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1.
Braz. j. oral sci ; 20: e211076, jan.-dez. 2021. tab
Artigo em Inglês | LILACS, BBO - Odontologia | ID: biblio-1253739

RESUMO

Aim: to evaluate the intra and inter-device reliability of two intraoral spectrophotometers in measuring the Commission Internationale de l'Éclairage (CIE) L*a*b* color coordinates and to compare the color difference (ΔE) between both devices. Methods: the central region of the labial surface of the maxillary central incisor of 31 participants was measured twice by each of the devices (VITA EasyShade and Degudent Shadepilot) by one examiner. CIE L*a*b* color coordinates were obtained for all teeth and ΔE was measured and compared. Intraclass correlation coefficient (ICC) and Mann-whitney U test were used to analyze the data (p<0.05). Results: inter-device reliability ICCs in measuring CIE L*a*b* color coordinates ranged between 0.08-0.49 with significant difference between devices only concerning the b coordinate (p<0.05). While intra device reliability ICCs ranged between 0.86-0.89 for VITA EasyShade and 0.81-0.86 for Degudent Shadepilot. The mean ΔE for CIE L*a*b* color coordinates of VITA EasyShade was 3.61 (±1.93) compared to 3.60 (± 1.45) for Degudent Shadepilot with insignificant difference between both devices (p>0.05). Conclusions: high intra device reliability in measuring CIE L*a*b* color coordinates was achieved particularly of Vita EasyShade, and both devices had clinically acceptable color difference (ΔE <3.7) however, inter device reliability was low to moderate. Consequently, the same spectrophotometer should be used throughout the steps of performing any tooth- colored restoration


Assuntos
Humanos , Masculino , Adulto , Espectrofotometria , Cor , Confiabilidade dos Dados
2.
Environ Monit Assess ; 193(10): 681, 2021 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-34591205

RESUMO

A simple, accurate, sensitive, and selective spectrophotometric method has been developed for the determination of mesotrione. This method is based on the reaction of mesotrione with Fe(III) to form a charge transfer metal complex having λmax at 348 nm. Beer's law was obeyed in the concentration range of 0.2-10.0 µg mL-1 with limit of detection (LOD) and limit of quantification (LOQ) equal to 0.053 and 0.162 µg mL-1, respectively. The percent recovery of mesotrione from different environmental and agricultural samples was found to be 95.00-106.50% at various levels. Notably, the developed method was successfully employed for the determination of mesotrione in environmental (pond water, canal water, tap water, and soil) and agricultural (maize grains) samples.


Assuntos
Monitoramento Ambiental , Compostos Férricos , Cicloexanonas , Espectrofotometria
3.
J Phys Chem Lett ; 12(37): 8972-8979, 2021 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-34506148

RESUMO

We present two-dimensional white-light spectroscopy (2DWL) measurements of binary and ternary bulk heterojunctions of the polymer donor PM6 mixed with state-of-the-art nonfullerene acceptors Y6 or IT4F. The ternary film has a shorter lifetime and faster spectral diffusion than either of the binary films. 2D line shape analysis of the PM6 ground state bleach with a Kubo model determines that all three films have similar amplitudes of fluctuations (Δ = 0.29 fs-1) in their transition frequencies, but different relaxation times (ranging from 102 to 24 fs). The ternary film exhibits faster dynamics than either of the binary films. The short lifetime of the ternary blend is consistent with increased photoexcitation transfer and the fast frequency fluctuations are consistent with structural dynamics of aliphatic side chains. These results suggest that the femtosecond fluctuations of PM6 are impacted by the choice of the acceptor molecules. We hypothesize that those dynamics are either indicative, or perhaps the initial source, of structural dynamics that ultimately contribute to solar cell operation.


Assuntos
Polímeros/química , Energia Solar , Microscopia de Força Atômica , Espectrofotometria
4.
Phys Chem Chem Phys ; 23(34): 18525-18534, 2021 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-34581329

RESUMO

The ultrafast dynamics triggered by the photodetachment of the tyrosinate dianion in aqueous environment shed light on the elementary processes that accompany the interaction of ionizing radiation with biological matter. Photodetachment of the tryosinate dianion yields the tyrosyl radical anion, an important intermediate in biological redox reactions, although the study of its ultrafast dynamics is limited. Here, we utilize femtosecond optical pump-probe spectroscopy to investigate the ultrafast structural reorganization dynamics that follow the photodetachment of the tyrosinate dianion in aqueous solution. Photodetachment of the tyrosinate dianion leads to vibrational wave packet motion along seven vibrational modes that are coupled to the photodetachment process. The vibrational modes are assigned with the aid of density functional theory (DFT) calculations. Our results offer a glimpse of the elementary dynamics of ionized biomolecules and suggest the possibility of extending this approach to investigate the ionization-induced structural rearrangement of other aromatic amino acids and larger biomolecules.


