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排序方式: 共有816条查询结果,搜索用时 15 毫秒
31.
32.
Leite ES Santana SR Hünenberger PH Freitas LC Longo RL 《Journal of molecular modeling》2007,13(9):1017-1025
The relative stabilities of the alkali [M ⊂ 222]+ cryptates (M = Na, K, Rb and Cs) in the gas phase and in solution (80:20 v/v methanol:water mixture) at 298 K, are computed
using a combination of ab initio quantum-chemical calculations (HF/6-31G and MP2/6-31+G*//HF/6-31+G*) and explicit-solvent
Monte Carlo free-energy simulations. The results suggest that the relative stabilities of the cryptates in solution are due
to a combination of steric effects (compression of large ions within the cryptand cavity), electronic effects (delocalization
of the ionic charge onto the cryptand atoms) and solvent effects (dominantly the ionic dessolvation penalty). Thus, the relative
stabilities in solution cannot be rationalized solely on the basis of a simple match or mismatch between the ionic radius
and the cryptand cavity size as has been suggested previously. For example, although the [K ⊂ 222]+ cryptate is found to be the most stable in solution, in agreement with experimental data, it is the [Na ⊂ 222]+ cryptate that is the most stable in the gas phase. The present results provide further support to the notion that the solvent
in which supramolecules are dissolved plays a key role in modulating molecular recognition processes.
Figure Alkali cryptates [M ⊂ 222]+ (M = Na, K, Rb and Cs) relative stabilities in gas and methanol:water solution: solvent effects
and molecular recognition
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
33.
Pereira LA Báo SN Barbosa MS da Silva JL Felipe MS de Santana JM Mendes-Giannini MJ de Almeida Soares CM 《FEMS yeast research》2007,7(8):1381-1388
Paracoccidioides brasiliensis is an important fungal pathogen. The disease it causes, paracoccidioidomycosis (PCM), ranges from localized pulmonary infection to systemic processes that endanger the life of the patient. Paracoccidioides brasiliensis adhesion to host tissues contributes to its virulence, but we know relatively little about molecules and the molecular mechanisms governing fungal adhesion to mammalian cells. Triosephosphate isomerase (TPI: EC 5.3.1.1) of P. brasiliensis (PbTPI) is a fungal antigen characterized by microsequencing of peptides. The protein, which is predominantly expressed in the yeast parasitic phase, localizes at the cell wall and in the cytoplasmic compartment. TPI and the respective polyclonal antibody produced against this protein inhibited the interaction of P. brasiliensis to in vitro cultured epithelial cells. TPI binds preferentially to laminin, as determined by peptide inhibition assays. Collectively, these results suggest that TPI is required for interactions between P. brasiliensis and extracellular matrix molecules such as laminin and that this interaction may play an important role in the fungal adherence and invasion of host cells. 相似文献
34.
Santos LC Ramos EA Gurgel CA de Santana EJ Dos Santos JN 《Journal of molecular histology》2007,38(3):201-205
Objective Dental granulomas (DGs) and radicular cysts (RCs) are chronic periapical lesions frequently involving the jaws. Langerhans
cells (LCs) are dendritic cells responsible for the presentation of antigens to T lymphocytes. This study examined the expression
of LCs in DG and RCs by immunohistochemical staining.
Study Design Eighteen cases of DGs and 26 cases of RCs were analyzed using anti-CD1a marker.
Results CD1a-labeled LCs were observed in 11.1% of DGs and in 69.2% of RCs, showing a significant correlation (P < 0.0001; Fisher’s test). In DGs, LCs were only observed in granulation tissue, showing discrete immunostaining density.
In RCs, LCs exhibited both a round and a dendritic shape in all epithelial layers. Although a correlation was observed between
immunostaining density and epithelial thickness, as well as between immunostaining and inflammatory intensity, the differences
were not significant in radicular cysts.
