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1.
J Phys Chem Lett ; 11(3): 1030-1037, 2020 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-31967828

RESUMO

Very recently, the bulk synthesis of cyclo-N5- from arylpentazole through the treatment with m-chloroperbenzonic acid (m-CPBA) and ferrous bisglycinate ([Fe(Gly)2]) (Zhang, C., et al. Science 2017, 355, 374) has greatly promoted the application of pentazolate anion as a novel high-performance energetic material. Yet the mechanism for this reaction is still unexplored. Herein we perform mechanistic studies on the selective C-N bond cleavage in arylpentazole by using density functional theory methods. The direct C-N bond activation by m-CPBA was computed to be kinetically inaccessible. Instead, the oxidation of [Fe(Gly)2] by m-CPBA is much favorable, which leads to the generation of a high-valent iron(IV)-oxo product. The Fe(IV)-oxo intermediate has been examined by UV-vis absorption spectra experiments and further verified by excited-state calculations. It is found that the Fe(IV)-oxo serves as the key intermediate for the C-N bond activation of arylpentazole and the cyclo-N5- generation. Our calculations clarified the key mechanistic details of the cyclo-N5- generation, and the factors that affect the production yield are further discussed.


Assuntos
Clorobenzoatos/química , Compostos Ferrosos/química , Glicina/química , Modelos Moleculares , Pentilenotetrazol/química , Carbono/química , Nitrogênio/química , Oxirredução , Teoria Quântica , Espectrofotometria , Termodinâmica
2.
J Photochem Photobiol B ; 203: 111768, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31931383

RESUMO

In vitro callus cultures of Verbena officinalis L. were maintained on solid Murashige and Skoog medium, enriched with 1 mg dm-3 BA and 1 mg dm-3 IBA under LED lights (red, blue, red/blue 70%/30%), in darkness and under control fluorescent lamps. The measurements of 2 phenylpropanoid glycosides (verbascoside and isoverbascoside) and 23 phenolic acids were performed in methanolic extracts from the biomass collected after 2-, 3- and 4-week growth cycles using the HPLC-DAD method. The presence of verbascoside, isoverbascoside and additionaly 7 phenolic acids (protocatechuic, chlorogenic, vanillic, caffeic, ferulic, o-coumaric and m-coumaric acids) was confirmed in all extracts. Blue and red/blue lights stimulated the accumulation of verbascoside (max. of 6716 and 6023 mg 100 g-1 DW after a 4-week growth cycle) and isoverbascoside (max. 333 and 379 mg 100 g-1 DW also after 4 weeks). The maximum amounts of verbascoside and isoverbascoside were respectively 1.8- and 7.0-fold higher than under the control conditions. Phenolic acids were accumulated in different amounts, and the maximum total amounts ranged from 36 to 65 mg 100 g-1 DW. LED lights also stimulated their accumulation in comparison with darkness and control. The main phenolic acids included: m-coumaric acid (max. 39 mg 100 g-1 DW), ferulic acid (max. 12 mg 100 g-1 DW), and protocatechuic acid (max. 13 mg 100 g-1 DW). Additionally, the quantities of photosynthetic pigments (chlorophyll a, b and carotenoids) were estimated in acetonic extracts using spectrophotometry. Red/blue light stimulated the biosynthesis of pigments (max. total content 287 µg g-1 FW after 4-week growth cycles). This is the first study describing the effect of LED lights on the production of phenylpropanoid glycosides and phenolic acids in V. officinalis callus cultures. Very high amounts of verbascoside and isoverbascoside are interesting from a practical point of view.


