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1.
Food Funct ; 11(7): 5875-5886, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32578654

RESUMO

Galactooligosaccharides (GOS) are useful dietary ingredients recognized worldwide as prebiotics. In the present study, we evaluated the ß-galactosidase (ß-gal) activity of a panel of lactic acid bacteria (LAB) in order to select strains for the synthesis of oligosaccharides from lactose (GOS) and lactulose (OsLu) with a potential prebiotic effect. Fifteen strains out of 20 were able to grow on lactose and showed ß-gal activities between 0.03 and 2.06 U mg-1, whereas eleven were able to synthesize GOS. Lactobacillus delbrueckii subsp. bulgaricus CRL450, the strain with the highest ß-gal activity, synthesized a maximum of 41.3% GOS and 21.0% OsLu from lactose and lactulose, respectively, with ß-(1 → 6) and secondary ß-(1 → 3) linkages. When these compounds were tested without purifying, as carbon sources for the development of recognized probiotics and the producer strain, high growth was observed compared to non-prebiotic sugars like glucose and lactose. When the purified oligosaccharides were tested, the bacterial growth decreased, but the microorganisms displayed metabolic activity evidenced by the consumption of carbohydrates and the production of lactic acid. Additionally, the purified oligosaccharides demonstrated a bifidogenic effect. The obtained results support the potential of L. delbrueckii subsp. bulgaricus CRL450 for the production of the prebiotics GOS and OsLu and encourage the optimization of their synthesis for the design of new functional food ingredients.

2.
Sci Rep ; 10(1): 960, 2020 01 22.
Artigo em Inglês | MEDLINE | ID: mdl-31969624

RESUMO

Vancomycin, a branched tricyclic glycosylated peptide antibiotic, is a last-line defence against serious infections caused by staphylococci, enterococci and other Gram-positive bacteria. Orally-administered vancomycin is the drug of choice to treat pseudomembranous enterocolitis in the gastrointestinal tract. However, the risk of vancomycin-resistant enterococcal infection or colonization is significantly associated with oral vancomycin. Using the powerful matrix-free assay of co-sedimentation analytical ultracentrifugation, reinforced by dynamic light scattering and environmental scanning electron microscopy, and with porcine mucin as the model mucin system, this is the first study to demonstrate strong interactions between vancomycin and gastric and intestinal mucins, resulting in very large aggregates and depletion of macromolecular mucin and occurring at concentrations relevant to oral dosing. In the case of another mucin which has a much lower degree of glycosylation (~60%) - bovine submaxillary mucin - a weaker but still demonstrable interaction is observed. Our demonstration - for the first time - of complexation/depletion interactions for model mucin systems with vancomycin provides the basis for further study on the implications of complexation on glycopeptide transit in humans, antibiotic bioavailability for target inhibition, in situ generation of resistance and future development strategies for absorption of the antibiotic across the mucus barrier.

3.
Food Funct ; 10(12): 7793-7805, 2019 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-31781703

RESUMO

Anti-inflammatory properties of artichoke pectin and modified fractions (arabinose- and galactose-free) used at two doses (40 and 80 mg kg-1) in mice with colitis induced by dextran sulfate sodium have been investigated. Expression of pro-inflammatory markers TNF-α and ICAM-I decreased in groups of mice treated with original and arabinose-free artichoke pectin while IL-1ß and IL-6 liberation was reduced only in mice groups treated with original artichoke pectin. A decrease in iNOS and TLR-4 expression was observed for most treatments. Intestinal barrier gene expression was also determined. MUC-1 and Occludin increased in groups treated with original artichoke pectin while MUC-3 expression also increased in arabinose-free pectin treatment. Galactose elimination led to a loss of pectin bioactivity. Characteristic expression profiles were established for each treatment through artificial neural networks showing high accuracy rates (≥90%). These results highlight the potential amelioration of inflammatory bowel disease on mice model colitis through artichoke pectin administration.


