liquids with different polarities. By comparing the affinities between plant surface constituents and agrochemicals derived from (a) theoretical calculations and (b) contact angle measurements we were able to distinguish the physical effect of surface roughness from the effect of the chemical nature of the epicuticular waxes. A solubility parameter model for plant surfaces is proposed on the basis of an increasing gradient from the cuticular surface towards the underlying cell wall. Conclusions The procedure enabled us to predict the interactions among agrochemicals, plant surfaces, and cuticular and cell wall components, and promises to be a useful tool for improving our understanding of biological surface interactions

Axion Protection from Flavor

The QCD axion fails to solve the strong CP problem unless all explicit PQ violating, Planck-suppressed, dimension n<10 operators are forbidden or have exponentially small coefficients. We show that all theories with a QCD axion contain an irreducible source of explicit PQ violation which is proportional to the determinant of the Yukawa interaction matrix of colored fermions. Generically, this contribution is of low operator dimension and will drastically destabilize the axion potential, so its suppression is a necessary condition for solving the strong CP problem. We propose a mechanism whereby the PQ symmetry is kept exact up to n=12 with the help of the very same flavor symmetries which generate the hierarchical quark masses and mixings of the SM. This "axion flavor protection" is straightforwardly realized in theories which employ radiative fermion mass generation and grand unification. A universal feature of this construction is that the heavy quark Yukawa couplings are generated at the PQ breaking scale.Comment: 16 pages, 2 figure

A new thiocyanoacetamide (2-cyano-2-p-nitrophenyl-N-benzylthioamide) reduces doxorubicin-induced in vitro toxicity in Sertoli cells by decreasing apoptosis and autophagy

Despite conflicting data on doxorubicin (DOX) reproductive toxicity, its chemotherapeutic potential sustains its use to treat different types of cancer. This work was designed to study the protective effect of a newly synthesized thiocyanoacetamide (TA), in comparison with selenium (Se), against doxorubicin-induced in vitro toxicity in rat Sertoli cells (SCs). DOX was administered alone or in combination with Se or TA. The possible protective role of increased concentrations of TA (0.25, 0.5 and 1 mM) or Se (12, 25 and 50 mu M) on SCs was tested against 1 mu M of DOX. From this screening, only the least toxic doses of TA and Se were used for further analysis. DOX cytotoxicity, as well as its impact on SCs viability, mitochondria) membrane potential (Delta Psi(m)), oxidative stress biomarkers, apoptosis and autophagy were assessed. Our results showed that DOX exerted its cytotoxic effect through a significant increase in cell death. DOX-mediated cell death was not related to autophagy nor to an overproduction of reactive oxygen species. It was rather due to apoptosis, as shown by the increased number of apoptotic cells and increased activity of caspase-3, or due to necrosis, as shown by the increase in lactate dehydrogenase (LDH) extracellular activity. Still, Bax and Bcl-2 protein expression levels, as well as Delta Psi(m) were not altered by the different treatments. Some individual doses of Se or TA induced a significant toxicity in SCs, however, when combined with DOX, there was a decrease in cell death, LDH extracellular activity, number of apoptotic cells and caspase-3 activity. Overall, our results indicate that DOX-mediated apoptosis in cultured SCs can possibly be averted through its association with specific doses of Se or TA. Nevertheless, TA showed a higher efficiency than Se in reducing DOX-induced toxicity in SCs by decreasing not only apoptosis, but also necrosis and autophagy. (C) 2019 Elsevier Inc. All rights reserved

Mumps epidemic in Portugal despite high vaccine coverage : preliminary report

A measles, mumps, and rubella (MMR) trivalent vaccine was added to Portugal’s National Immunisation Programme (NIP) in 1987. All vaccines are given at health centres, free of charge, but an epidemic of mumps began in 1995, firstly in northern Portugal and has now spread to other areas. Initially, only one dose of MMR vaccine at the age of 15 months was recommended. In 1990 a second dose at the age of 11 to 13 years was added. Portugal was one of the first countries in Europe to advocate this policy

Atypical disengagement from faces and its modulation by the control of eye fixation in children with Autism Spectrum Disorder

By using the gap overlap task, we investigated disengagement from faces and objects in children (9–17 years old) with and without autism spectrum disorder (ASD) and its neurophysiological correlates. In typically developing (TD) children, faces elicited larger gap effect, an index of attentional engagement, and larger saccade-related event-related potentials (ERPs), compared to objects. In children with ASD, by contrast, neither gap effect nor ERPs differ between faces and objects. Follow-up experiments demonstrated that instructed fixation on the eyes induces larger gap effect for faces in children with ASD, whereas instructed fixation on the mouth can disrupt larger gap effect in TD children. These results suggest a critical role of eye fixation on attentional engagement to faces in both groups

The influence of ethylene and ethylene modulators on shoot organogenesis in tomato