Assuntos
Glucosídeos/metabolismo , Hidroxibenzoatos/metabolismo , Luz , Fenóis/metabolismo , Verbena/metabolismo , Biomassa , Carotenoides/análise , Clorofila/análise , Clorofila A/análise , Cromatografia Líquida de Alta Pressão , Glucosídeos/análise , Hidroxibenzoatos/análise , Fenóis/análise , Fotossíntese/efeitos da radiação , Análise de Componente Principal , Análise de Regressão , Espectrofotometria
3.
Forensic Sci Int ; 306: 110063, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31790891

RESUMO

Diagnosis of carbon monoxide (CO) poisonings has always been a challenging task due to the susceptibility to alterations of the optical state and degradation of blood samples during sampling, transport and storage, which highly affects the analysis with spectrophotometric methods. Methodological improvements are then required urgently because of increased reports of cases with discrepancies between results of the measured biomarker carboxyhemoglobin (COHb) and reported symptoms. Total blood CO (TBCO) measured chromatographically was thus proposed in a previous study as alternative biomarker to COHb. This approach was investigated in this study by comparing the two biomarkers and assessing the effects of various storage parameters (temperature, preservative, time, tube headspace (HS) volume, initial saturation level, freeze- and thaw- and reopening-cycles) over a period of one month. Results show that while for TBCO, concentrations are relatively stable over the observation period regardless of parameters such as temperature, time and HS volume, for COHb, concentrations are altered significantly during storage. Therefore, the use of TBCO as alternative biomarker for CO poisonings has been proposed, since it provides more valid results and is more stable even under non-optimal storage conditions. Additionally, it can be used to predict COHb in cases where sample degradation hinders optical measurement. Furthermore, a correction formula for COHb and TBCO is provided to be used in laboratories or circumstances where optimal storage or analysis is not possible, to obtain more accurate results.


Assuntos
Intoxicação por Monóxido de Carbono/diagnóstico , Monóxido de Carbono/sangue , Carboxihemoglobina/análise , Medicina Legal/métodos , Biomarcadores/sangue , Cromatografia Gasosa , Interpretação Estatística de Dados , Humanos , Oximetria , Manejo de Espécimes , Espectrofotometria
4.
Acta Odontol Scand ; 78(1): 31-37, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31349769

RESUMO

Objectives: To determine the baseline perfusion parameters of the alveolar mucosa using laser Doppler flowmetry and tissue spectrophotometry (LDF-TS) in healthy adults.Material and methods: Forty-two healthy adult subjects of either sex were tested. The perfusion of the alveolar mucosa was evaluated using a laser Doppler flowmetry and tissue spectrophotometry using O2C 'oxygen to see' device. The measurements encompassed the maxillary and mandibular mucosa at 20 different points.Results: The O2C device is a reliable method for noninvasive measurement of different perfusion parameters of the oral mucosa. The hemoglobin saturation values (So2 in %), as well as relative amount of hemoglobin in arbitrary units (AU) of the maxillary mucosa demonstrated lower values of that in the mandible. The flow value (AU) exhibited a significant difference in the posterior molar region only, while the velocity value (AU) showed a significant difference across all points except for the anterior region.Conclusion: the present study provides a set of brand-new perfusion parameters of the microcirculation of the alveolar mucosa using LDF-TS. The study suggests a variation of the perfusion parameters between the maxilla and the mandible. Differences in the anatomy of the blood supply, the thickness of the mucosa and the cortical bone, may be attributed to this variation. Further studies using different probes and a combination of ultrasonic measurements and SDF imaging will aid in giving a better overview of the perfusion in the oral mucosa.


Assuntos
Fluxometria por Laser-Doppler/métodos , Mandíbula/irrigação sanguínea , Maxila/irrigação sanguínea , Microcirculação/fisiologia , Mucosa Bucal/irrigação sanguínea , Oxigênio/fisiologia , Espectrofotometria/métodos , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Perfusão
5.
Food Chem ; 305: 125506, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31606690

RESUMO

Grapes are known to contain high quantity of polyphenolic compounds, including caffeic, coumaric and ferulic acids esterified with tartaric acid, to yield caftaric, coutaric and fertaric acids, respectively. These acids are more abundant in unripe grapes, which can be processed into verjuice, a product that shows intrinsic resistance against microbial growth and significant antioxidant activity. In the present work, the isolation of hydroxycinnamoyl tartaric acids from unripe grape juice by chromatographic techniques was described. Moreover, the capability of caftaric acid to inhibit tyrosinase activity was evaluated by spectrophotometric assays. According to the kinetics parameters calculated, caftaric acid was shown to be a competitive inhibitor of tyrosinase, more potent than the related caffeic and chlorogenic acids, suggesting that it can be used in cosmetic and food industries for the development of natural skin whitening formulations and as an agent able to counteract the enzymatic browning of food.