Assuntos
Anti-Inflamatórios/administração & dosagem , Colite/tratamento farmacológico , Cynara scolymus/química , Pectinas/administração & dosagem , Extratos Vegetais/administração & dosagem , Animais , Colite/induzido quimicamente , Colite/genética , Colite/imunologia , Sulfato de Dextrana/efeitos adversos , Modelos Animais de Doenças , Humanos , Interleucina-1beta/genética , Interleucina-1beta/imunologia , Interleucina-6/genética , Interleucina-6/imunologia , Intestinos/efeitos dos fármacos , Intestinos/imunologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Receptor 4 Toll-Like/genética , Receptor 4 Toll-Like/imunologia
4.
Nanoscale ; 11(41): 19462-19467, 2019 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-31528938

RESUMO

Conductance measurements in single-molecule junctions (SMJs) are on many occasions accompanied by inelastic spectroscopy and shot-noise measurements in order to obtain information about different vibration modes (or vibrons) and channels involved in the transport respectively. We have extended the single-molecule shot-noise measurements, which were previously performed at low bias, to high bias and we have studied the effects of these vibrons on the noise for a Deuterium (D2) molecule between Pt leads. We report here two important findings from these measurements. First, we find in our noise measurements that at the vibron energies of the molecule, a two-level fluctuation (TLF) is excited in the junction. Second, we show that in the presence of this TLF, a form of enhanced noise spectroscopy can be performed to detect inelastic electron-vibron interactions, by studying the third derivative of the noise (d3SI/dV3). This is possible because TLFs are insensitive to elastic scattering of electrons from defects, which nevertheless leave their signature in the usual inelastic electron tunnelling spectroscopy (IETS) measurements.

5.
J Agric Food Chem ; 67(26): 7435-7447, 2019 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-31244205

RESUMO

Pectic oligosaccharides (POS) from citrus and apple pectin hydrolysis using ViscozymeL and Glucanex200G have been obtained. According to the results, maximum POS formation was achieved from citrus pectin after 30 min of hydrolysis with ViscozymeL, with a yield of 652 mg g-1 and average molecular mass ( Mw) of 0.8-2.5 kDa, while with Glucanex200G, the yield was 518 mg g-1 and Mw was 0.8-7.1 kDa. Digalacturonic and trigalacturonic acids were identified among other low Mw compounds as di- and tri-POS. In addition, differences in GC-MS spectra of all oligosaccharides found in the hydrolysates were studied by employing random forests and other algorithms to identify structural differences between the obtained POS, and high prediction rates were shown for new samples. Chemical structures were proposed for some influential m/ z ions, and 12 association rules that explain differences according to pectin and enzyme origin were built. This information could be used to establish structure-function relationships of POS.


Assuntos
Citrus/química , Malus/química , Complexos Multienzimáticos/química , Oligossacarídeos/química , Pectinas/química , Extratos Vegetais/química , Biocatálise , Cromatografia Gasosa-Espectrometria de Massas , Hidrólise , Peso Molecular
6.
Carbohydr Polym ; 205: 513-523, 2019 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-30446135

RESUMO

Novel artichoke pectic-oligosaccharides (POS) mixtures have been obtained by enzymatic hydrolysis using four commercial enzyme preparations: Glucanex®200G, Pentopan®Mono-BG, Pectinex®Ultra-Olio and Cellulase from Aspergillus niger. Analysis by HPAEC-PAD showed that Cellulase from A. niger produced the greatest amount of POS (310.6 mg g-1 pectin), while the lowest amount was produced by Pentopan®Mono-BG (45.7 mg g-1 pectin). To determine structural differences depending on the origin of the enzyme, GC-MS spectra of di- and trisaccharides have been studied employing three machine learning algorithms: multilayer perceptron, random forest and boosted logistic regression. Machine learning models allowed characteristic m/z ions patterns to be established for each enzyme based on their GC-MS spectra with high prediction rates (above 95% on the test set). Possible chemical structures were given for some m/z ions having a decisive influence on these classifications. Finally, it was observed that several ions could be formed from specific POS structures.

7.
Food Microbiol ; 77: 93-105, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30297061

RESUMO

The potential of probiotic bacteria to produce prebiotic oligosaccharides by transgalactosylation has been minimally studied. In this work, we screened the ß-galactosidase (ß-gal) activity of dairy propionibacteria (PAB) isolated from Argentinean foods to select strains for the synthesis of oligosaccharides from lactose (GOS) and lactulose (OsLu). PAB, when grown in a medium with lactose as a carbon source, were disrupted, and the cell-free extracts were assayed for ß-gal activity. Nine strains grew on lactose and showed ß-gal activities from 0.27 to 2.60 U mL-1. Propionibacterium acidipropionici LET 120, the strain with the highest activity, was able to synthesize, using 30% lactose and lactulose at pH 6.5 and 45 °C, 26.8% of LET 120-GOS and 26.1% of LET 120-OsLu after 24 h. When they were tested as carbon sources for growth, P. acidipropionici LET 120 attained higher biomasses, µmax and ß-gal activities at the expense of Aspergillus oryzae-OsLu, Vivinal®-GOS and lactulose compared to lactose or glucose. In addition, LET 120-GOS and LET 120-OsLu synthesized by PAB were prebiotic for some probiotic strains. For the first time, our results show the production of GOS and OsLu by dairy PAB, and these results encourage further studies on the optimization of the synthesis and structure characterization of the obtained oligosaccharides.