[EN] The influence of ethylene and ethylene modulators on the in vitro organogenesis of tomato was studied using a highly regenerating accession of the wild tomato Solanum pennellii and an F1 plant resulting from a cross between Solanum pennellii and Solanum lycopersicum cv. Anl27, which is known to have a low regeneration frequency. Four ethylene-modulating compounds, each at four levels, were used, namely: cobalt chloride (CoCl 2), which inhibits the production of ethylene; AgNO 3 (SN), which inhibits ethylene action; and Ethephon and the precursor 1-aminocyclopropane-1-carboxylic acid (ACC), which both promote ethylene synthesis. Leaf explants of each genotype were incubated on shoot induction medium supplemented with each of these compounds at 0, 10 or 15 days following bud induction. The results obtained in our assays indicate that ethylene has a significant influence on tomato organogenesis. Concentrations of ethylene lower than the optimum (according to genotype) at the beginning of the culture may decrease the percentage of explants with buds (B), produce a delay in their appearance, or indeed inhibit bud formation. This was observed in S. pennellii and the F1 explants cultured on media with SN (5.8-58.0 ¿M) as well as in the F1 explants cultured on medium with 21.0 ¿M CoCl 2. The percentage of explants with shoots (R) and the mean number of shoots per explant with shoots (PR) also diminished in media that contained SN. Shoots isolated from these explants were less developed compared to those isolated from control explants. On the other hand, ethylene supplementation may contribute to enhancing shoot development. The number of isolable shoots from S. pennellii explants doubled in media with ACC (9.8-98.0 ¿M). Shoots isolated from explants treated with ethylene releasing compounds showed a higher number of nodes when ACC and Ethephon were added at 10 days (in F1 explants) or at 15 days (in S. pennellii) after the beginning of culture. Thus, the importance of studying not only the concentration but also the timing of the application of regulators when developing regeneration protocols has been made manifest. An excess of ethylene supplementation may produce an inhibitory effect, as was observed when using Ethephon (17.2-69.0 ¿M). These results show the involvement of ethylene in tomato organogenesis and lead us to believe that ethylene supplementation may contribute to enhancing regeneration and shoot development in tomato. © 2012 Springer Science+Business Media B.V.Carlos Trujillo has a predoctoral fellowship from the Spanish 'Ministerio de Educacion y Ciencia'. This work has been funded by Universitat Politecnica de Valencia (PAID 05-10). The technical assistance of N. Palacios and the revision of the manuscript's English by J. Bergen are gratefully acknowledged.Trujillo Moya, C.; Gisbert Domenech, MC. (2012). The influence of ethylene and ethylene modulators on shoot organogenesis in tomato. Plant Cell, Tissue and Organ Culture. 111(1):141-148. https://doi.org/10.1007/s11240-012-0168-zS1411481111Abeles FB, Morgan PW, Saltveit ME (1992) Ethylene in plant biology. Academic Press, San DiegoBhatia P, Ashwath N, Senaratna T, David M (2004) Tissue culture studies of tomato (Lycopersicon esculentum). Plant Cell Tiss Org Cult 78:1–21Bhatia P, Ashwath N, Midmore DJ (2005) Effects of genotype, explant orientation, and wounding on shoot regeneration in tomato. In Vitro Cell Dev Biol-Plant 41:457–464Biddington NL (1992) The Influence of ethylene in plant-tissue culture. Plant Growth Regul 11:173–187Brown DC, Thorpe TA (1995) Crop improvement through tissue culture. World J Microbiol Biotechnol 11(4):409–415Chraibi KMB, Latche A, Roustan JP, Fallot J (1991) Stimulation of shoot regeneration from cotyledons of Helianthus annuus by the ethylene inhibitors,silver and cobalt. Plant Cell Rep 10:204–207Devi R, Dhaliwal MS, Kaur A, Gosal SS (2008) Effect of growth regulators on in vitro morphogenic response of tomato. Indian J Biotechnol 7:526–530Dias LLC, Santa-Catarina C, Ribeiro DM, Barros RS, Floh EIS, Otoni WC (2009) Ethylene and polyamine production patterns during in vitro shoot organogenesis of two passion fruit species as affected by polyamines and their inhibitor. Plant Cell Tiss Org Cult 99:199–208Dimasi-Theriou K, Economou AS (1995) Ethylene enhances shoot formation in cultures of the peach rootstock GF-677 (Prunus persica × P. amygdalus). Plant Cell Rep 15:87–90Gisbert C, Arrillaga I, Roig LA, Moreno V (1999) Adquisition of a collection of Lycopersicon pennellii (Corr. D’Arcy) transgenic plants with uidA and nptII marker genes. 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Plant Cell Tiss Org Cult 51:75–78Moshkov IE, Novikova GV, Hall MA, George EF (2008) Plant Growth Regulators III: ethylene. In: George EF, Hall MA, Klerk G-JD (eds) Plant Propaga-tion by Tissue Culture, vol 1. 3rd edn. Springer, The Netherlands, pp 239–248Murashige T, Skoog F (1962) A revised medium for rapid growth and bioassays with tobacco tissue cultures. Physiol Plant 15:473–497Osman MG, Khalafalla MM (2010) Promotion of in vitro shoot formation from shoot tip of tomato (Lycopersicon esculentum Mill. cv. Omdurman) by ethylene inhibitors. Int J Curr Res 4:82–86Ptak A, El Tahchy A, Wyzgolik G, Henry M, Laurain-Mattar D (2010) Effects of ethylene on somatic embryogenesis and galantamine content in Leucojum aestivum L. cultures. Plant Cell Tiss Org Cult 102:61–67Pua EC, Sim GE, Chi GL, Kong LF (1996) Synergistic effects of ethylene inhibitors and putrescine on shoot regeneration from hypocotyl explants of Chinese radish (Raphanus sativus L. var. longipinnatus Bailey) in vitro. 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Avaliação da resistência ao cisalhamento da união entre duas ligas a base de CoCr e uma cerâmica