Assuntos
Sucos de Frutas e Vegetais/análise , Monofenol Mono-Oxigenase/antagonistas & inibidores , Extratos Vegetais/isolamento & purificação , Extratos Vegetais/farmacologia , Espectrofotometria , Vitis/química , Inibidores Enzimáticos/isolamento & purificação , Inibidores Enzimáticos/farmacologia
6.
Artigo em Inglês | MEDLINE | ID: mdl-31815970

RESUMO

The present paper presents clinical guidelines for the selection of the abutment material and level of customization for single-implant reconstructions. A systematic literature search was conducted previous to a Consensus Conference, resulting in two systematic reviews. One review focused on esthetic clinical outcomes, including esthetic indices and linear measurements, and the second focused on peri-implant soft tissue color outcomes, evaluated with spectrophotometry. The outcomes of esthetic indexes and linear measurement were highly heterogenic, hence, a meta-analysis was not feasible. All-ceramic and customized solutions showed a trend for improved results of the esthetic outcomes. Regarding soft tissue color outcomes, all-ceramic abutments induced significantly less soft tissue color changes. Both metallic and all-ceramic abutments/standard and customized components may result in clinically and esthetically acceptable reconstructions.


Assuntos
Dente Suporte , Implantes Dentários para Um Único Dente , Cerâmica , Coroas , Estética Dentária , Espectrofotometria , Titânio , Zircônio
7.
Food Chem ; 304: 125383, 2020 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-31479997

RESUMO

An aqueous two-phase system was used in conjunction with ultrasonic cell disruption to extract and separate solanine (mainly solasonine and solamargine) and Solanum nigrum polysaccharide from Solanum nigrum unripe fruit. The optimized conditions of the present study were determined by a single-factor experiment and a multifactor experiment. The concentration of ethanol was set at 60% and the duration of the ultrasonic cell disruption extraction was 50 min. In the ethanol-K2CO3 aqueous two-phase separation system, the concentration of ethanol was 36%, the concentration of K2CO3 was 0.21 mg·mL-1, and the temperature was 15 °C. The solasonine and solamargine were determined by high-performance liquid chromatography, and the Solanum nigrum polysaccharide was determined by an ultraviolet-visible spectrophotometer in accordance with the phenol-sulfuric acid method. xUnder optimized conditions, the average extraction efficiencies of solasonine, solamargine and Solanum nigrum polysaccharide were 95.86%, 95.95% and 96.95%, respectively, and the average separation efficiencies of solasonine, solamargine and Solanum nigrum polysaccharide were 2.07 mg·g-1, 2.05 mg·g-1 and 8.15 mg·g-1, respectively.


Assuntos
Frutas/química , Polissacarídeos/isolamento & purificação , Solanina/análise , Solanum nigrum/química , Ultrassom , Cromatografia Líquida de Alta Pressão , Polissacarídeos/análise , Alcaloides de Solanáceas/análise , Alcaloides de Solanáceas/isolamento & purificação , Espectrofotometria
8.
Talanta ; 206: 120250, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31514846

RESUMO

The development of a simple and economical spectrophotometric system based on the use of a device created by 3D printing and the electronics necessary to control the intensity of the radiation source was described. The measurements are made with a low-cost digital webcam. The entire system is only powered through the USB outputs of a computer, which makes the portable and really practical system for the measurements in the field. This method was applied to determine iron (II) in waters using o-phenanthroline as chromogenic reagent giving a red complex, and also to hypochlorite determination using tetramethylbenzidine as the reagent providing a yellow color. The calibration curves were built using a mathematical algorithm making a RGB deconvolution. The intense of colors obtained from a webcam in each concentration of analyte had a relationship with the absorbance values. In order to confirm the accuracy and precision of this method, a traditional spectrophotometer was used for validation.