Assuntos
Radicais Livres/química , Tirosina/química , Ânions/química , Teoria da Densidade Funcional , Hidróxido de Sódio/química , Espectrofotometria , Água/química
5.
J Photochem Photobiol B ; 222: 112271, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34364080

RESUMO

Photobiomodulation (PBM) describes the use of low irradiance light in the red to near-infrared wavelength range to stimulate biological effects in tissue, and many biological and spectroscopic techniques are used to study PBM. However, these techniques focus on the products or downstream effects rather than the electronic transitions that initiate the PBM processes. This study presents a novel approach to studying low irradiance light exposures on individual proteins and/or protein complexes by combining a continuous wave (CW) laser diode with femtosecond transient absorption spectroscopy (TAS), coined here as CW-TAS, and tests the system on reduced cytochrome c (Cyt c) for proof of principle. TAS was conducted using a 532-nm excitation pump beam and a 350-600 nm supercontinuum probe. CW laser diodes with wavelengths of 450 nm, 635 nm, and 808 nm were interchangeably fiber coupled into the HELIOS Fire. Samples of Cyt c were tested by TAS using a pump power of 15 µW, both with and without CW exposure. CW exposures were carried out with irradiances of 1.60 and 3.20 mW/cm2, except for 808 nm, which was only tested at 1.60 mW/cm2. Both kinetic and global analyses were performed on the TAS data and the time constants for sets with and without CW exposures were compared. The TAS data for Cyt c with the full dosage of CW exposures did not alter the TAS data distinguishably from the control data. No new electronic transient signals were observed beyond the background when testing Cyt c with the CW exposures. Kinetic analysis confirmed that existing transients did not deviate beyond uncertainty. Global time constants for Cyt c were calculated to be 0.25 ± 0.03 ps and 5.1 ± 0.3 ps for the control study, and the time constants for the CW exposed Cyt c were not significantly different. This study concludes that CW irradiation, at doses delivered, does not alter the transient absorption data of Cyt c. The CW-TAS method provides a new tool for studying PBM effects in other proteins and protein complexes that might respond to the CW wavelengths, such as Complex IV, in future studies.


Assuntos
Lasers Semicondutores , Espectrofotometria/métodos , Citocromos c/química , Cinética , Luz , Oxirredução
6.
Anal Methods ; 13(34): 3779-3784, 2021 09 02.
Artigo em Inglês | MEDLINE | ID: mdl-34350441

RESUMO

This research paper presents simple and quick eco-friendly spot test and spectrophotometric methods for the determination of L-glutathione. The spot test assay is based on the formation of a color complex with phenazine methosulphate and L-glutathione on a thin-layer chromatography plate followed by image analysis using a scanner as a detector. For analysis, the image was converted into red, green, and blue (RGB) histograms. A series of parameters that influenced the color formation were investigated, and under the optimal conditions, a good linearity was observed in the range of 200-1000 µg mL-1 and 249-1000 µg mL-1 of L-glutathione with correlation coefficients of 0.9907 for B and 0.9903 for G channels. For the spectrophotometric method, a good linearity was obtained in the range of 2.1-60 µg mL-1 of L-glutathione concentration with a correlation coefficient of 0.9961. A mechanism of the reaction of L-glutathione with phenazine was proposed and confirmed by Fourier transform infrared and mass spectroscopy.


