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61.
María Fernanda Manrique-de-la-Cuba Luis Leyva-Parra Diego Inostroza Prof. Badhin Gomez Dr. Alejandro Vásquez-Espinal Prof. Jorge Garza Dr. Osvaldo Yañez Prof. William Tiznado 《Chemphyschem》2021,22(10):906-910
We report the global minima structures of Li8Si8, Li10Si9, and Li12Si10 systems, in which silicon moieties maintain structural and chemical bonding characteristics similar to those of their building blocks: the aromatic clusters Td−Li4Si4 and C2v−Li6Si5. Electron counting rules, chemical bonding analysis, and magnetic response properties verify the silicon unit‘s aromaticity persistence. This study demonstrates the feasibility of assembling silicon-based nanostructures from aromatics clusters as building blocks. 相似文献
62.
Gabriela Pin-Zrate Fernanda Reyes-Riquelme Ma Beatriz Snchez-Monroy Mnica Velasco-Torrez Mariano Martínez-Vzquez Christian Adrian Crdenas-Monroy Beatriz Hernandez-Tllez Katia Jarquín-Yez Miguel ngel Herrera-Enríquez Andrs Eliú Castell-Rodríguez 《Molecules (Basel, Switzerland)》2022,27(4)
Dendritic cells are antigen-presenting cells, which identify and process pathogens to subsequently activate specific T lymphocytes. To regulate the immune responses, DCs have to mature by the recognition of TLR ligands, TNFα or IFNγ. These ligands have been used as adjuvants to activate DCs in situ or in vitro, with toxic effects. It has been shown that some molecules affect the immune system, e.g., Masticadienonic acid (MDA) and 3α-hydroxy masticadienoic acid (3α-OH MDA) triterpenes naturally occurring in several medicinal plants, since they activate the nitric oxide synthase in macrophages and induce T lymphocyte proliferation. The DCs maturation induced by MDA or 3a-OH MDA was determined by incubating these cells with MDA or 3α-OH MDA, and their phenotype was afterwards analyzed. The results showed that only 3α-OH MDA was able to induce DCs maturation. When mice with melanoma were inoculated with DCs/3α-OH MDA, a decreased tumor growth rate was observed along with an extended cell death area within tumors compared to mice treated with DCs incubated with MDA. In conclusion, it is proposed that 3α-OH MDA may be an immunostimulant molecule. Conversely, it is proposed that MDA may be a molecule with anti-inflammatory properties. 相似文献
63.
Eric Mayer-Santos Tatjana Maravic Allegra Comba Patricia Moreira Freitas Giovanna Bueno Marinho Claudia Mazzitelli Edoardo Mancuso Nicola Scotti Federica Florenzano Lorenzo Breschi Annalisa Mazzoni 《Molecules (Basel, Switzerland)》2022,27(5)
This study aimed to investigate matrix metalloproteinase (MMP) activity in human dentin using in-situ and gelatin zymography, after at-home and in-office bleaching, related to their clinical exposure times. Dentin specimens (n = 5) were treated with 35% hydrogen peroxide (50 min per session/4 sessions), 10% carbamide peroxide (180 min/21 sessions), or no treatment. All were subjected to in-situ zymography. Dentin slices were, subsequently, obtained, covered with fluorescein-conjugated gelatin, and examined with confocal laser-scanning microscopy. The fluorescence intensity was quantified and statistically analyzed using one-way ANOVA and Bonferroni tests (α = 0.05). Furthermore, gelatin zymography was performed on protein extracts obtained from dentin powder (N = 8 teeth), treated with hydrogen peroxide or carbamide peroxide, with different exposure times (10/50 min for hydrogen peroxide; 252/1260 min for carbamide peroxide). The results of the in-situ zymography showed no statistical differences between the bleached specimens and the control group, with a medium level of gelatinolytic activity expressed in the dentin tubules. The results of gelatin zymography showed an increased expression of pro-MMP-9 in carbamide peroxide groups. The expression of pro-MMP-2 decreased in all the experimental groups. The bleaching treatments performed on the enamel of sound teeth do not influence dentinal enzymatic activity. However, when unprotected dentin tissue is bleached, matrix metalloproteinases are more expressed, particularly when carbamide peroxide is used, proportional to the exposure time. 相似文献
64.