Assuntos
Lactose/metabolismo , Lactulose/metabolismo , Oligossacarídeos/biossíntese , Prebióticos , Propionibacterium/metabolismo , Animais , Aspergillus oryzae , Queijo/microbiologia , Meios de Cultura/química , Leite/microbiologia , Oligossacarídeos/química , Probióticos , Propionibacterium/crescimento & desenvolvimento , Propionibacterium/isolamento & purificação , Fatores de Tempo , beta-Galactosidase/metabolismo
8.
Carbohydr Polym ; 190: 43-49, 2018 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-29628258

RESUMO

The aim of this study was to optimise pectin extraction from artichoke by-products with Celluclast®1.5L using an experimental design analysed by response-surface methodology (RSM). The variables optimised were artichoke by-product powder concentration (2-7%, X1), enzyme dose (2.2-13.3 U g-1, X2) and extraction time (6-24 h, X3). The variables studied were galacturonic acid (GalA) (R2 93.9) and pectic neutral sugars (R2 92.8) content and pectin yield (R2 88.6). In the optimum extraction conditions (X1 = 6.5%; X2 = 10.1 U g-1; X3 = 27.2 h), pectin yield was 176 mgg-1 dry matter (DM). Considering 27.2 h of treatment as the +α value given by the design, the extraction time was increased up to 48 h obtaining a yield of 221 mg g-1 DM. The enzymatic method optimised allows obtaining artichoke pectin with good yield, high GalA (720 mg g-1 DM) and arabinose (127.6mgg-1 DM) contents and degree of methylation of 19.5%.


Assuntos
Fracionamento Químico/métodos , Enzimas/metabolismo , Resíduos Industriais , Pectinas/isolamento & purificação , Pectinas/química
9.
Nano Lett ; 18(4): 2505-2510, 2018 04 11.
Artigo em Inglês | MEDLINE | ID: mdl-29513997

RESUMO

The investigation of the transport properties of single molecules by flowing tunneling currents across extremely narrow gaps is relevant for challenges as diverse as the development of molecular electronics and sequencing of DNA. The achievement of well-defined electrode architectures remains a technical challenge, especially due to the necessity of high precision fabrication processes and the chemical instability of most bulk metals. Here, we illustrate a continuously adjustable tunneling junction between the edges of two twisted graphene sheets. The unique property of the graphene electrodes is that the sheets are rigidly supported all the way to the atomic edge. By analyzing the tunneling current characteristics, we also demonstrate that the spacing across the gap junction can be controllably adjusted. Finally, we demonstrate the transition from the tunneling regime to contact and the formation of an atomic-sized junction between the two edges of graphene.

10.
Rev Sci Instrum ; 88(9): 093903, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28964189

RESUMO

Shot noise measurements on atomic and molecular junctions provide rich information about the quantum transport properties of the junctions and on the inelastic scattering events taking place in the process. Dissipation at the nanoscale, a problem of central interest in nano-electronics, can be studied in its most explicit and simplified form. Here, we describe a measurement technique that permits extending previous noise measurements to a much higher frequency range, and to much higher bias voltage range, while maintaining a high accuracy in noise and conductance. We also demonstrate the advantages of having access to the spectral information for diagnostics.

11.
J Sci Food Agric ; 97(15): 5074-5082, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-28417455

RESUMO

BACKGROUND: One of the most promising uses of whey permeate (WP) is the synthesis of prebiotic oligosaccharides. Herein, commercial WP was submitted to chemical isomerization catalysed by sodium borate at an alkaline pH and subsequent purification using anion-exchange resins to remove boron. Subsequently, purified mixtures were used to synthesize prebiotic oligosaccharides using ß-galactosidase from Bacillus circulans. RESULTS: Isomerization of concentrated WP (200 g L-1 lactose) gave rise to levels of lactulose up to 155.5 g L-1 after 30 min of reaction (molar ratio of boron/lactose, 1/1; pH 12; 70 °C). Boron was removed from the isomerized WP (IWP) using the combination of a strong acid (IR-120, H+ ) and a weak base (IRA-743) anion-exchange resins, reducing its level to <1 ppm, without loss of lactulose. During the transglycosylation reaction of purified IWP (lactose/lactulose ratio, 1/2.4) maximum content of prebiotic compounds was achieved, i.e. 690 g kg-1 WP after 3 h of reaction. CONCLUSION: This study shows that combined chemical-enzymatic reactions together with the purification of IWP results in an efficient synthesis of prebiotic oligosaccharides. © 2017 Society of Chemical Industry.