Assuntos
Glutationa , Fenazinas , Cromatografia em Camada Delgada , Metilfenazônio Metossulfato , Espectrofotometria
7.
Anal Methods ; 13(32): 3627-3631, 2021 08 28.
Artigo em Inglês | MEDLINE | ID: mdl-34378548

RESUMO

The analytical determination of lithium ions is usually performed by atomic absorption and X-ray fluorescence methods. Chemical analysis based on polyfluoroporphyrin chromogenic methods is also being employed, especially for biological samples. However, all existing methods are expensive and not suitable for routine work or field assays. The alternative method proposed here is based on the formation of a LiKFe(IO6) compound which is converted into a tris(1,10-phenanthroline)iron(ii) complex and monitored by spectrophotometric or colorimetric methods, the latter using a smartphone app. Under similar conditions, these two methods proved superior to the X-ray fluorescence method. A one pot analysis of lithium ions is also described, using an Eppendorf microtube previously modified for performing reaction, filtration and detection. This method is simple and very convenient for didactic and field assays.


Assuntos
Colorimetria , Lítio , Íons , Ferro , Espectrofotometria
8.
Rev. Odontol. Araçatuba (Impr.) ; 42(2): 18-23, maio-ago. 2021. tab
Artigo em Português | LILACS, BBO - Odontologia | ID: biblio-1252902

RESUMO

O objetivo do estudo foi realizar uma revisão narrativa da literatura para comparar os métodos visual e instrumental de seleção da cor dentária, correlacionando-os com o fator experiência e a educação continuada. Utilizou-se como base de dados a MEDLINE na qual foram aplicados os descritores "visualshade match", "color measurement", "spectrophotometer" e "tooth color determination". Os critérios de inclusão foram artigos publicados entre 2010 e 2020que abordassem uma análise comparativa entre as duas modalidades de seleção da cor dentária. Se enquadraram nos critérios de exclusão estudos que não contemplavam a temática abordada e aqueles publicados nos anos anteriores a 2010, além das revisões de literatura. No total, onze artigos foram selecionados para compor essa revisão. Os estudos demonstraram que o método instrumental apresentou maior confiabilidade e reprodutibilidade quando comparado ao método visual, isso se deve ao fato de a escolha de cor através de instrumentos eletrônicos proporcionar melhor precisão e atenuação da subjetividade. No que concerne a experiência como fator influenciador da seleção de cor, os estudos são controversos. Mesmo evidenciando melhor precisão, a estimativa instrumental apresenta limitações devido à dificuldade de aferição em função da convexidade da anatomia dentária. Desse modo, foi descrito que a associação de métodos é capaz de elevar a confiabilidade da escolha de cor, melhorando o resultado estético. Não houve consenso entre os estudos com relação à influência da experiência, no entanto, a educação continuada foi sugerida na literatura como alternativa para formar profissionais mais confiantes no processo de seleção de tonalidades(AU)


The goal of this study was to carry out a narrative review of the literature to compare the visual and instrumental methods of tooth color selection, correlating them with the experience factor and continuing education. MEDLINE was used as a database in which the descriptions such as "visual shade match", "color measurement", "spectrophotometer" and "tooth color determination" were applied. The inclusion criteria were articles published between 2010 and 2020 that addressed a comparative analysis between the two types of tooth color selection. The exclusion criteria included studies that did not contemplate the theme addressed and those published in the years prior to 2010, in addition to literature reviews. In total, eleven articles were selected to compose this review. Studies have shown that the instrumental method showed greater reliability and reproducibility when compared to the visual method, this is due to the fact that the color's choice through electronic instruments provides better precision and lessened subjectivity. Regarding experience as na influencing factor in color selection, studies are controversial. Even with better precision, the instrumental estimation has limitations due to the difficulty of measuring it due to the convexity of the dental anatomy. Thus, it was described that the association of the methods is able to increase the reliability of the color's choice, improving the aesthetic result. There was no consensus among the studies in regard to the experiment's influence, however, continuing education was suggested in the literature as an alternative in order to form more confident professionals when it comes to the shade selection process(AU)


Assuntos
Cor , Estética Dentária , Espectrofotometria
9.
Phys Chem Chem Phys ; 23(37): 20867-20874, 2021 Sep 29.
Artigo em Inglês | MEDLINE | ID: mdl-34374395

RESUMO

Cyanobacteriochromes (CBCRs) are bi-stable photoreceptor proteins with high potential for biotechnological applications. Most of these proteins utilize phycocyanobilin (PCB) as a light-sensing co-factor, which is unique to cyanobacteria, but some variants also incorporate biliverdin (BV). The latter are of particular interest for biotechnology due to the natural abundance and red-shifted absorption of BV. Here, AmI-g2 was investigated, a CBCR capable of binding both PCB and BV. The assembly kinetics and primary photochemistry of AmI-g2 with both chromophores were studied in vitro. The assembly reaction with PCB is roughly 10× faster than BV, and the formation of a non-covalent intermediate was identified as the rate-limiting step in the case of BV. This step is fast for PCB, where the formation of the covalent thioether bond between AmI-g2 and PCB becomes rate-limiting. The photochemical quantum yields of the forward and backward reactions of AmI-g2 were estimated and discussed in the context of homologous CBCRs.


