Strategy for the Enzymatic Acylation of the Apple Flavonoid Phloretin Based on Prior α-Glucosylation.

The acylation of flavonoids serves as a means to alter their physicochemical properties, enhance their stability, and improve their bioactivity. Compared with natural flavonoid glycosides, the acylation of nonglycosylated flavonoids presents greater challenges since they contain fewer reactive sites. In this work, we propose an efficient strategy to solve this problem based on a first α-glucosylation step catalyzed by a sucrose phosphorylase, followed by acylation using a lipase. The method was applied to phloretin, a bioactive dihydrochalcone mainly present in apples. Phloretin underwent initial glucosylation at the 4'-OH position, followed by subsequent (and quantitative) acylation with C8, C12, and C16 acyl chains employing an immobilized lipase from Thermomyces lanuginosus. Electrospray ionization-mass spectrometry (ESI-MS) and two-dimensional nuclear magnetic resonance spectroscopy (2D-NMR) confirmed that the acylation took place at 6-OH of glucose. The water solubility of C8 acyl glucoside closely resembled that of aglycone, but for C12 and C16 derivatives, it was approximately 3 times lower. Compared with phloretin, the radical scavenging capacity of the new derivatives slightly decreased with 2,2-diphenyl-1-picrylhydrazyl (DPPH) and was similar to 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS•+). Interestingly, C12 acyl-α-glucoside displayed an enhanced (3-fold) transdermal absorption (using pig skin biopsies) compared to phloretin and its α-glucoside.

Endothelial progenitor cells as biomarkers of diabetes-related cardiovascular complications.

Diabetes mellitus (DM) constitutes a chronic metabolic disease characterized by elevated levels of blood glucose which can also lead to the so-called diabetic vascular complications (DVCs), responsible for most of the morbidity, hospitalizations and death registered in these patients. Currently, different approaches to prevent or reduce DM and its DVCs have focused on reducing blood sugar levels, cholesterol management or even changes in lifestyle habits. However, even the strictest glycaemic control strategies are not always sufficient to prevent the development of DVCs, which reflects the need to identify reliable biomarkers capable of predicting further vascular complications in diabetic patients. Endothelial progenitor cells (EPCs), widely known for their potential applications in cell therapy due to their regenerative properties, may be used as differential markers in DVCs, considering that the number and functionality of these cells are affected under the pathological environments related to DM. Besides, drugs commonly used with DM patients may influence the level or behaviour of EPCs as a pleiotropic effect that could finally be decisive in the prognosis of the disease. In the current review, we have analysed the relationship between diabetes and DVCs, focusing on the potential use of EPCs as biomarkers of diabetes progression towards the development of major vascular complications. Moreover, the effects of different drugs on the number and function of EPCs have been also addressed.

Synthesis of b(1 ? 3) and b(1 ? 6) galactooligosaccharides from lactose and whey using a recombinant b-galactosidase from Pantoea anthophila

BACKGROUND: Milk whey, a byproduct of the dairy industry has a negative environmental impact, can be used as a raw material for added-value compounds such as galactooligosaccharides (GOS) synthesis by bgalactosidases. RESULTS: B-gal42 from Pantoea anthophila strain isolated from tejuino belonging to the glycosyl hydrolase family GH42, was overexpressed in Escherichia coli and used for GOS synthesis from lactose or milk whey. Crude cell-free enzyme extracts exhibited high stability; they were employed for GOS synthesis reactions. In reactions with 400 g/L lactose, the maximum GOS yield was 40% (w/w) measured by HPAEC-PAD, corresponding to 86% of conversion. This enzyme had a strong predilection to form GOS with b(1 ? 6) and b (1 ? 3) galactosyl linkages. Comparing GOS synthesis between milk whey and pure lactose, both of them at 300 g/L, these two substrates gave rise to a yield of 38% (60% of lactose conversion) with the same product profile determined by HPAEC-PAD. CONCLUSIONS: B-gal42 can be used on whey (a cheap lactose source) to produce added value products such as galactooligosaccharides.

