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1.
Molecules ; 26(15)2021 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-34361707

RESUMO

The mechanism by which proteins are solvated in hydrated ionic liquids remains an open question. Herein, the photoexcitation dynamics of photoactive yellow protein dissolved in hydrated choline dihydrogen phosphate (Hy[ch][dhp]) were studied by transient absorption and transient grating spectroscopy. The photocyclic reaction of the protein in Hy[ch][dhp] was similar to that observed in the buffer solution, as confirmed by transient absorption spectroscopy. However, the structural change of the protein during the photocycle in Hy[ch][dhp] was found to be different from that observed in the buffer solution. The known change in the diffusion coefficient of the protein was apparently suppressed in high concentrations of [ch][dhp], plausibly due to stabilization of the secondary structure.


Assuntos
Proteínas de Bactérias/química , Líquidos Iônicos/química , Fosforilcolina/química , Fotorreceptores Microbianos/química , Água/química , Tampões (Química) , Difusão , Luz , Solubilidade , Análise Espectral/métodos
2.
J Synchrotron Radiat ; 28(Pt 4): 1237-1244, 2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-34212889

RESUMO

During the COVID-19 pandemic, synchrotron beamlines were forced to limit user access. Performing routine measurements became a challenge. At the Life Science X-ray Scattering (LiX) beamline, new instrumentation and mail-in protocols have been developed to remove the access barrier to solution scattering measurements. Our efforts took advantage of existing instrumentation and coincided with the larger effort at NSLS-II to support remote measurements. Given the limited staff-user interaction for mail-in measurements, additional software tools have been developed to ensure data quality, to automate the adjustments in data processing, as users would otherwise rely on the experience of the beamline staff, and produce a summary of the initial assessments of the data. This report describes the details of these developments.


Assuntos
Espalhamento a Baixo Ângulo , Soluções/efeitos da radiação , Síncrotrons/instrumentação , Difração de Raios X/instrumentação , Tampões (Química) , COVID-19 , Coleta de Dados , Conjuntos de Dados como Assunto , Processamento Eletrônico de Dados , Pandemias , Robótica , SARS-CoV-2 , Software , Manejo de Espécimes , Água
3.
Int J Pharm ; 605: 120857, 2021 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-34229072

RESUMO

There are many hurdles in the development of generic formulations. In vitro biopredictive dissolution conditions together with alternative in vitro - in vivo relationship (IVIVR) approaches can be a powerful tool to support the development of such formulations. In this study, we hypothesized that the release profile of enteric coated (EC) formulations of pantoprazole in physiologically relevant bicarbonate buffer (BCB) would detect possible performance differences between test and reference formulations resulting in more accurate IVIVR results and predictability when compared to a pharmacopeial dissolution test. We correlated the in vitro performance of test and reference formulations (both in BCB and pharmacopeial phosphate buffer) with the in vivo data from a failed bioequivalence study. Test and reference formulations of EC pantoprazole tablets passed the USP dissolution criteria. However, they failed statistical similarity in vitro both in compendial and BCB. Bicarbonate buffer was additionally more discriminative while being more physiologically relevant. Having BCB as an additional test to evaluate EC products in vitro might improve the comparison of formulations. This can de-risk the development of generic EC formulations.


Assuntos
Química Farmacêutica , Tampões (Química) , Concentração de Íons de Hidrogênio , Pantoprazol , Solubilidade , Comprimidos , Comprimidos com Revestimento Entérico
4.
J Chromatogr A ; 1652: 462077, 2021 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-34214832

RESUMO

Stepwise change between low and high salt concentration buffers of the same pH results in pH transition, the length of which was demonstrated to be proportional to the quantity of ion-exchange groups present on the matrix. In this work, we analyzed the effect of the ligand type, density, and buffer concentration on the pH transition shape for typical ion-exchange groups (QA, DEAE, SO3, and COOH) and ligands acting as metal-chelators, such as IDA, TAEA, and EDA. It was demonstrated that pH transition can occur either as a chromatographic or flat-top peak. pH transition peaks were evaluated by their length, height, and peak center parameters. While no parameter can describe the ligand density accurately with a single linear correlation for both peak types, all parameters can be used for the description of one peak type. Peak length and height exhibited the same accuracy, while their sensitivity depended on the pH transition shape: length being more sensitive for the flat-top peaks, while height for the chromatographic peaks. pH height can be obtained faster, at lower elution volume, and seems to be more suitable for the determination of low amounts of ligand, when typically chromatographic peak type pH transitions occur.