Assuntos
Biliverdina/química , Cianobactérias/metabolismo , Fotorreceptores Microbianos/química , Ficobilinas/química , Ficocianina/química , Biliverdina/metabolismo , Cinética , Fotorreceptores Microbianos/genética , Fotorreceptores Microbianos/metabolismo , Ficobilinas/metabolismo , Ficocianina/metabolismo , Ligação Proteica , Teoria Quântica , Espectrofotometria
10.
J Photochem Photobiol B ; 223: 112278, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34416475

RESUMO

The pure spectra acquisition of plant disease symptoms is essential to improving the reliability of remote sensing methods in crop protection. The reflectance values read from the pure spectra can be used as valuable training data for development of algorithms designed for plant disease detection at leaf and canopy scale. The aim of this paper is to identify and distinguish spectrally the leaf rust symptoms caused by two closely related special forms (f. sp.) of Puccinia recondita f. sp. tritici on wheat and Puccinia recondita f. sp. recondita on rye at leaf scale. Spectral measurements were made with FieldSpec 3 spectrometer in the wavelength range of 350-2500 nm. The spectrometer was connected to a microscope by optical fiber. Raw spectra of uredinia, chlorotic discoloration, green leaves, senescent inoculated leaves and senescent uninoculated leaves of wheat and rye, all of which obtained for this study, were investigated with a view towards making an automized classification of plant species and their phases. The created Random Forest models were tested separately using pure spectra, and from these vegetation indices were derived as predictors. Three vegetation indices, namely CRI, PRI and GNDVI, appeared to be the most robust in terms of distinguishing uredinia from other symptoms on rye and wheat leaves. PRI, EVI, NDVI705, and GNDVI were the most suitable for distinguishing uredinia, chlorotic discoloration, and green leaf stages on rye. That tusk on wheat leaves can be recognized if seven indices (PRI, MSAWI, SAVI, NDVI, NDVI705, GNDVI and RVI) are used together. For the classification of all disease symptoms for both plant species, the most useful were wavelengths in the VIS range: 431-436, 696-703 and 646-686 nm. However, the ranges of SWIR wavelengths (1938, 1955) and NIR wavelengths (1099-1104) also have a high contribution to the discrimination accuracy of the model. In the classification of all disease symptoms, the most important vegetation indices were CRI, OSAVI, and GNDVI. Analysis of the results revealed the advantage of the model based on the selected spectral wavelengths (Hit Rate of 96.6%) in comparison with predictions based on vegetation indices alone (Hit Rate of 91.7%). Both approaches show the highly applicable character of utilizing high quality spectral products such as satellite images in reducing operational costs of crop protection.


Assuntos
Algoritmos , Lolium/química , Doenças das Plantas/classificação , Triticum/química , Análise Discriminante , Lolium/crescimento & desenvolvimento , Lolium/metabolismo , Microscopia , Doenças das Plantas/microbiologia , Folhas de Planta/química , Folhas de Planta/metabolismo , Puccinia/fisiologia , Secale , Espectrofotometria , Triticum/crescimento & desenvolvimento , Triticum/metabolismo
11.
Methods Mol Biol ; 2350: 1-20, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34331275

RESUMO

Signal transduction processes are a necessary component of multicellular life, and their dysregulation is the basis for a host of syndromes and diseases. Thus, it is imperative that we discover the complex details of how signal transduction processes result in specific cellular outcomes. One of the primary mechanisms of regulation over signaling pathways is through spatiotemporal control. However, traditional methods are limited in their ability to reveal such details. To overcome these limitations, researchers have developed a variety of genetically encodable, fluorescent protein-based biosensors to study these dynamic processes in real time in living cells. Due to the complexities and interconnectedness of signaling pathways, it is thus desirable to use multiple biosensors in individual cells to better elucidate the relationships between signaling pathways. However, multiplexed imaging with such biosensors has been historically difficult. Nevertheless, recent developments in designs and multiplexing strategies have led to vast improvements in our capabilities. In this review, we provide perspectives on the recently developed biosensor designs and multiplexing strategies that are available for multiplexed imaging of signal transduction pathways.