CaII Binding Regulates and Dominates the Reactivity of a Transition‐Metal‐Ion‐Dependent Diesterase from Mycobacterium tuberculosis 下载免费PDF全文
Dr. Marcelo M. Pedroso Prof. James A. Larrabee Dr. Fernanda Ely Shuhui E. Gwee Dr. Nataša Mitić Prof. David L. Ollis Prof. Lawrence R. Gahan Prof. Gerhard Schenk 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(3):999-1009
The diesterase Rv0805 from Mycobacterium tuberculosis is a dinuclear metallohydrolase that plays an important role in signal transduction by controlling the intracellular levels of cyclic nucleotides. As Rv0805 is essential for mycobacterial growth it is a promising new target for the development of chemotherapeutics to treat tuberculosis. The in vivo metal‐ion composition of Rv0805 is subject to debate. Here, we demonstrate that the active site accommodates two divalent transition metal ions with binding affinities ranging from approximately 50 nm for MnII to about 600 nm for ZnII. In contrast, the enzyme GpdQ from Enterobacter aerogenes, despite having a coordination sphere identical to that of Rv0805, binds only one metal ion in the absence of substrate, thus demonstrating the significance of the outer sphere to modulate metal‐ion binding and enzymatic reactivity. CaII also binds tightly to Rv0805 (Kd≈40 nm ), but kinetic, calorimetric, and spectroscopic data indicate that two CaII ions bind at a site different from the dinuclear transition‐metal‐ion binding site. CaII acts as an activator of the enzymatic activity but is able to promote the hydrolysis of substrates even in the absence of transition‐metal ions, thus providing an effective strategy for the regulation of the enzymatic activity. 相似文献
65.
I. T. L. Bresolin M. Borsoi-Ribeiro W. M. S. C. Tamashiro E. F. P. Augusto M. A. Vijayalakshmi S. M. A. Bueno 《Applied biochemistry and biotechnology》2010,160(7):2148-2165
Monoclonal antibodies (MAbs) have been used for therapies and some analytical procedures as highly purified molecules. Many
techniques have been applied and studied, focusing on monoclonal antibodies purification. In this study, an immobilized metal
affinity chromatography membrane was developed and evaluated for the purification of anti-TNP IgG1 mouse MAbs from cell culture supernatant after precipitation with a 50% saturated ammonium sulfate solution. The chelating
ligands iminodiacetic acid, carboxymethylated aspartic acid (CM-Asp), nitrilotriacetic acid, and tris (carboxymethyl) ethylenediamine
in agarose gels with immobilized Ni(II) and Zn(II) ions were compared for the adsorption and desorption of MAbs. The most
promising chelating ligand—CM-Asp—was then coupled to poly(ethylene vinyl alcohol) (PEVA) hollow fiber membranes. According
to SDS-PAGE and ELISA analyses, a higher selectivity and a purification factor of 85.9 (fraction eluted at 500 mM Tris) were
obtained for IgG1 using PEVA-CM-Asp-Zn(II). The anti-TNP MAb could be eluted under mild pH conditions causing no loss of antigen binding capacity. 相似文献
66.
Francisco J. Prado‐Prado Florencio M. Ubeira Fernanda Borges Humberto González‐Díaz 《Journal of computational chemistry》2010,31(1):164-173
In the previous work, we reported a multitarget Quantitative Structure‐Activity Relationship (mt‐QSAR) model to predict drug activity against different fungal species. This mt‐QSAR allowed us to construct a drug–drug multispecies Complex Network (msCN) to investigate drug–drug similarity (González‐Díaz and Prado‐Prado, J Comput Chem 2008, 29, 656). However, important methodological points remained unclear, such as follows: (1) the accuracy of the methods when applied to other problems; (2) the effect of the distance type used to construct the msCN; (3) how to perform the inverse procedure to study species–species similarity with multidrug resistance CNs (mdrCN); and (4) the implications and necessary steps to perform a substructural Triadic Census Analysis (TCA) of the msCN. To continue the present series with other important problem, we developed here a mt‐QSAR model for more than 700 drugs tested in the literature against different parasites (predicting antiparasitic drugs). The data were processed by Linear Discriminate Analysis (LDA) and the model classifies correctly 93.62% (1160 out of 1239 cases) in training. The model validation was carried out by means of external predicting series; the model classified 573 out of 607, that is, 94.4% of cases. Next, we carried out the first comparative study of the topology of six different drug–drug msCNs based on six different distances such as Euclidean, Chebychev, Manhattan, etc. Furthermore, we compared the selected drug–drug msCN and species–species mdsCN with random networks. We also introduced here the inverse methodology to construct species–species msCN based on a mt‐QSAR model. Last, we reported the first substructural analysis of drug–drug msCN using Triadic Census Analysis (TCA) algorithm. © 2009 Wiley Periodicals, Inc. J Comput Chem 2010 相似文献
67.