Assuntos
Técnicas de Química Analítica , Ligantes , Polímeros , Tampões (Química) , Quelantes/química , Técnicas de Química Analítica/métodos , Cromatografia Líquida , Emulsões/química , Concentração de Íons de Hidrogênio , Polímeros/química
5.
J Chromatogr A ; 1651: 462257, 2021 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-34090057

RESUMO

This study assesses the potential of using ionic liquids (ILs) as mobile phase additives to control the retention mechanism of four cytostatic drugs: doxorubicin hydrochloride (DOX), epirubicin hydrochloride (EPI), daunorubicin hydrochloride (DAU) and idarubicin hydrochloride (IDA). Chromatographic separations were performed on a C18 analytical column (Discovery C18 150 × 4.6 mm, 5 µm) using six IL anions and four methyl-substituted IL cations with different alkyl chain lengths (alone or with the additional methyl group on the aromatic ring), or with an allyl group added as a cationic substituent. Thus, a total of 17 different ILs were assessed. The aqueous formic acid solution and phosphate buffer were used to compare how mobile phase composition affected the behavior of the analyzed cytostatic agents in the presence of ILs. In addition, the impacts of IL concentration, phosphate buffer concentration, and phosphate buffer pH on the final results were also considered. The ability to change analyte retention without negatively impacting peak shape or analytical efficiency was also controlled via the tailing factor and number of theoretical plates. Based on the results, the tested ILs were classified as either effective or ineffective mobile phase additives for separation of anthracyclines and identification by LC-FL technique.


Assuntos
Cromatografia Líquida/métodos , Citostáticos/análise , Líquidos Iônicos/química , Dióxido de Silício/química , Ânions , Antraciclinas/análise , Tampões (Química) , Cátions , Cromatografia de Fase Reversa/métodos , Fosfatos/química , Fatores de Tempo
6.
Ultrason Sonochem ; 76: 105609, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34157567

RESUMO

A novel method of thermoultrasound-assisted plasma functionalized buffer (PFB) for decontaminating grass carp was evaluated using the Box-Behnken design (BBD) with processing variables including PFB generating voltage (PV), ultrasound treatment time (UT) and temperature (TP). The predicted models were found to be significant (p < 0.05) and displayed sufficient fitness with experimental data as indicated by non-significant (p > 0.05) lack of fit and high coefficient of determination (R2≥0.97) values. The optimum decontamination conditions for the responses of S. putrefaciens and S. Typhimurium were PV of 66 V, UT of 14.90 min and TP of 60 ℃, achieving reductions of 4.40 and 3.97 log CFU/g, respectively, with a desirability of 0.998. Among the variables, temperature presented higher significance for inactivating bacteria and the production of volatile basic nitrogen and lipid peroxidation under the optimized conditions were within the limits of freshness for grass carp. Additionally, the effects of PFB and the optimized thermoultrasound-assisted PFB decontamination were mild on the microstructure of grass carp with slight ruptures and loose myofibril structures, indicating the potential of thermoultrasound-assisted PFB for seafood products decontamination with reduced processing time.


Assuntos
Carpas/microbiologia , Gases em Plasma/química , Gases em Plasma/farmacologia , Salmonella typhimurium/efeitos dos fármacos , Shewanella putrefaciens/efeitos dos fármacos , Temperatura , Ondas Ultrassônicas , Animais , Tampões (Química) , Microbiologia de Alimentos , Viabilidade Microbiana/efeitos dos fármacos , Salmonella typhimurium/fisiologia , Shewanella putrefaciens/fisiologia
7.
J Chromatogr A ; 1651: 462294, 2021 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-34098249