Assuntos
Técnicas Biossensoriais/métodos , Imagem Molecular/métodos , Transdução de Sinais , Biomarcadores , Transferência Ressonante de Energia de Fluorescência/métodos , Espaço Intracelular/metabolismo , Proteínas Luminescentes/genética , Proteínas Luminescentes/metabolismo , Microscopia de Fluorescência , Transporte Proteico , Espectrofotometria
12.
Forensic Sci Int ; 325: 110891, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34247141

RESUMO

This study examines the spectral characteristics of blood after being exposed to intense heat within a structural fire. Fire and intense heat have previously been understood to destroy or chemically change bloodstain evidence so that traditional forensic science recovery techniques are rendered ineffectual. Understanding the effects of the denaturation process and physical changes that occur to blood when exposed to heat may develop innovative forensic investigation methods, including the use of reflected infrared photography to enhance the recording of bloodstains. This research revealed that the denaturation of blood, specifically changes to the haemoglobin state from oxyhaemoglobin to methaemoglobin, resulted in the heat affected blood having a more optimal spectral target range within the infrared region when exposed to heat> 200 °C. It was observed both qualitatively and quantitatively using spectrophotometry, that there is a relationship between the appearance, viscosity and infrared absorption properties of blood when exposed to different temperatures as experienced in fire. This result indicated the increased potential for reflected infrared photography to be utilised as an effective tool for crime scene evidence recovery of bloodstains from arson scenes involving fire.


Assuntos
Análise Química do Sangue , Manchas de Sangue , Incêndios , Viscosidade Sanguínea , Cor , Piromania , Humanos , Metemoglobina/análise , Oxiemoglobinas/análise , Espectrofotometria
13.
Spectrochim Acta A Mol Biomol Spectrosc ; 263: 120137, 2021 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-34273891

RESUMO

Five simple, selective and accurate spectrophotometric methods have been applied and developed for first time for simultaneous determination of amlodipine besylate (AML) and celecoxib (CEL) in presence of one harmful impurity, 4-methylacetophenone (MAP), in their ternary mixture without prior separation. Those spectrophotometric methods were developed and called: dual wave length in ratio spectra (DWRS), successive ratio-derivative spectra (SDR), modified absorption factor method (MAFM), modified amplitude center method (MACM) and first derivative -zero crossing coupled with amplitude factor method (FDAF). These methods include various steps using zero /or ratio /or derivative spectra and some mathematical techniques. Linear calibration curves were constructed over the concentration range of 2-100, 10-200 and 0.5-20 µg/mL for AML, CEL and MAP, respectively. High sensitivity with low LOD values 0.583, 3.118 and 0.147 for AML, CEL and MAP, respectively were obtained. Moreover, validation of the proposed methods was achieved according to ICH guidelines and satisfactory results were obtained indicating that the developed methods can be used for quality control analysis of AML and CEL concerning its impurity. No significant difference was observed when the obtained results of the developed methods were statistically compared with the reported HPLC method.


Assuntos
Anlodipino , Celecoxib , Espectrofotometria
14.
Spectrochim Acta A Mol Biomol Spectrosc ; 263: 120192, 2021 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-34314967

RESUMO

In this research, the simultaneous absorption of Salmeterol (SAL) and Fluticasone (FLU) in Seroflo spray was investigated using a spectrophotometric device via employing continuous wavelet transform (CWT) and radial basis function neural network (RBF-NN) methods. Root mean square error (RMSE) related to the RBF model was obtained 3.17 × 10-13 and 1.41 × 10-13 for SAL and FLU, respectively. Limit of detection (LOD) and limit of quantification (LOQ) corresponding to the CWT method were 0.004, 0.280 µg/mL, and 0.431, 0.479 µg/mL for SAL and FLU, respectively. Root mean square error (RMSE) of SAL and FLU was obtained 3.17 × 10-13 and 1.41 × 10-13, respectively in RBF-NN method. In the end, the results obtained from all methods were compared with the high-performance liquid chromatography (HPLC) as a reference method. According to the one-way analysis of variance with a 95% confidence level, there is no significant difference between the proposed techniques and HPLC. Therefore, chemometrics methods are sufficiently accurate, as the reference method for the analysis of drugs. The suggested methods are simple, fast, and cheap. Also, there is no need for pre-preparation steps. These methods can be used for quality control laboratories in the pharmaceutical industry.