Conclusion Langerhans cells provide important insight into the immunopathogenesis of chronic periapical lesions. 相似文献
35.
de Jesus Santana Mayla Barbosa-Júnior Sebastião Martins Dias Lana Laene Lima Silva Lázara Aline Simões da Silva Givanildo Zildo Fortini Evandro Alexandre Batista Diego Silva Otoni Wagner Campos da Costa Netto Antônio Paulino Rocha Diego Ismael 《In vitro cellular & developmental biology. Plant》2022,58(6):865-875
In Vitro Cellular & Developmental Biology - Plant - The aim of this study was to establish a system of in vitro germination and propagation of Guazuma ulmifolia Lam. microcuttings (Malvaceae).... 相似文献
36.
Marco Savioli Lorenzo Antonelli Gianfranco Bocchinfuso Francesca Cavalieri Rita Cimino Emanuela Gatto Ernesto Placidi Julio Raul Fernandez Masso Hilda Garay Perez Hector Santana Maribel Guerra-Vallespi Mariano Venanzi 《Journal of peptide science》2022,28(1):e3356
Synthetic therapeutic peptides (STP) are intensively studied as new-generation drugs, characterized by high purity, biocompatibility, selectivity and stereochemical control. However, most of the studies are focussed on the bioactivity of STP without considering how the formulation actually used for therapy administration could alter the physico-chemical properties of the active principle. The aggregation properties of a 20-mer STP (Ac-His-Ala-Arg-Ile-Lys-D-Pro-Thr-Phe-Arg-Arg-D-Leu-Lys-Trp-Lys-Tyr-Lys-Gly-Lys-Phe-Trp-NH2), showing antitumor activity, were investigated by optical spectroscopy and atomic force microscopy imaging, as itself (CIGB552) and in its therapeutic formulation (CIGB552TF). It has found that the therapeutic formulation deeply affects the aggregation properties of the investigated peptide and the morphology of the aggregates formed on mica by deposition of CIGB552 and CIGB552TF millimolar solutions. Molecular dynamics simulations studied the first steps of CIGB552 aggregation under physiological ionic strength conditions (NaCl 150 mM), showing that peptide oligomers, from dimers to tetramers, are preferentially formed in this environment. Interestingly, cell viability assays performed on H-460 cell lines indicate a major antiproliferative activity of the peptide in its therapeutic formulation with respect to the peptide aqueous solution. 相似文献
37.
Kathryn E. Stanchak Jessica H. Arbour Sharlene E. Santana 《Evolution; international journal of organic evolution》2019,73(8):1591-1603
Neomorphic, membrane‐associated skeletal rods are found in disparate vertebrate lineages, but their evolution is poorly understood. Here we show that one of these elements—the calcar of bats (Chiroptera)—is a skeletal novelty that has anatomically diversified. Comparisons of evolutionary models of calcar length and corresponding disparity‐through‐time analyses indicate that the calcar diversified early in the evolutionary history of Chiroptera, as bats phylogenetically diversified after evolving the capacity for flight. This interspecific variation in calcar length and its relative proportion to tibia and forearm length is of functional relevance to flight‐related behaviors. We also find that the calcar varies in its tissue composition among bats, which might affect its response to mechanical loading. We confirm the presence of a synovial joint at the articulation between the calcar and the calcaneus in some species, which suggests the calcar has a kinematic functional role. Collectively, this functionally relevant variation suggests that adaptive advantages provided by the calcar led to its anatomical diversification. Our results demonstrate that novel skeletal additions can become integrated into vertebrate body plans and subsequently evolve into a variety of forms, potentially impacting clade diversification by expanding the available morphological space into which organisms can evolve. 相似文献
38.