RESUMO

Few articles are reported for the simultaneous separation and sensitive detection of the kynurenine pathway (KP) metabolites. This work describes a capillary electrochromatography-mass spectrometry (CEC-MS) method using acrylamido-2-methyl-1-propanesulfonic acid (AMPS) functionalized stationary phase. The AMPS column was prepared by first performing silanization of bare silica with gamma-maps, followed by polymerization with AMPS. The CEC-MS/MS methods were established for six upstream and three downstream KP metabolites. The simultaneous separation of all nine KP metabolites is achieved without derivatization for the first time in the open literature. Numerous parameters such as pH and the concentration of background electrolyte, the concentration of the polymerizable AMPS monomer, column length, field strength, and internal pressure were all tested to optimize the separation of multiple KP metabolites. A baseline separation of six upstream metabolites, namely tryptophan (TRP), kynurenine (KYN), 3-hydroxykynurenine (HKYN), kynurenic acid (KA), anthranilic acid (AA), and xanthurenic acid (XA), was possible at pH 9.25 within 26 min. Separation of six downstream and related metabolites, namely: tryptamine (TRPM), hydroxy­tryptophan (HTRP), hydroxyindole-3 acetic acid (HIAA), 3-hydroxyanthranilic acid (3-HAA), picolinic acid (PA), and quinolinic acid (QA), was achieved at pH 9.75 in 30 min. However, the challenging simultaneous separation of all nine KP metabolites was only accomplished by increasing the column length and simultaneous application of internal pressure and voltage in 114 min. Quantitation of KP metabolites in commercial human plasma was carried out, and endogenous concentration of five KP metabolites was validated. The experimental limit of quantitation ranges from 100 to 10,000 nM (S/N = 8-832, respectively), whereas the experimental limit of detection ranges from 31 to 1000 nM (S/N = 2-16, respectively). Levels of five major KP metabolites, namely TRP, KYN, KA, AA, and QA, and their ratios in patient plasma samples previously screened for inflammatory biomarkers [C-reactive protein (CRP) and tumor necrosis factor-alpha (TNF-α)] was measured. Pairs of the level of metabolites with significant positive correlation were statistically evaluated.


Assuntos
Eletrocromatografia Capilar/métodos , Cinurenina/metabolismo , Redes e Vias Metabólicas , Metaboloma , Ácidos Alcanossulfônicos/química , Tampões (Química) , Calibragem , Eletricidade , Humanos , Concentração de Íons de Hidrogênio , Cinurenina/sangue , Limite de Detecção , Modelos Lineares , Pressão , Ácido Quinolínico/metabolismo , Padrões de Referência , Reprodutibilidade dos Testes , Espectrometria de Massas em Tandem/métodos
8.
J Chromatogr A ; 1651: 462298, 2021 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-34111678

RESUMO

In this work, novel stationary phase coatings by zeolite SiO2NPs coupled with ß-cyclodextrin (ß-CD) or ß-CD/L-phenylalanine were developed for chiral open-tubular capillary electrochromatography (OT-CEC). The OT columns were prepared taking advantage of the strong adhesion of polydopamine in one-step method. Scanning electron micrography and electroosmotic flow were used to characterize the prepared single/dual-selector OT columns. Chiral separation of four chiral analytes (catechin/epicatechin, ephedrine/pseudoephedrine, ritodrine and salbutamol) was carried out in order to evaluate the performance of the prepared columns in OT-CEC with amperometric detection system. In terms of migration time, peak area, resolution, and selectivity factor of catechin/epicatechin and salbutamol, the run-to-run, day-to-day, and column-to-column repeatability were within 8.9%. Under the optimum conditions, the developed methods were applied for the analyses of Chinese herbal medicine Catechu herbs and salbutamol aerosol samples.


Assuntos
Eletrocromatografia Capilar/métodos , Nanopartículas/química , Dióxido de Silício/química , Zeolitas/química , Tampões (Química) , Concentração de Íons de Hidrogênio , Estereoisomerismo , beta-Ciclodextrinas/química
9.
J Chromatogr A ; 1650: 462247, 2021 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-34087520

RESUMO

The adsorptive loss of acidic analytes in liquid chromatography was investigated using metal frits. Repetitive injections of acidic small molecules or an oligonucleotide were made on individual 2.1 or 4.6 mm i.d. column frits. Losses were observed for adenosine 5'-(α,ß-methylene) diphosphate, 2-pyridinol 1-oxide and the 25-mer phosphorothioate oligonucleotide Trecovirsen (GEM91) on stainless steel and titanium frits. Analyte adsorption was greatest at acidic pH due to the positive charge on the metal oxide surface. Analyte recovery increased when a series of injections was performed; this effect is known as sample conditioning. Nearly complete recovery was achieved when the metal adsorptive sites were saturated with the analyte. A similar effect was achieved by conditioning the frits with phosphoric, citric or etidronic acids, or their buffered solutions. These procedures can be utilized to mitigate analyte loss. However, the effect is temporary, as the conditioning agent is gradually removed by the running mobile phase. Metal frits modified with hybrid organic/inorganic surface technology were shown to mitigate analyte-to-metal surface interactions and improve recovery of acidic analytes. Quantitative recovery of a 15-35 mer oligodeoxythymidine mixture was achieved using column hardware modified with hybrid surface technology, without a need for column conditioning prior to analysis.