Assuntos
Computadores , Fotografação/instrumentação , Impressão Tridimensional , Espectrofotometria/instrumentação , Benzidinas/química , Calibragem , Ácido Hipocloroso/análise , Ferro/análise , Limite de Detecção , Fenantrolinas/química , Espectrofotometria/métodos
9.
Int J Prosthodont ; 33(1): 39-47, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31860912

RESUMO

PURPOSE: To systematically review the current literature on the influence of abutment material (metal vs ceramic) and soft tissue thickness on peri-implant soft tissue discoloration in partially edentulous patients restored with implant-supported single crowns. METHODS: An electronic MEDLINE search was performed to identify randomized controlled clinical trials (RCTs) up to and including March 2017. The search was complemented by a manual search of related bibliographies. Selection of studies was made independently by two reviewers based on the inclusion criteria. Spectrophotometric data (ΔE values) and soft tissue thickness values were extracted, and, whenever applicable, a meta-analysis using a random-effects approach was performed. RESULTS: The search resulted in 208 titles and 30 abstracts. Full-text analysis was performed for 13 articles, resulting in 6 included RCTs. Meta-analysis of a total of 266 abutments revealed significantly lower ΔE values for ceramic abutments when compared to the overall metal abutments (z test value = 1.99, P = .05), with a mean difference of 1.41 (95% CI 0.02, 2.80). Nonsignificant differences were found between titanium and zirconia (z test value = 1.59, P = .11). Limited information on the correlation between soft tissue thickness and ΔE values was found. Hence, it was not possible to perform a meta-analysis of this question. CONCLUSION: The color outcome of the peri-implant soft tissue might be influenced by the abutment material. Ceramic abutments appear to provide an improved color matching between peri-implant soft tissues and soft tissues around natural teeth when compared to metallic abutments. These findings support the preference for all-ceramic or "white" abutments in esthetically demanding cases.


Assuntos
Dente Suporte , Implantes Dentários para Um Único Dente , Coroas , Gengiva , Humanos , Ensaios Clínicos Controlados Aleatórios como Assunto , Espectrofotometria , Titânio , Zircônio
10.
Chemosphere ; 238: 124664, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31472349

RESUMO

Chemosensors have already demonstrated potential for the detection and imaging of metal ions in solutions and biological systems, however, their applications to soil analysis are limited. This study explores the potential of utilizing a chemosensor for the detection of exchangeable Cu2+ in soils via qualitative (solution visual color change) and quantitative (UV-Vis spectrophotometry) approaches. Montmorillonite and kaolin clays were doped with Cu(NO3)2 solutions from 2.5 to 50 mM, and contaminated soil samples were collected from a historic copper mine. The exchangeable Cu2+ was extracted using a standard CaCl2 cation exchange approach, and the Cu2+ concentration in the resulting solutions determined by UV-Vis spectrophotometry, using a chemosensor, and compared to traditional ICP-MS analysis. Analytical results showed that the chemosensor provided a visual response in contaminated soils at concentrations of 25 µM and quantitative detection to concentrations of 1 µM using UV-Vis spectrophotometry. This work demonstrates the first reported chemosensor for exchangeable Cu2+ with application to soil systems.