Assuntos
Redes Neurais de Computação , Análise de Ondaletas , Fluticasona , Xinafoato de Salmeterol , Espectrofotometria
15.
Spectrochim Acta A Mol Biomol Spectrosc ; 263: 120190, 2021 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-34332240

RESUMO

This study proposed simple and reliable spectrophotometry method for simultaneous analysis of hepatitis C antiviral binary mixture containing sofosbuvir (SOF) and daclatasvir (DAC). This technique is based on the use of feed-forward artificial neural network (FF-ANN) and least square support vector machine (LS-SVM). FF-NN with Levenberg-Marquardt (LM) and Cartesian genetic programming (CGP) algorithms was trained to determine the best number of hidden layers and the number of neurons. This comparison demonstrated that the LM algorithm had the minimum mean square error (MSE) for SOF (1.59 × 10-28) and DAC (4.71 × 10-28). In LS-SVM model, the optimum regularization parameter (γ) and width of the function (σ) were achieved with root mean square error (RMSE) of 0.9355 and 0.2641 for SOF and DAC, respectively. The coefficient of determination (R2) value of mixtures containing SOF and DAC was 0.996 and 0.997, respectively. The percentage recovery values were in the range of 94.03-104.58 and 94.04-106.41 for SOF and DAC, respectively. Statistical test (ANOVA) was implemented to compare high-performance liquid chromatography (HPLC) and spectrophotometry, which showed no significant difference. These results indicate that the proposed method possesses great potential ability for prediction of concentration of components in pharmaceutical formulations.


Assuntos
Hepatite C , Preparações Farmacêuticas , Algoritmos , Composição de Medicamentos , Hepacivirus , Humanos , Análise dos Mínimos Quadrados , Redes Neurais de Computação , Reprodutibilidade dos Testes , Espectrofotometria , Máquina de Vetores de Suporte
16.
Methods Mol Biol ; 2350: 173-190, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34331286

RESUMO

Deciphering protein-protein interactions (PPIs) in vivo is crucial to understand protein function. Bimolecular fluorescence complementation (BiFC) makes applicable the analysis of PPIs in many different native contexts, including human live cells. It relies on the property of monomeric fluorescent proteins to be reconstituted from two separate subfragments upon spatial proximity. Candidate partners fused to such complementary subfragments can form a fluorescent protein complex upon interaction, allowing visualization of weak and transient PPIs. It can also be applied for investigation of distinct PPIs at the same time using a multicolor setup. In this chapter, we provide a detailed protocol for analyzing PPIs by doing BiFC in cultured cells. Proof-of-principle experiments rely on the complementation property between the N-terminal fragment of mVenus (designated VN173) and the C-terminal fragment of mCerulean (designated CC155) and the partnership between HOXA7 and PBX1 proteins. This protocol is compatible with any other fluorescent complementation pair fragments and any type of candidate interacting proteins.


Assuntos
Microscopia de Fluorescência por Excitação Multifotônica/métodos , Imagem Molecular/métodos , Mapeamento de Interação de Proteínas/métodos , Linhagem Celular , Rastreamento de Células , Análise de Dados , Expressão Gênica , Ordem dos Genes , Vetores Genéticos , Humanos , Proteínas Luminescentes/genética , Proteínas Luminescentes/metabolismo , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Espectrofotometria , Transfecção
17.
Methods Mol Biol ; 2341: 1-7, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34264454

RESUMO

Many S. aureus strains produce membrane-associated carotenoid pigments, advantageous secondary metabolites that can alter membrane fluidity, resistance to antimicrobial peptides (AMPs) and act as antioxidants, properties that can impact resistance against aspects of the host innate immune system. Several studies have reported connections between mutations in both regulatory (i.e., alternative sigma factor B) and metabolic (purine biosynthesis, oxidative phosphorylation) genes, and noticeable differences in carotenoid pigmentation. This chapter outlines a simple protocol to quantify cellular pigments using a methanol extraction method.