Gerson N. Hernández-Acevedo Oscar H. López-Portales Darely Y. Gutiérrez-Reyna Erick Cuevas-Fernández Linda A. Kempis-Calanis Rosario G. Labastida-Conde Oscar B. Aguilar-Luviano Oscar Ramírez-Pliego Salvatore Spicuglia Bárbara Lino-Alfaro Alicia Chagolla-López Luis E. González-de la Vara María Angélica Santana 《Journal of cellular physiology》2019,234(10):18639-18652
The canonical Wnt signaling pathway is a master cell regulator involved in CD8+ T cell proliferation and differentiation. In human CD8+ T cells, this pathway induces differentiation into memory cells or a “stem cell memory like” population, which is preferentially present in cord blood. To better understand the role of canonical Wnt signals in neonatal or adult blood, we compared the proteins associated with β-catenin, in nonstimulated and Wnt3a-stimulated human neonatal and adult naive CD8+ T cells. Differentially recruited proteins established different complexes in adult and neonatal cells. In the former, β-catenin-associated proteins were linked to cell signaling and immunological functions, whereas those of neonates were linked to proliferation and metabolism. Wnt3a stimulation led to the recruitment and overexpression of Wnt11 in adult cells and Wnt5a in neonatal cells, suggesting a differential connexion with planar polarity and Wnt/Ca2+ noncanonical pathways, respectively. The chromatin immunoprecipitation polymerase chain reaction β-catenin was recruited to a higher level on the promoters of cell renewal genes in neonatal cells and of differentiation genes in those of adults. We found a preferential association of β-catenin with CBP in neonatal cells and with p300 in the adult samples, which could be involved in a higher self-renewal capacity of the neonatal cells and memory commitment in those of adults. Altogether, our results show that different proteins associated with β-catenin during Wnt3a activation mediate a differential response of neonatal and adult human CD8+ T cells. 相似文献
39.
Karoline Ceron Luiz Gustavo R. Oliveira‐Santos Camila S. Souza Daniel O. Mesquita Francis L. S. Caldas Andra C. Araujo Diego J. Santana 《Oikos》2019,128(11):1537-1548
Life on Earth is supported by an infinite number of interactions among organisms. Species interactions in these networks are influenced by latitude, evolutionary history and species traits. We performed a global‐scale literature analysis to build up a database of interactions between anuran communities and their preys, from a wide range of geographical areas, using a network approach. For this purpose, we compiled a total of 55 weighted anuran–prey interaction networks, 39 located in the tropics and 16 in temperate areas. We tested the influence of latitude, as well as anuran taxonomic, functional and phylogenetic richness on network metrics. We found that anuran–prey networks are not nested, exhibit low complementary specialization and modularity and high connectance when compared to other types of networks. The main effects on network metrics were related to latitude, followed by anuran taxonomic, functional and phylogenetic richness, a pattern similar to the emerging in mutualistic networks. Our study is the first integrated analysis of the structural patterns in anuran–prey antagonistic interaction networks in different parts of the world. We suggest that different processes, mediated mainly by latitude, are modeling the architecture of anuran–prey networks across the globe. 相似文献
40.
Adalgisa J. Pereira Irene M. Cardoso Hernane D. Araújo Felipe C. Santana Antonio P. S. Carneiro Steliane P. Coelho Franklin J. Pereira 《The Annals of applied biology》2019,174(1):14-19
Alternative methods of pest control can and should be encouraged, especially those that consider the reality of smallholder family farmers. Here, we evaluated the potential of Agave americana (agave) extracts for the control of the aphid Brevicoryne brassicae in cabbage (Brassica oleracea L. var acephala) in the field and laboratory. The field experiments consisted of the evaluation of the proportion of dead aphids on cabbage plants after application of agave extracts. In the field, agave mixed with cow milk caused mortality above 80% and was the most effective extract. Agave mixed with water and agave mixed with ethanol elicited mortality above 60%. In the laboratory, we evaluated the mortality of aphids after the application of different concentrations of aqueous agave extracts; the commercial insecticide deltamethrin was included as positive control. Evaluation took place at 3, 6, 12, 24, 48 and 72 hr after applying the treatment. As expected, deltamethrin was the most effective treatment. However, agave extract at concentrations of 0.750 and 0.500 g/mL caused >70% mortality 3 hr after application. We conclude that A. americana extracts decreased aphid populations and is a promising alternative to the commercial insecticide against aphids in cabbage. 相似文献