Assuntos
Cromatografia Líquida , Metais , Adsorção , Tampões (Química) , Cromatografia Líquida/métodos , Cromatografia Líquida/normas , Ácido Cítrico/química , Ácido Etidrônico/química , Indicadores e Reagentes , Metais/química , Ácidos Fosfóricos/química , Aço Inoxidável/química , Propriedades de Superfície , Titânio/química
10.
J Biol Chem ; 297(1): 100775, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-34022218

RESUMO

Cellular pyruvate is an essential metabolite at the crossroads of glycolysis and oxidative phosphorylation, capable of supporting fermentative glycolysis by reduction to lactate mediated by lactate dehydrogenase (LDH) among other functions. Several inherited diseases of mitochondrial metabolism impact extracellular (plasma) pyruvate concentrations, and [1-13C]pyruvate infusion is used in isotope-labeled metabolic tracing studies, including hyperpolarized magnetic resonance spectroscopic imaging. However, how these extracellular pyruvate sources impact intracellular metabolism is not clear. Herein, we examined the effects of excess exogenous pyruvate on intracellular LDH activity, extracellular acidification rates (ECARs) as a measure of lactate production, and hyperpolarized [1-13C]pyruvate-to-[1-13C]lactate conversion rates across a panel of tumor and normal cells. Combined LDH activity and LDHB/LDHA expression analysis intimated various heterotetrameric isoforms comprising LDHA and LDHB in tumor cells, not only canonical LDHA. Millimolar concentrations of exogenous pyruvate induced substrate inhibition of LDH activity in both enzymatic assays ex vivo and in live cells, abrogated glycolytic ECAR, and inhibited hyperpolarized [1-13C]pyruvate-to-[1-13C]lactate conversion rates in cellulo. Of importance, the extent of exogenous pyruvate-induced inhibition of LDH and glycolytic ECAR in live cells was highly dependent on pyruvate influx, functionally mediated by monocarboxylate transporter-1 localized to the plasma membrane. These data provided evidence that highly concentrated bolus injections of pyruvate in vivo may transiently inhibit LDH activity in a tissue type- and monocarboxylate transporter-1-dependent manner. Maintaining plasma pyruvate at submillimolar concentrations could potentially minimize transient metabolic perturbations, improve pyruvate therapy, and enhance quantification of metabolic studies, including hyperpolarized [1-13C]pyruvate magnetic resonance spectroscopic imaging and stable isotope tracer experiments.


Assuntos
L-Lactato Desidrogenase/antagonistas & inibidores , Transportadores de Ácidos Monocarboxílicos/metabolismo , Ácido Pirúvico/farmacologia , Simportadores/metabolismo , Ácidos/metabolismo , Tampões (Química) , Isótopos de Carbono , Extratos Celulares , Linhagem Celular Tumoral , Membrana Celular/efeitos dos fármacos , Membrana Celular/metabolismo , Espaço Extracelular/química , Glicólise/efeitos dos fármacos , Humanos , Concentração Inibidora 50 , Cinética , L-Lactato Desidrogenase/metabolismo , Ácido Láctico/biossíntese , Especificidade por Substrato/efeitos dos fármacos
11.
J Chromatogr A ; 1648: 462182, 2021 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-33979757