Assuntos
Carotenoides/isolamento & purificação , Metanol/química , Staphylococcus aureus/crescimento & desenvolvimento , Carotenoides/química , Fracionamento Químico , Regulação Bacteriana da Expressão Gênica , Fluidez de Membrana , Espectrofotometria , Staphylococcus aureus/metabolismo
18.
Methods Mol Biol ; 2341: 69-78, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34264462

RESUMO

Most Staphylococcus aureus strains can grow as a multicellular biofilm, a phenotype of utmost importance to clinical infections such as endocarditis, osteomyelitis, and implanted medical device infection. As biofilms are inherently more tolerant to the host immune system and antibiotics, understanding the S. aureus genes and regulatory circuits that contribute to biofilm development is an active and on-going field of research. This chapter details a high-throughput and standardized way to grow S. aureus biofilms using a classical microtiter plate assay. Biofilms can be quantified using crystal violet or by confocal microscopy imaging and COMSTAT analysis.


Assuntos
Biofilmes/crescimento & desenvolvimento , Violeta Genciana/farmacologia , Staphylococcus aureus/fisiologia , Técnicas Bacteriológicas , Microscopia Confocal , Espectrofotometria
19.
Molecules ; 26(13)2021 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-34206735

RESUMO

The impact of key classes of compounds found in wine on protein removal by the ion-exchange resin, Macro-Prep® High S, was examined by adsorption isotherm experiments. A model wine system, which contained a prototypical protein Bovine Serum Albumin (BSA), was used. We systematically changed concentrations of individual chemical components to generate and compare adsorption isotherm plots and to quantify adsorption affinity or capacity parameters of Macro-Prep® High S ion-exchange resin. The pH (hydronium ion concentration), ethanol concentration, and prototypical phenolics and polysaccharide compounds are known to impact interactions with proteins and thus could alter the adsorption affinity and capacity of Macro-Prep® High S ion-exchange resin. At low equilibrium protein concentrations (< ~0.3 (g BSA)/L) and at high equilibrium protein concentrations in model wines at various pH, the adsorption behavior followed the Langmuir isotherm, most likely due to the resin acting as a monolayer adsorbent. The resulting range of BSA capacity was between 0.15-0.18 (g BSA)/(g Macro-Prep® High S resin). With the addition of ethanol, catechin, caffeic acid, and polysaccharides, the protein adsorption behavior was observed to differ at higher equilibrium protein concentrations (> ~0.3 (g BSA)/L), likely as a result of Macro-Prep® acting as an unrestricted multilayer adsorbent at these conditions. These data can be used to inform the design and scale-up of ion-exchange columns for removing proteins from wines.


Assuntos
Etanol/química , Resinas de Troca Iônica/química , Proteínas/química , Soroalbumina Bovina/química , Vinho/análise , Adsorção , Ácidos Cafeicos/química , Catequina/química , Concentração de Íons de Hidrogênio , Cinética , Modelos Químicos , Fenóis/análise , Polissacarídeos/química , Soluções/análise , Soluções/química , Espectrofotometria , Água/química
20.
Spectrochim Acta A Mol Biomol Spectrosc ; 262: 120106, 2021 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-34214740

RESUMO

A simple, cheap, and environmentally friendly centrifuge-less cloud point extraction procedure was developed for the preconcentration of traces of Cu(II) before its spectrophotometric determination. It is based on a complexation reaction with the hydrophobic azo reagent 6-hexyl-4-(2-thiazolylazo)resorcinol (HTAR), in which a complex with a stoichiometric ratio of 1:1 and an absorption maximum at 535 nm is formed. The experimental conditions for Cu(II) determination were found: HTAR concentration (8 × 10-6 mol mL-1), mass fraction of the surfactant Triton X-114 (2.2%), pH (5.9, ammonium acetate buffer), and incubation time (10 min at 60 °C). The linear range, limit of detection, molar absorption coefficient and preconcentration factor were calculated to be 4.5-254 ng mL-1, 1.34 ng mL-1, 2.54 × 105 L mol-1 cm-1, and 10, respectively. The effect of foreign ions was studied, and the proposed procedure was applied to the analysis of water samples and a saline solution for intravenous infusion.


Assuntos
Cobre , Polietilenoglicóis , Compostos Azo , Resorcinóis , Espectrofotometria
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