Fernanda Cipriano 《Communications in Mathematical Physics》1999,201(1):139-154
We construct surface type measures on the level sets for the renormalized energy, which is an invariant quantity for the two
dimensional periodic Euler flow, and prove the existence of weak solutions living on such level sets. Other classes of invariant
measures for the motion are also introduced.
Received: 3 December 1997 / Accepted: 20 August 1998 相似文献
68.
A Mueller-matrix imaging polarimeter was developed to measure spatially resolved polarization properties in the living human eye. The apparatus is a double-pass setup that incorporates two liquid-crystal variable retarders and a slow-scan CCD camera in the recording stage. Series of 16 images for the combinations of independent polarization states in the first and second passages were recorded for two experimental conditions: with the camera conjugated either with the retina or with the eye's pupil plane. Spatially resolved collections of Mueller matrices and the degree of polarization were calculated from those images for both retinal and pupil planes. 相似文献
69.
Maqueda M Gálvez A Bueno MM Sanchez-Barrena MJ González C Albert A Rico M Valdivia E 《Current protein & peptide science》2004,5(5):399-416
After the discovery of bacteriocin AS-48, a 70-residue cyclic peptide produced by Enterococcus faecalis subsp. liquefaciens, some naturally-occurring cyclic proteins from bacteria have been reported. AS-48 is encoded by the 68-kb pheromone-responsive plasmid pMB2, and the gene cluster involved in production and immunity has been identified and sequenced. This peptide exerts a bactericidal action on sensitive cells (most of the Gram-positive and some Gram-negative bacteria). Its target is the cytoplasmic membrane, in which it opens pores, leading to the dissipation of the proton motive force and cell death, a mechanism similar to that proposed for the action of defensins or, most generally, cationic antibacterial peptides. This fact, together with its remarkable stability and solubility over a wide pH range, suggest that this bacteriocin could be a good candidate as a natural food preservative. The amino acid composition of purified AS-48 shows the absence of modified or dehydrated residues, making it clearly different from lantibiotics. Bacteriocin AS-48 also differs from defensins in that it does not contain cysteines and consequently no disulfide bridges, which makes is high stability even more remarkable. Composition analysis of AS-48 shows a high proportion of basic to acidic amino acids, conferring to this peptide a strong basic character, with an isoelectric point close to 10.5. Determination of the AS-48 structural gene DNA sequence, together with the sequences of AS-48 protease digestion fragments and mass spectrometry determinations, allowed us to determine unambiguously the cyclic structure of the molecule, being the first example of a posttranslational modification in which a cyclic structure arises from a "head-to-tail" linkage. We have solved the three-dimensional structure of AS-48 in solution, and it consists of a globular arrangement of five alpha-helices enclosing a compact hydrophobic core. Interestingly, the head-to-tail peptide link between Trp-70 and Met-1 lies in the middle of alpha-helix 5, which is shown to have a pronounced effect on the stability of the three-dimensional structure. Analysis of structure-function relationship allowed us to propose models to understand the aspects of the molecular function of AS-48. The purpose of this work is to review recent developments in our understanding about the biochemical and biological characteristics and structure of this unusual type of bacteriocin. 相似文献
70.
We have developed an aberro-polariscope that simultaneously measures spatially resolved polarization properties and wave-front aberration in a living human eye. The setup consists of an infrared Hartmann-Shack sensor that incorporates a polariscope. A series of four Hartmann-Shack images corresponding to independent polarization states were recorded. The corresponding wave-front aberration was computed from each image. Moreover, from each set of four images spatially resolved (over the pupil plane) parameters of polarization were also determined. This instrument allows useful information on both the optical and the biomechanical properties of the eye to be obtained. 相似文献