RESUMO

In this work, two mixed-mode columns from a different manufacturers and one marketed as a reversed-phase column were characterized and compared in the terms of their interaction abilities, retentivity, peak symmetry, and applicability for peptide separation. All the tested columns contain octadecyl ligand and positively charged modifier, i.e. pyridyl group for the reversed-phase column XSelect CSH C18, quaternary alkylamine for mixed-mode column Atlantis PREMIER BEH C18 AX, and permanently charged moiety (details not available from the manufacturer) for mixed-mode column Luna Omega PS C18. For detailed characterization and comparison of their interaction potential, several approaches were used. First, a simple Walters test was performed to estimate hydrophobic and silanophilic interactions of the tested columns. The highest values of both parameters were observed for column Atlantis PREMIER BEH C18 AX. To investigate the effect of pH and buffer concentration on retention, mobile phases composed of acetonitrile and buffer (ammonium formate, pH 3.0; ammonium acetate pH 4.7 and pH 6.9) in various concentrations (5mM; 10mM; 15mM and 20mM) were used. The analysis of permanently charged compounds was used to describe the electrostatic interaction abilities of the stationary phases. The most significant contribution of electrostatic interactions to the retention was observed for Atlantis PREMIER BEH C18 AX column in the mobile phase with buffer of pH 3.0. A set of ten dipeptides, three pentapeptides and one octapeptide was used to investigate the effects of pH and buffer concentration on retention and peak symmetry. Each of the tested columns provides the optimal peak shape under different buffer pH and concentration. The gradient separation of the 14 tested peptides was used to verify the application potential of the tested columns for peptide separation. The best separation was achieved within 4 minutes on column Atlantis PREMIER BEH C18 AX.


Assuntos
Cromatografia de Fase Reversa/instrumentação , Peptídeos/isolamento & purificação , Tampões (Química) , Concentração de Íons de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas
12.
Food Chem ; 358: 129763, 2021 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-34000688

RESUMO

This work reports the electrochemical detection of bisphenol A (BPA) using a novel and sensitive electrochemical sensor based on the Cu functionalized SBA-15 like periodic mesoporous organosilica-ionic liquid composite modified glassy carbon electrode (Cu@TU-PMO/IL/GCE). The structural morphology of Cu@TU-PMO is characterized by X-ray powder diffraction (XRD), energy dispersive X-ray analysis (EDX), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), Field emission scanning electron microscopy (FE-SEM), and Brunauer-Emmett-Teller (BET). The catalytic activity of the modified electrode toward oxidation of BPA was interrogated with cyclic voltammetry (CV) and differential pulse voltammetry (DPV) in phosphate buffer solution (pH 7.0) using the fabricated sensor. The electrochemical detection of the analyte was carried out at a neutral pH and the scan rate studies revealed that the sensor was stable. Under the optimal conditions, a linear range from 5.0 nM to 2.0 µM and 4.0 to 500 µM for detecting BPA was observed with a detection limit of 1.5 nM (S/N = 3). The sensor was applied to detect BPA in tap and seawater samples, and the accuracy of the results was validated by high-performance liquid chromatography (HPLC). The proposed method provides a powerful tool for the rapid and sensitive detection of BPA in environmental samples.


Assuntos
Compostos Benzidrílicos/análise , Técnicas Eletroquímicas/instrumentação , Técnicas Eletroquímicas/métodos , Fenóis/análise , Tampões (Química) , Carbono/química , Cobre/química , Eletrodos , Concentração de Íons de Hidrogênio , Líquidos Iônicos/química , Limite de Detecção , Microscopia Eletrônica de Transmissão , Oxirredução , Fosfatos/química , Dióxido de Silício , Espectroscopia de Infravermelho com Transformada de Fourier , Poluentes Químicos da Água/análise , Difração de Raios X
13.
Sci Rep ; 11(1): 9387, 2021 04 30.
Artigo em Inglês | MEDLINE | ID: mdl-33931684

RESUMO

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), calls for prompt and accurate diagnosis and rapid turnaround time for test results to limit transmission. Here, we evaluated two independent molecular assays, the Biomeme SARS-CoV-2 test, and the Precision Biomonitoring TripleLock SARS-CoV-2 test on a field-deployable point-of-care real-time PCR instrument, Franklin three9, in combination with Biomeme M1 Sample Prep Cartridge Kit for RNA 2.0 (M1) manual extraction system for rapid, specific, and sensitive detection of SARS-COV-2 in cell culture, human, and animal clinical samples. The Biomeme SARS-CoV-2 assay, which simultaneously detects two viral targets, the orf1ab and S genes, and the Precision Biomonitoring TripleLock SARS-CoV-2 assay that targets the 5' untranslated region (5' UTR) and the envelope (E) gene of SARS-CoV-2 were highly sensitive and detected as low as 15 SARS-CoV-2 genome copies per reaction. In addition, the two assays were specific and showed no cross-reactivity with Middle Eastern respiratory syndrome coronavirus (MERS-CoV), infectious bronchitis virus (IBV), porcine epidemic diarrhea virus (PEDV), transmissible gastroenteritis (TGE) virus, and other common human respiratory viruses and bacterial pathogens. Also, both assays were highly reproducible across different operators and instruments. When used to test animal samples, both assays equally detected SARS-CoV-2 genetic materials in the swabs from SARS-CoV-2-infected hamsters. The M1 lysis buffer completely inactivated SARS-CoV-2 within 10 min at room temperature enabling safe handling of clinical samples. Collectively, these results show that the Biomeme and Precision Biomonitoring TripleLock SARS-CoV-2 mobile testing platforms could reliably and promptly detect SARS-CoV-2 in both human and animal clinical samples in approximately an hour and can be used in remote areas or health care settings not traditionally serviced by a microbiology laboratory.