Assuntos
Colorimetria/métodos , Cobre/análise , Poluentes do Solo/análise , Bentonita/química , Cátions , Argila/química , Mineração , Solo , Espectrofotometria
11.
Spectrochim Acta A Mol Biomol Spectrosc ; 224: 117339, 2020 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-31344573

RESUMO

An analytical investigation was carried out to study the treatment and amplification of the spectral signals produced by critical concentrations with high accuracy and precision using two advanced approaches. The factorized-spectrum approach was applied through two novel methods which were: absorptivity centering technique via both: factorized zero order absorption spectrum (ACT-FSD0ΔA) and factorized ratio spectrum (ACT-FSRΔP). The proposed methods were found to be linear in the ranges of (15-100 µg/mL) and (3-40 µg/mL) for ASP and MTO, respectively. Those methods were compared to the methods following the geometrical standard addition approach: ratio H-point standard addition method (RHPSAM) and geometrical induced amplitude modulation (GIAM). The approaches were applied for the determination of the minor component metoclopramide in its mixture with the major component aspirin in the challengeable ratio of (1,90) respectively in a white multicomponent system. The results obtained from the proposed approaches were statistically compared with each other. The methods were validated according to ICH guidelines where the results were found to be within the acceptable limits. The methods were found to be accurate and reliable for the determination of metoclopramide critical concentration besides aspirin concentration. The results of single factor ANOVA analysis indicated that there is no significant difference among the developed methods. These methods provided simple resolution of this binary combination from synthetic mixtures and pharmaceutical preparation and can be conveniently adopted for routine quality control analysis.


Assuntos
Preparações Farmacêuticas/análise , Processamento de Sinais Assistido por Computador , Espectrofotometria/métodos , Aspirina/análise , Aspirina/química , Modelos Lineares , Metoclopramida/análise , Metoclopramida/química , Modelos Químicos , Modelos Estatísticos , Preparações Farmacêuticas/química , Reprodutibilidade dos Testes
12.
Chemosphere ; 239: 124809, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31527008

RESUMO

Honey is a highly nutritious natural product widely produced and consumed by people in Shirak and Syunik regions of Armenia. Unlike Shirak, Syunik is under the impact of mining industry. Since the environmental pollution can adversely impact the safety of honey and entail a probable risk to human health, it is important to evaluate the presence of potentially toxic trace elements in honey samples from both regions and draw comparisons. This study assesses the dietary exposure to trace elements and persistent organic pollutants through the intake of honey for the first time among people in Shirak and Syunik regions. 24-hour dietary recall method was used to investigate the consumption of honey. The presence of seven trace elements (Pb, Cd, As, Hg, Cu, Zn, and Ni) and persistent organic pollutants (hexachlorocyclohexane (HCH), dichlorodiphenyltrichloroethane (DDT) and its metabolites) were determined in honey samples using atomic absorption spectrometry and gas chromatography-mass spectrometry, respectively. In several samples, the concentrations of Cu were above the maximum allowable level. Non-carcinogenic risk values did not exceed the acceptable level, while carcinogenic risk values for Ni and As exceeded the risk level of 10-6 in both regions. Moreover, among the persistent organic pollutants, only the concentration of DDT in honey from Shirak was above the European Union maximum residue level.


Assuntos
Carcinógenos/análise , DDT/análise , Exposição Dietética/análise , Mel/análise , Medição de Risco/métodos , Oligoelementos/análise , Armênia , Poluentes Ambientais/análise , Poluição Ambiental/análise , Mel/toxicidade , Humanos , Metais Pesados/análise , Mineração , Espectrofotometria
13.
J Contemp Dent Pract ; 20(9): 1045-1050, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31797827

RESUMO

AIM: To evaluate the effect of surface sealants containing different filler content on the color stability of microhybrid and nanofilled composite resins. MATERIALS AND METHODS: The materials evaluated as study groups were comprised a nanofilled composite resin (Filtek Ultimate, 3M ESPE) and a microhybrid composite resin (Filtek Z250, 3M ESPE). Forty-five disc-shaped specimens (10 mm × 2 mm) were prepared from each composite resin. Each study group was divided into three subgroups: control, G-Coat Plus, and Fortify Plus (n = 15). The baseline color values (L*a*b*) of each specimen were measured using a spectrophotometer according to the CIE L*a*b* color scale. Then, the specimens were immersed in red wine for a period of 3 hours per day for 15 days (3 hours/day × 15 days). After the immersion period, the color values (L*a*b*) of each specimen were measured again. The ΔL*, Δa*, and Δb* values and the color change value (ΔE) were calculated. The data were statistically analyzed with two-way ANOVA and Duncan tests (p = 0.05). RESULTS: All the composite resin groups demonstrated/indicated much more color changes after immersion in red wine (ΔE > 3.3). The greater ΔE values were observed with the groups applied surface sealants than the control groups (p < 0.05). Fortify Plus further increased the ΔE values of both composite resins than G Coat Plus (p < 0.05). Filtek Ultimate showed higher ΔE values than Filtek Z250 in all the subgroups (p < 0.05). CONCLUSION: The surface sealants regardless of the filler content negatively influenced the color change of the composite resins after immersed in red wine. The microhybrid composite resin had better color stability than the nanofilled composite resin. CLINICAL SIGNIFICANCE: There is no favorable effect of using surface sealants on composite resins to prevent discoloration; besides, the sealants can also increase the color alteration.