Selective Synthesis of Galactooligosaccharides Containing ß(1→3) Linkages with ß-Galactosidase from Bifidobacterium bifidum (Saphera).

The transglycosylation activity of a novel commercial ß-galactosidase from Bifidobacterium bifidum (Saphera) was evaluated. The optimal conditions for the operation of this enzyme, measured with o-nitrophenyl-ß-d-galactopyranoside, were 40 °C and pH around 6.0. Although at low lactose concentrations the property of this enzyme was basically hydrolytic, an increase of lactose concentration to 400 g/L resulted in a significant formation (107.2 g/L, 27% yield) of prebiotic galactooligosaccharides (GOS). The maximum amount of GOS was obtained at a lactose conversion of approximately 90%, which contrasts with other ß-galactosidases, for which the highest GOS yield is achieved at 40-50% lactose conversion. Using high-performance anion-exchange chromatography with pulsed amperometric detection, semipreparative high-performance liquid chromatography-hydrophilic interaction liquid chromatography, mass spectrometry, and 1D and 2D NMR, we determined the structure of most of the GOS synthesized by this enzyme. The main identified products were Gal-ß(1→3)-Gal-ß(1→4)-Glc (3'-O-ß-galactosyl-lactose), Gal-ß(1→6)-Glc (allolactose), Gal-ß(1→3)-Glc (3-galactosyl-glucose), Gal-ß(1→3)-Gal (3-galactobiose), and the tetrasaccharide Gal-ß(1→3)-Gal-ß(1→3)-Gal-ß(1→4)-Glc. In general, B. bifidum ß-galactosidase showed a tendency to form ß(1→3) linkages followed by ß(1→6) and more scarcely ß(1→4).

Immobilization of the glucose isomerase from Caldicoprobacter algeriensis on Sepabeads EC-HA and its efficient application in continuous High Fructose Syrup production using packed bed reactor.

The glucose isomerase GICA from Caldicoprobacter algeriensis was immobilized by ionic adsorption on polymethacrylate carriers (Sepabeads EC-EA and EC-HA) or covalent attachment to glyoxal agarose. The Sepabeads EC-HA yielded the highest recovery of activity (89%). The optimum temperature and pH of immobilized GICA were 90 °C and 7.0, respectively, similar to the corresponding values of free enzyme. Nevertheless, the adsorbed enzyme displayed higher relative activity at acidic pH, greater thermostability, and better storage stability, compared to the free form. Moreover, the immobilized enzyme showed an excellent operational stability, in 15 successive 3 h reaction cycles at 85 °C under a batch reactor, preserving 83% of its initial activity. Interestingly, a continuous process for High Fructose Syrup (HFS) production was established with the adsorbed GICA using a packed bed reactor during eleven days at 70 °C. HPAEC-PAD analysis showed a maximum bioconversion rate of 49% after 48 h of operation.

Deciphering the molecular specificity of phenolic compounds as inhibitors or glycosyl acceptors of ß-fructofuranosidase from Xanthophyllomyces dendrorhous.

Enzymatic glycosylation of polyphenols is a tool to improve their physicochemical properties and bioavailability. On the other hand, glycosidic enzymes can be inhibited by phenolic compounds. In this work, we studied the specificity of various phenolics (hydroquinone, hydroxytyrosol, epigallocatechin gallate, catechol and p-nitrophenol) as fructosyl acceptors or inhibitors of the ß-fructofuranosidase from Xanthophyllomyces dendrorhous (pXd-INV). Only hydroquinone and hydroxytyrosol gave rise to the formation of glycosylated products. For the rest, an inhibitory effect on both the hydrolytic (H) and transglycosylation (T) activity of pXd-INV, as well as an increase in the H/T ratio, was observed. To disclose the binding mode of each compound and elucidate the molecular features determining its acceptor or inhibitor behaviour, ternary complexes of the inactive mutant pXd-INV-D80A with fructose and the different polyphenols were analyzed by X-ray crystallography. All the compounds bind by stacking against Trp105 and locate one of their phenolic hydroxyls making a polar linkage to the fructose O2 at 3.6-3.8 Å from the C2, which could enable the ulterior nucleophilic attack leading to transfructosylation. Binding of hydroquinone was further investigated by soaking in absence of fructose, showing a flexible site that likely allows productive motion of the intermediates. Therefore, the acceptor capacity of the different polyphenols seems mediated by their ability to make flexible polar links with the protein, this flexibility being essential for the transfructosylation reaction to proceed. Finally, the binding affinity of the phenolic compounds was explained based on the two sites previously reported for pXd-INV.