INTRODUCTION: Based on the importance of the integrity of the metal/ceramic interface, the purpose of this work was to evaluate the shear bond strength of the metal-ceramic union of two Co-Cr alloys (Wirobond C, Bego; Remanium 2000, Dentaurum) combined with Omega 900 ceramic (Vita Zahnfabrik). MATERIAL and METHOD: Eleven cylindrical matrixes were made for each alloy, and the metallic portion was obtained with the lost wax casting technique with standardized waxing of 4mm of height and of 4mm of diameter. The ceramic was applied according to the manufacturer’s recommendations with the aid of a teflon matrix that allowed its dimension to be standardized in the same size as the metallic portion. The specimens were submitted to the shear bond test in an universal testing machine (EMIC), with the aid of a device developed for such intention, and constant speed of 0.5mm/min. RESULTS and CONCLUSIONS: The mean resistance was 48.387MPa for Wirobond C alloy, with standard deviation of 17.718, and 55.956MPa for Remanium 2000, with standard deviation of 17.198. No statistically significant difference was observed between the shear strength of the two metal-ceramic alloys. ______________________________________________________________________________________________________________ RESUMOINTRODUÇÃO: Baseados na importância da integridade da interface metal-cerâmica, este trabalho tem como objetivo avaliar a resistência ao cisalhamento da união metal-cerâmica de duas ligas de Co-Cr (Wirobond C, Bego; Remanium 2000, Dentaurum) combinadas com a cerâmica Omega 900 (Vita Zahnfabrik). MATERIAIS E MÉTODOS: Foram confeccionados 11 corpos-de-prova cilíndricos para cada liga utilizada, sendo que a porção metálica foi obtida por fundição pela técnica da cera perdida, através de enceramentos padronizados com 4mm de altura por 4mm de diâmetro. A aplicação da cerâmica foi realizada segundo recomendações do fabricante, com auxílio de uma matriz de teflon que permitia sua padronização com as mesmas dimensões da porção metálica. Os corpos-de-prova foram submetidos ao ensaio de resistência ao cisalhamento em máquina de ensaios universal (EMIC), com auxílio de dispositivo desenvolvido para tal propósito, sob velocidade constante de 0,5mm/ min. RESULTADOS E CONCLUSÕES: As médias de resistência obtidas foram 48,387 MPa para a liga Wirobond C, com desvio padrão de 17,718, e 55,956 MPa para a Remanium 2000, com desvio padrão de 17,198. Após análise de variância foi possível observar que não há diferença estatisticamente significante entre os valores de resistência ao cisalhamento das duas ligas metalocerâmicas

Plant species richness regulates soil respiration through changes in productivity

Soil respiration is an important pathway of the C cycle. However, it is still poorly understood how changes in plant community diversity can affect this ecosystem process. Here we used a long-term experiment consisting of a gradient of grassland plant species richness to test for effects of diversity on soil respiration. We hypothesized that plant diversity could affect soil respiration in two ways. On the one hand, more diverse plant communities have been shown to promote plant productivity, which could increase soil respiration. On the other hand, the nutrient concentration in the biomass produced has been shown to decrease with diversity, which could counteract the production-induced increase in soil respiration. Our results clearly show that soil respiration increased with species richness. Detailed analysis revealed that this effect was not due to differences in species composition. In general, soil respiration in mixtures was higher than would be expected from the monocultures. Path analysis revealed that species richness predominantly regulates soil respiration through changes in productivity. No evidence supporting the hypothesized negative effect of lower N concentration on soil respiration was found. We conclude that shifts in productivity are the main mechanism by which changes in plant diversity may affect soil respiration