Assuntos
Resinas Compostas , Materiais Dentários , Cor , Teste de Materiais , Espectrofotometria , Propriedades de Superfície
14.
Int J Comput Dent ; 22(4): 343-351, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31840142

RESUMO

The aim of this study was to assess the influence of a polarizing filter on the accuracy of dental shade matching using digital photography. A comparison was performed using ΔEab parameters between CIE L*a*b* values obtained from digital images taken under two different conditions (with direct light and with polarized light) and the values given by the dental spectrophotometer SpectroShade Micro, which is considered to be the standard. Color differences (ΔEab) calculated between the parameters recorded with the dental spectrophotometer and polarized photography were below or at the level of the 50:50% acceptability threshold of 2.7 in 23% of the cases. Interdevice agreement found between the dental spectrophotometer and polarized photography exceeded 0.82 for all the three parameters recorded. Digital photography with polarizing filters might be a useful tool for dental shade matching.


Assuntos
Fotografação , Pigmentação em Prótese , Algoritmos , Cor , Planejamento de Prótese Dentária , Humanos , Fotografia Dentária , Espectrofotometria
15.
Phys Chem Chem Phys ; 21(48): 26430-26437, 2019 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-31774088

RESUMO

We explore the influence of the relative position of the methyl substituent on the photophysics of theophylline and theobromine, two molecules that are structurally related to the DNA bases. Using a combination of spectroscopic techniques and quantum mechanical calculations, we show that moving the methyl group from N1 in theophylline to N7 in theobromine causes significant differences in their excited state properties, i.e., it produces pyramidalization of N7 in the excited state of the latter. Paradoxically, this modification seems to have little effect on the structural properties of the cation and the ionization process. It is suggested that similar effects may exist in the excited state properties of DNA bases.


Assuntos
Teobromina/química , Teofilina/química , Xantinas/química , Espectroscopia Fotoeletrônica , Espectrofotometria
16.
J Photochem Photobiol B ; 201: 111639, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31698220

RESUMO

Increasing concerns about health safety, social impacts and fair trade have intensified the industrial interest for using natural products in commercial cosmetic formulations. Several studies are currently focusing on plant extracts, but tropical fruits, such as guava, remain yet unexplored and, consequently, underutilized. This research aims to evaluate the potential for using guava-fruit extract as a photoprotective additive agent for sun cream formulations. The phytochemical screening revealed the presence of flavonoids and tannins and the absence of coumarins. Although the Psidium guajava extract showed a low sun protection factor (SPF) value (1.0), it improved in about 134% the photoprotective result (8.1) of 7.5% 2-ethyl-hexyl methoxycinnamate formulation. Therefore, guava-fruit extract supplementation in the formulation shows the potential to reduce the use of synthetic photoprotectors in about 78.9% from the total synthetic organic filters used to achieve the SPF value of 18. Thus, sun cream supplemented with guava-fruit extract show the potential for minimizing the risk of synthetic agent toxicity, and a 65.8% reduction in the cost of the sunscreen production.