Effect of α-Glucosylation on the Stability, Antioxidant Properties, Toxicity, and Neuroprotective Activity of (-)-Epigallocatechin Gallate.

(-)-Epigallocatechin gallate (EGCG), the predominant catechin (≥50%) in green tea (Camellia sinensis), displays several bioactive properties but its stability and bioavailability are low. In this work, the properties of two α-glucosyl derivatives of EGCG (3'- and 7-O-α-D-glucopyranoside), obtained by enzymatic synthesis, were assessed. The α-glucosylation enhanced the pH and thermal stability of EGCG. The analysis of scavenging activity toward ABTS·+ radicals showed that the α-glucosylation at C-7 of A-ring caused a higher loss of antioxidant activity compared with the sugar conjugation at C-3' of B-ring. The 3'-glucoside also showed higher potential to alleviate intracellular reactive oxygen species (ROS) levels and to boost REDOX activity. The toxicity of EGCG and its monoglucosides was tested in human SH-S5Y5 neurons, RAW 264.7 macrophages, MRC5 fibroblasts, and HT-29 colon cancer cells. Interestingly, the 3'-O-α-D-glucoside increased the viability of neural cells in vitro (2.75-fold at 100 µM) in the presence of H2O2, whilst EGCG gave rise only to a 1.7-fold enhancement. In conclusion, the α-glucoside of EGCG at C-3' has a great potential for nutraceutical, cosmetic and biomedical applications.

Structure-Guided Immobilization of an Evolved Unspecific Peroxygenase.

Unspecific peroxygenases (UPOs) are highly promiscuous biocatalyst with self-sufficient mono(per)oxygenase activity. A laboratory-evolved UPO secreted by yeast was covalently immobilized in activated carriers through one-point attachment. In order to maintain the desired orientation without compromising the enzyme's activity, the S221C mutation was introduced at the surface of the enzyme, enabling a single disulfide bridge to be established between the support and the protein. Fluorescence confocal microscopy demonstrated the homogeneous distribution of the enzyme, regardless of the chemical nature of the carrier. This immobilized biocatalyst was characterized biochemically opening an exciting avenue for research into applied synthetic chemistry.

Optimization of Regioselective α-Glucosylation of Hesperetin Catalyzed by Cyclodextrin Glucanotransferase.

The regioselective α-glucosylation of hesperetin was achieved by a transglycosylation reaction catalyzed by cyclodextrin glucanotransferase (CGTase) from Thermoanaerobacter sp. using soluble starch as glucosyl donor. By combining mass spectrometry (ESI-TOF) and 2D-NMR analysis, the main monoglucosylated derivative was fully characterized (hesperetin 7-O-α-d-glucopyranoside). In order to increase the yield of monoglucoside, several reaction parameters were optimized: Nature and percentage of cosolvent, composition of the aqueous phase, glucosyl donor, temperature, and the concentrations of hesperetin and soluble starch. Under the optimal conditions, which included the presence of 30% of bis(2-methoxyethyl) ether as cosolvent, the maximum concentration of monoglucoside was approximately 2 mM, obtained after 24 h of reaction. To our knowledge, this is the first report of direct glucosylation of hesperetin employing free enzymes instead of whole cells.

Lipase-Catalyzed Synthesis of Fatty Acid Esters of Trisaccharides.