Assuntos
Bacillus/enzimologia , Proteínas de Bactérias/química , Lactulose/química , Oligossacarídeos/química , Prebióticos/análise , Soro do Leite/química , beta-Galactosidase/química , Biocatálise , Isomerismo , Oligossacarídeos/isolamento & purificação
12.
Food Chem ; 194: 6-11, 2016 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-26471520

RESUMO

Since breastfeeding is not always possible, infant formulas (IFs) are supplemented with prebiotic oligosaccharides, such as galactooligosaccharides (GOS) and/or fructooligosaccharides (FOS) to exert similar effects to those of the breast milk. Nowadays, a great number of infant formulas enriched with prebiotics are disposal in the market, however there are scarce data about their composition. In this study, the combined use of two chromatographic methods (GC-FID and HPLC-RID) for the quantification of carbohydrates present in commercial infant formulas have been used. According to the results obtained by GC-FID for products containing prebiotics, the content of FOS, GOS and GOS/FOS was in the ranges of 1.6-5.0, 1.7-3.2, and 0.08-0.25/2.3-3.8g/100g of product, respectively. HPLC-RID analysis allowed quantification of maltodextrins with degree of polymerization (DP) up to 19. The methodology proposed here may be used for routine quality control of infant formula and other food ingredients containing prebiotics.


Assuntos
Fórmulas Infantis/química , Prebióticos/análise , Animais , Feminino , Humanos , Lactente , Masculino
13.
Beilstein J Nanotechnol ; 6: 2338-44, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26734525

RESUMO

This experimental work aims at probing current-induced forces at the atomic scale. Specifically it addresses predictions in recent work regarding the appearance of run-away modes as a result of a combined effect of the non-conservative wind force and a 'Berry force'. The systems we consider here are atomic chains of Au and Pt atoms, for which we investigate the distribution of break down voltage values. We observe two distinct modes of breaking for Au atomic chains. The breaking at high voltage appears to behave as expected for regular break down by thermal excitation due to Joule heating. However, there is a low-voltage breaking mode that has characteristics expected for the mechanism of current-induced forces. Although a full comparison would require more detailed information on the individual atomic configurations, the systems we consider are very similar to those considered in recent model calculations and the comparison between experiment and theory is very encouraging for the interpretation we propose.

14.
Nanoscale Res Lett ; 8(1): 257, 2013 May 29.
Artigo em Inglês | MEDLINE | ID: mdl-23718316

RESUMO

: We have studied experimentally jump-to-contact (JC) and jump-out-of-contact (JOC) phenomena in gold electrodes. JC can be observed at first contact when two metals approach each other, while JOC occurs in the last contact before breaking. When the indentation depth between the electrodes is limited to a certain value of conductance, a highly reproducible behaviour in the evolution of the conductance can be obtained for hundreds of cycles of formation and rupture. Molecular dynamics simulations of this process show how the two metallic electrodes are shaped into tips of a well-defined crystallographic structure formed through a mechanical annealing mechanism. We report a detailed analysis of the atomic configurations obtained before contact and rupture of these stable structures and obtained their conductance using first-principles quantum transport calculations. These results help us understand the values of conductance obtained experimentally in the JC and JOC phenomena and improve our understanding of atomic-sized contacts and the evolution of their structural characteristics.