Assuntos
Extratos Vegetais/química , Psidium/química , Protetores Solares/química , Raios Ultravioleta , Composição de Medicamentos , Frutas/química , Frutas/metabolismo , Psidium/metabolismo , Espectrofotometria , Fator de Proteção Solar
17.
An Bras Dermatol ; 94(5): 561-566, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31777357

RESUMO

BACKGROUND: Rubeosis faciei diabeticorum is a persistent facial erythema in patients with diabetes mellitus. The actual pathogenesis has not been studied. However, it is speculated to be a cutaneous diabetic microangiopathy. OBJECTIVE: Examine the correlation between the severity of facial erythema and the possible causes of microvascular diabetic complications, namely oxidative stress, hyperglycemia, and cutaneous accumulation of advanced glycation end-products . METHODS: Patients diagnosed with Type 2 diabetes mellitus (n=32) were enrolled in the study. The facial erythema index was measured using the Mexameter MX18; cutaneous accumulation of advanced glycation end-products was estimated by measuring skin auto fluorescence with the AGE Reader (DiagnOptics Technologies B.V. - Groningen, Netherlands). Glycated haemoglobin, total antioxidant status, and malondialdehyde were measured in blood by TBARS assay. The correlation between the selected variables was assessed by Spearman's rank test; p≤0.05 was considered statistically significant. RESULTS: There was a statistically significant correlation between total antioxidant status and the facial erythema index (ρ=0.398, p=0.024). Malondialdehyde, skin autofluorescence, glycated haemoglobin, body mass index, duration of diabetes, and age did not demonstrate statistically significant correlation with the facial erythema index. STUDY LIMITATIONS: This is an observational study. Elevation of total antioxidant status could have been caused by several factors that might have also influenced the development of rubeosis faciei, including hyperbilirubinemia and hyperuricemia. CONCLUSIONS: The results contradicted expectations. Total antioxidant status correlated positively with facial erythema index; however, there was no correlation with oxidative stress and skin autofluorescence. Further investigations should be conducted to reveal the cause of total antioxidant status elevation in patients with rubeosis faciei.


Assuntos
Angiopatias Diabéticas/metabolismo , Eritema/metabolismo , Dermatoses Faciais/metabolismo , Estresse Oxidativo , Adulto , Idoso , Antioxidantes/análise , Índice de Massa Corporal , Diabetes Mellitus Tipo 2/complicações , Diabetes Mellitus Tipo 2/metabolismo , Angiopatias Diabéticas/complicações , Eritema/etiologia , Dermatoses Faciais/etiologia , Feminino , Fluorescência , Hemoglobina A Glicada/análise , Humanos , Masculino , Malondialdeído/sangue , Pessoa de Meia-Idade , Valores de Referência , Espectrofotometria , Estatísticas não Paramétricas
18.
Phys Chem Chem Phys ; 21(43): 23931-23942, 2019 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-31661536

RESUMO

There is a growing body of experimental work showing that protein aggregates associated with amyloid fibrils feature intrinsic fluorescence. In order to understand the microscopic origin of this behavior observed in non-aromatic aggregates of peptides and proteins, we conducted a combined experimental and computational study on the optical properties of amyloid-derived oligopeptides in the near-UV region. We have focused on a few model systems having charged termini (zwitterionic) or acetylated termini. For the zwitterionic system, we were able to simulate the longer tail absorption in the near UV (250-350 nm), supporting the experimental results in terms of excitation spectra. We analyzed the optical excitations responsible for the low-energy absorption and found a large role played by charge-transfer states around the termini. These charge-transfer excitations are very sensitive to the conformation of the peptide and in realistic fibrils may involve inter and intra chain charge reorganization.