Assuntos
COVID-19/diagnóstico , Reação em Cadeia da Polimerase em Tempo Real/métodos , SARS-CoV-2/isolamento & purificação , Animais , Tampões (Química) , Cricetinae , Humanos , Aplicativos Móveis , Kit de Reagentes para Diagnóstico , SARS-CoV-2/genética , Sensibilidade e Especificidade , Fatores de Tempo
14.
Anal Chim Acta ; 1166: 338547, 2021 Jun 29.
Artigo em Inglês | MEDLINE | ID: mdl-34022999

RESUMO

Studying the role of buffers in impedance spectroscopy is a relatively unexplored area. We demonstrate a special class of biologically relevant buffers known as Good's zwitterionic buffers that show improved performance over standard electrolyte buffers (e.g. PBS) currently widely used in impedance spectroscopy measurements of bacterial suspensions. Our theoretical and experimental comparisons of conductivity of classical and zwitterionic buffers at various different concentrations show that ion-ion interaction effects are significantly higher in zwitterionic buffers as compared to classical buffers at the concentrations at which they are used. This and the fact that zwitterions have larger sizes leads to the lowering of their conductivity which significantly improves their impedance sensing ability. We illustrate through an example of heat-induced ionic release in model S. typhi and S. aureus bacteria that having a low conductivity buffer is indeed beneficial for biological impedance measurements. In fact, the best buffer for impedance studies can be chosen solely based on their electrical properties as long as they are also biologically compatible. This gives Good's zwitterionic buffers an edge over conventional media as they satisfy both these criteria.


Assuntos
Espectroscopia Dielétrica , Staphylococcus aureus , Tampões (Química) , Condutividade Elétrica , Eletrólitos
15.
ACS Appl Mater Interfaces ; 13(17): 19625-19632, 2021 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-33886270

RESUMO

Hen egg white lysozyme (HEWL) is frequently applied as a model protein for research on protein folding, unfolding, and fibrillization identified by featured fluorescent probes. Here, a series of hydrophilic, pH-sensitive tetraarylethene (TAE)-type AIEgens are synthesized via a geminal cross-coupling (GCC) reaction and evaluated for their capabilities of fluorescence sensing and super-resolution localization imaging of HEWL fibrils. With superior optical and sensing properties, the selected TAE-type AIEgen probe is weakly emissive in aqueous media, without dependence on the pH value and buffer concentration, but exhibits "turn-on" fluorescence upon interaction with HEWL amyloid fibrils in a spontaneous and reversible way that just meets the requirement of fluorescence random switching for super-resolution imaging. The selected probe has the strongest fluorescence response to HEWL amyloid fibrils exhibiting a limit of detection of 0.59 nmol/L and enables super-resolution fluorescence imaging of amyloid aggregates with a high resolution of 40 nm.


Assuntos
Amiloide/química , Microscopia de Fluorescência/métodos , Muramidase/química , Tampões (Química) , Corantes Fluorescentes , Concentração de Íons de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas
16.
Lett Appl Microbiol ; 73(2): 159-167, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-33894066

RESUMO

High pressure homogenization (HPH) offers new opportunities for food pasteurization/sterilization. Escherichia coli and Staphylococcus aureus suspended in phosphate buffered saline (PBS) buffer, milk and apple juice at initial concentration of ~106 log10 CFU per ml were subjected to HPH treatments up to 200 MPa with inlet temperatures at 4-40°C. After HPH at 200 MPa with the inlet temperature at 40°C, the count of E. coli suspended in PBS, milk and apple juice reduced by 3·42, 3·67 and 3·19 log10 CFU per ml respectively while the count of S. aureus decreased by 2·21, 1·02 and 2·33 log10 CFU per ml respectively suggesting that S. aureus was more resistant. The inactivation data were well fitted by the polynomial equation. Milk could provide a protective effect for S. aureus against HPH. After HPH at 200 MPa with the inlet temperature at 20°C, the cell structure of E. coli was destroyed, while no obvious damages were found for S. aureus.