15.
Cir. Esp. (Ed. impr.) ; 78(4): 246-250, oct. 2005. ilus, tab
Artigo em Espanhol | IBECS | ID: ibc-040899

RESUMO

Introducción. El objetivo de este estudio es revisar nuestra experiencia en el diagnóstico y tratamiento de los aneurismas de las arterias viscerales. Material y método. Estudio retrospectivo mediante revisión de historias clínicas de los pacientes diagnosticados de aneurismas viscerales desde 1984 hasta 2003. Se examinan su diagnóstico, su tratamiento y su seguimiento. Resultados. Se diagnosticaron 32 aneurismas en 27 pacientes (17 varones y 10 mujeres). Doce aneurismas de arteria esplénica (AE), 6 de hepática (AH), 5 de tronco celíaco (TC), 3 de gastroduodenal, 1 de yeyunal, 1 pancreatoduodenal, 1 aneurisma de mesentérica superior (MS) ­asociado a un aneurisma de esplénica, renal y de tronco celíaco­, 1 de mesentérica inferior (MI), 1 de arteria cística y 1 caso de microaneurismas parenquimatosos hepatorrenales. Ocho aneurismas no fueron tratados. Tres fueron embolizados. Se excluyó un aneurisma con una endoprótesis cubierta. Veinte aneurismas fueron tratados quirúrgicamente. Se practicó ligadura o exclusión en 11 casos, lobectomía hepática en 1, resecciones con revascularización en 4 casos, endoaneurismorrafias en 3 y sutura simple en 1 seudoaneurisma de AH. Conclusiones. Las actuales técnicas de diagnóstico favorecen un tratamiento precoz y en ocasiones mínimamente invasivo. La afección aneurismática esplácnica es de difícil sospecha diagnóstica y requiere técnicas de reparación muy variadas (AU)


Introduction. The aim of this study was to review our experience in the diagnosis and treatment of visceral artery aneurysms. Material and method. We performed a retrospective study through review of the medical records of patients diagnosed with visceral aneurysms from 1984 to 2003. Diagnosis, treatment and follow-up were analyzed. Results. Thirty-two aneurysms were diagnosed in 27 patients (17 men and 10 women). There were 12 aneurysms of the splanchnic artery, six of the hepatic artery, five of the celiac trunk, three gastroduodenal, one jejunal, one pancreaticoduodenal, one superior mesenteric -associated with a splanchnic, renal and celiac trunk aneurysm-, one inferior mesenteric, one cystic artery and one case of parenchymatous hepatorenal microaneurysms. Eight aneurysms were not treated. Three underwent embolization. One aneurysm was excluded with a covered endoprosthesis. Twenty aneurysms were treated surgically. Ligature or exclusion was performed in 11 patients, hepatic lobectomy in one patient, resection with revascularization in four patients, endoaneurysmorrhaphy in three patients and simple suture was performed in one hepatic artery pseudoaneurysm. Conclusions. Current diagnostic techniques favor early and sometimes minimally invasive treatment. Splanchnic aneurysms are more difficult to diagnose and require highly varied repair techniques (AU)


Assuntos
Masculino , Feminino , Adulto , Pessoa de Meia-Idade , Idoso , Humanos , Aneurisma/diagnóstico , Aneurisma/terapia , Artérias Mesentéricas/cirurgia , Artéria Hepática/patologia , Artéria Hepática/cirurgia , Artérias Mesentéricas , Artérias Mesentéricas/patologia , Estudos Retrospectivos , Falso Aneurisma/complicações , Falso Aneurisma/diagnóstico , Aneurisma/etiologia , Tomografia Computadorizada de Emissão/métodos
16.
Cir Esp ; 78(4): 246-50, 2005 Oct.
Artigo em Espanhol | MEDLINE | ID: mdl-16420833

RESUMO

INTRODUCTION: The aim of this study was to review our experience in the diagnosis and treatment of visceral artery aneurysms. MATERIAL AND METHOD: We performed a retrospective study through review of the medical records of patients diagnosed with visceral aneurysms from 1984 to 2003. Diagnosis, treatment and follow-up were analyzed. RESULTS: Thirty-two aneurysms were diagnosed in 27 patients (17 men and 10 women). There were 12 aneurysms of the splanchnic artery, six of the hepatic artery, five of the celiac trunk, three gastroduodenal, one jejunal, one pancreaticoduodenal, one superior mesenteric--associated with a splanchnic, renal and celiac trunk aneurysm--, one inferior mesenteric, one cystic artery and one case of parenchymatous hepatorenal microaneurysms. Eight aneurysms were not treated. Three underwent embolization. One aneurysm was excluded with a covered endoprosthesis. Twenty aneurysms were treated surgically. Ligature or exclusion was performed in 11 patients, hepatic lobectomy in one patient, resection with revascularization in four patients, endoaneurysmorrhaphy in three patients and simple suture was performed in one hepatic artery pseudoaneurysm. CONCLUSIONS: Current diagnostic techniques favor early and sometimes minimally invasive treatment. Splanchnic aneurysms are more difficult to diagnose and require highly varied repair techniques.


Assuntos
Aneurisma , Artéria Celíaca , Artérias Mesentéricas , Vísceras/irrigação sanguínea , Adulto , Idoso , Idoso de 80 Anos ou mais , Aneurisma/diagnóstico , Aneurisma/cirurgia , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos
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