Assuntos
Proteínas Amiloidogênicas/química , Proteínas Amiloidogênicas/metabolismo , Teoria da Densidade Funcional , Microscopia de Força Atômica , Espectrofotometria , Termodinâmica
19.
Adv Exp Med Biol ; 1222: 27-35, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31559568

RESUMO

Oxidative stress underlies both obstructive sleep apnea (OSA) and atherosclerosis. The aim of the study was to assess the markers of oxidative stress in plasma at different stages of OSA in non-smoking obese Caucasian males aged 41-60, with normal oral glucose tolerance test. All patients were subjected to clinical and polysomnographic examinations. The stage of OSA severity was set according to the following criteria of the apnea-hypopnea index (AHI): AHI < 5/h - no disease (OSA-0; n = 26), AHI 5-15/h - mild disease (OSA-1; n = 26), AHI 16-30/h - moderate disease (OSA-2: n = 27), and AHI > 30/h obstructive episodes per hour - severe disease (OSA-3; n = 27). Plasma total antioxidant status (TAS) and thiobarbituric acid-reacting substances (TBARS), reflecting the level of lipid peroxides, were determined spectrophotometrically. We found that TAS decreased and TBARS increased significantly from OSA-0 to OSA-3. We conclude that the oxidative stress markers are conducive to setting the severity of OSA in normoglycemic patients.


Assuntos
Biomarcadores/sangue , Obesidade , Estresse Oxidativo/fisiologia , Apneia Obstrutiva do Sono/sangue , Adulto , Antioxidantes/análise , Teste de Tolerância a Glucose , Humanos , Peróxidos Lipídicos/análise , Masculino , Pessoa de Meia-Idade , Polissonografia , Índice de Gravidade de Doença , Espectrofotometria , Substâncias Reativas com Ácido Tiobarbitúrico/análise
20.
Photochem Photobiol Sci ; 18(10): 2539-2552, 2019 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-31528964

RESUMO

Cyanobacteriochromes (CBCRs) are photosensitive proteins that are distantly related to the phytochrome family of photoreceptors and, like phytochromes, exhibit photoactivity initiated by the excited-state photoisomerization of a covalently bound bilin chromophore. The canonical red/green photoswitching sub-family is the most studied class of CBCRs studied to date. Recently, a comparative study of the ultrafast (100 fs-10 ns) forward photodynamics of nine red/green photoswitching CBCR domains isolated from Nostoc punctiforme were reported (S. M. Gottlieb, P. W. Kim, C.-W. Chang, S. J. Hanke, R. J. Hayer, N. C. Rockwell, S. S. Martin, J. C. Lagarias and D. S. Larsen, Conservation and Diversity in the Primary Forward Photodynamics of Red/Green Cyanobacteriochromes, Biochemistry, 2015, 54, 1028-1042). We extend this study by characterizing the secondary (10 ns-1 ms) forward photodynamics of eight red/green photoswitching CBCRs from N. punctiforme with broadband time-resolved absorption spectroscopy. We demonstrate that the dynamics of these representative red/green CBCRs can be separated into two coexisting pathways involving a photoactive pathway that is successful in generating the terminal light-adapted 15EPg population and an unsuccessful pathway that stalls after generating a meta-stable Lumi-Of intermediate. The photoactive pathway evolves through a similar mechanism from excitation of the dark-adapted 15ZPr state to generate a far-red absorbing Lumi-Rf and then via a succession of blue-shifting photointermediates to ultimately generate the 15EPg state. This suggests a steady deviation from planarity of the bilin chromophore during the dynamics. While, the general mechanism for this evolution is conserved among these CBCBs, the timescales of these dynamics deviate significantly. Only half of the characterized CBCRs exhibit the unproductive pathways due to photoexcitation of dark-adapted 15ZPo sub-population that upon photoexcitation generates a meta-stable Lumi-Of intermediate, which eventually decays back to the 15ZPo subpopulation. 15ZPo is ascribed the horizontal Asp657 configuration that disrupts H-bonding with the chromophore in the dark-adapted state; its presence can be identified via enhanced absorption of high-energy tail of the electronic absorption spectrum.


Assuntos
Proteínas de Bactérias/química , Nostoc/metabolismo , Fotorreceptores Microbianos/química , Proteínas de Bactérias/metabolismo , Luz , Fotorreceptores Microbianos/metabolismo , Estrutura Terciária de Proteína , Espectrofotometria
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