Assuntos
Escherichia coli O157/crescimento & desenvolvimento , Sucos de Frutas e Vegetais/microbiologia , Leite/microbiologia , Pasteurização/métodos , Staphylococcus aureus/crescimento & desenvolvimento , Animais , Tampões (Química) , Contagem de Colônia Microbiana , Microbiologia de Alimentos , Conservação de Alimentos , Malus/microbiologia , Microscopia Eletrônica , Fosfatos , Pressão , Solução Salina , Temperatura
17.
Toxins (Basel) ; 13(4)2021 03 27.
Artigo em Inglês | MEDLINE | ID: mdl-33801738

RESUMO

In the attempt to improve the purification yield of native toxin A (TcdA) and toxin B (TcdB) from Clostridioides difficile (C. difficile), we systematically evaluated culture parameters for their influence on toxin production. In this study, we showed that culturing C. difficile in a tryptone-yeast extract medium buffered in PBS (pH 7.5) that contained 5 mM ZnCl2 and 10 mM glucose supported the highest TcdB production, measured by the sandwich ELISA. These culture conditions were scalable into 5 L and 15 L dialysis tube cultures, and we were able to reach a TcdB concentration of 29.5 µg/mL of culture. Furthermore, we established a purification protocol for TcdA and TcdB using FPLC column chromatography, reaching purities of >99% for both toxins with a yield around 25% relative to the starting material. Finally, by screening the melting temperatures of TcdA and TcdB in various buffer conditions using differential scanning fluorimetry, we found optimal conditions for improving the protein stability during storage. The results of this study present a complete protocol for obtaining high amounts of highly purified native TcdA and TcdB from C. difficile.


Assuntos
Proteínas de Bactérias/isolamento & purificação , Toxinas Bacterianas/isolamento & purificação , Técnicas Bacteriológicas , Clostridioides difficile/metabolismo , Enterotoxinas/isolamento & purificação , Tampões (Química) , Cromatografia por Troca Iônica , Clostridioides difficile/crescimento & desenvolvimento , Clostridioides difficile/patogenicidade , Meios de Cultura/metabolismo , Concentração de Íons de Hidrogênio , Estabilidade Proteica
18.
Nutrients ; 13(3)2021 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-33804015

RESUMO

BACKGROUND: No study has explored the limitations of current long-term management of hyperkalemia (HK) in outpatient CKD clinics. METHODS: We evaluated the association between current therapeutic options and control of serum K (sK) during 12-month follow up in ND-CKD patients stratified in four groups by HK (sK ≥ 5.0 mEq/L) at baseline and month 12: Absent (no-no), Resolving (yes-no), New Onset (no-yes), Persistent (yes-yes). RESULTS: We studied 562 patients (age 66.2 ± 14.5 y; 61% males; eGFR 39.8 ± 21.8 mL/min/1.73 m2, RAASI 76.2%). HK was "absent" in 50.7%, "resolving" in 15.6%, "new onset" in 16.6%, and "persistent" in 17.1%. Twenty-four hour urinary measurements testified adherence to nutritional recommendations in the four groups at either visit. We detected increased prescription from baseline to month 12 of bicarbonate supplements (from 5.0 to 14.1%, p < 0.0001), K-binders (from 2.0 to 7.7%, p < 0.0001), and non-K sparing diuretics (from 34.3 to 41.5%, p < 0.001); these changes were consistent across groups. Similar results were obtained when using higher sK level (≥5.5 mEq/L) to stratify patients. Mixed-effects regression analysis showed that higher sK over time was associated with eGFR < 60, diabetes, lower serum bicarbonate, lower use of non-K sparing diuretics, bicarbonate supplementation, and K-binder use. Treatment-by-time interaction showed that sK decreased in HK patients given bicarbonate (p = 0.003) and K-binders (p = 0.005). CONCLUSIONS: This observational study discloses that one-third of ND-CKD patients under nephrology care remain with or develop HK during a 12-month period despite low K intake and increased use of sK-lowering drugs.


Assuntos
Bicarbonatos/uso terapêutico , Diuréticos/uso terapêutico , Hiperpotassemia/complicações , Hiperpotassemia/tratamento farmacológico , Insuficiência Renal Crônica/complicações , Idoso , Tampões (Química) , Feminino , Seguimentos , Humanos , Estudos Longitudinais , Masculino , Pessoa de Meia-Idade , Nefrologia , Potássio/sangue
19.
Pediatr Dent ; 43(2): 88-94, 2021 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-33892831

RESUMO

Purpose: Buffered local anesthetics offer an alternative to conventional, unbuffered anesthetic formulations; however, evidence about their use in children is scant. The purpose of this study was to determine the anesthetic and physiologic differences associated with the use of buffered one percent and unbuffered two percent lidocaine (both with 1:100,000 epinephrine) in children. Methods: In this randomized, double-blinded, crossover study, 25 children ages 10 to 12 years old received two inferior alveolar never blocks, at least one week apart, randomized to alternating sequences of two drug formulations: (1) formula A-three mL buffered one percent lidocaine (i.e., including 0.3 mL of 8.4 percent sodium bicarbonate); or (2) formula B-three mL unbuffered two percent lidocaine. Primary outcomes were mean blood lidocaine levels (15 minutes post-injection), timing of clinical signs onset, response to pain on injection, and duration of anesthesia. Analyses relied upon analysis of variance for crossover study designs and a P<0.05 statistical significance criterion. Results: The buffered formulation resulted in significantly lower mean blood lidocaine levels compared to unbuffered-a 63 percent (P<0.05) weight-adjusted relative decrease. The authors found no important differences in pain upon injection, onset, and duration of anesthesia. Conclusion: The buffered local anesthetic formulation showed equal effectiveness with a double-concentration unbuffered formulation while resulting in lower mean blood lidocaine levels-an important gain for the prevention of anesthetic toxicity.


Assuntos
Anestésicos Locais , Lidocaína , Tampões (Química) , Criança , Estudos Cross-Over , Método Duplo-Cego , Epinefrina , Humanos , Medição da Dor , Estudos Prospectivos
20.
Int J Mol Sci ; 22(6)2021 Mar 17.
Artigo em Inglês | MEDLINE | ID: mdl-33802882

RESUMO

The curcumin degradation represents a significant limitation for its applications. The stability of free curcumin (FC) and immobilized curcumin in complex particles (ComPs) based on different polysaccharides was studied under the action of several factors. Ultraviolet-visible (UV-VIS) and Fourier-transform infrared (FTIR) spectroscopy proved the FC photodegradation and its role as a metal chelator: 82% of FC and between 26% and 39.79% of curcumin within the ComPs degraded after exposure for 28 days to natural light. The degradation half-life (t1/2) decreases for FC when the pH increases, from 6.8 h at pH = 3 to 2.1 h at pH = 9. For curcumin extracted from ComPs, t1/2 was constant (between 10 and 13 h) and depended on the sample's composition. The total phenol (TPC) and total flavonoids (TFC) content values increased by 16% and 13%, respectively, for FC exposed to ultraviolet light at λ = 365 nm (UVA), whereas no significant change was observed for immobilized curcumin. Antioxidant activity expressed by IC50 (µmoles/mL) for FC exposed to UVA decreased by 29%, but curcumin within ComPs was not affected by the UVA. The bovine serum albumin (BSA) adsorption efficiency on the ComPs surface depends on the pH value and the cross-linking degree. ComPs have a protective role for the immobilized curcumin.


Assuntos
Curcumina/farmacologia , Polissacarídeos/química , Substâncias Protetoras/farmacologia , Adsorção , Animais , Antioxidantes/análise , Compostos de Bifenilo/química , Tampões (Química) , Bovinos , Curcumina/química , Curcumina/efeitos da radiação , Flavonoides/análise , Sequestradores de Radicais Livres/química , Concentração de Íons de Hidrogênio , Concentração Inibidora 50 , Íons , Metais/química , Fenóis/análise , Picratos/química , Soroalbumina Bovina/química , Soluções , Espectroscopia de Infravermelho com Transformada de Fourier , Raios Ultravioleta
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