Carbohydrate fatty acid esters have a broad spectrum of applications in the food, cosmetic, and pharmaceutical industries. The enzyme-catalyzed acylation is significantly more selective than the chemical process and is carried out at milder conditions. Compared with mono- and disaccharides, the acylation of trisaccharides has been less studied. However, trisaccharide esters display notable bioactive properties, probably due to the higher hydrophilicity of the sugar head group. In this chapter, we describe the acylation of two trisaccharides, maltotriose and 1-kestose, catalyzed by different immobilized lipases, using vinyl esters as acyl donors. To illustrate the potential of such compounds, the antitumor activity of 6″-O-palmitoyl-maltotriose is shown.

Efficient α-Glucosylation of Epigallocatechin Gallate Catalyzed by Cyclodextrin Glucanotransferase from Thermoanaerobacter Species.

The glycosylation of plant polyphenols may modulate their solubility and bioavailability and protect these molecules from oxygen, light degradation, and during gastrointestinal transit. In this work, the synthesis of various α-glucosyl derivatives of (-)-epigallocatechin gallate, the predominant catechin in green tea, was performed in water at 50 °C by a transglycosylation reaction catalyzed by cyclodextrin glycosyltransferase from Thermoanaerobacter sp. The molecular weight of reaction products was determined by high-performance liquid chromatography coupled to mass spectrometry. Using hydrolyzed potato starch as a glucosyl donor, two main monoglucosides were obtained with conversion yields of 58 and 13%, respectively. The products were isolated and chemically characterized by combining two-dimensional nuclear magnetic resonance methods. The major derivative was epigallocatechin gallate 3'- O-α-d-glucopyranoside (1), and the minor derivative was epigallocatechin gallate 7- O-α-d-glucopyranoside (2).

Enzymatic Synthesis of a Novel Pterostilbene α-Glucoside by the Combination of Cyclodextrin Glucanotransferase and Amyloglucosidase.

The synthesis of a novel α-glucosylated derivative of pterostilbene was performed by a transglycosylation reaction using starch as glucosyl donor, catalyzed by cyclodextrin glucanotransferase (CGTase) from Thermoanaerobacter sp. The reaction was carried out in a buffer containing 20% (v/v) DMSO to enhance the solubility of pterostilbene. Due to the formation of several polyglucosylated products with CGTase, the yield of monoglucoside was increased by the treatment with a recombinant amyloglucosidase (STA1) from Saccharomyces cerevisiae (var. diastaticus). This enzyme was not able to hydrolyze the linkage between the glucose and pterostilbene. The monoglucoside was isolated and characterized by combining ESI-MS and 2D-NMR methods. Pterostilbene α-d-glucopyranoside is a novel compound. The α-glucosylation of pterostilbene enhanced its solubility in water to approximately 0.1 g/L. The α-glucosylation caused a slight loss of antioxidant activity towards ABTS˙⁺ radicals. Pterostilbene α-d-glucopyranoside was less toxic than pterostilbene for human SH-S5Y5 neurons, MRC5 fibroblasts and HT-29 colon cancer cells, and similar for RAW 264.7 macrophages.

Directed -in vitro- evolution of Precambrian and extant Rubiscos.

Rubisco is an ancient, catalytically conserved yet slow enzyme, which plays a central role in the biosphere's carbon cycle. The design of Rubiscos to increase agricultural productivity has hitherto relied on the use of in vivo selection systems, precluding the exploration of biochemical traits that are not wired to cell survival. We present a directed -in vitro- evolution platform that extracts the enzyme from its biological context to provide a new avenue for Rubisco engineering. Precambrian and extant form II Rubiscos were subjected to an ensemble of directed evolution strategies aimed at improving thermostability. The most recent ancestor of proteobacteria -dating back 2.4 billion years- was uniquely tolerant to mutagenic loading. Adaptive evolution, focused evolution and genetic drift revealed a panel of thermostable mutants, some deviating from the characteristic trade-offs in CO2-fixing speed and specificity. Our findings provide a novel approach for identifying Rubisco variants with improved catalytic evolution potential.

Evaluación epidemiológica de la exposición a ruido en trabajadores de policía local y bomberos / Epidemiological evaluation of noise exposure in workers local police and firefighters

La discusión acerca de la exclusión de determinados puestos de trabajo del ámbito de la aplicación de la Ley 31/1995, finalizó con la Sentencia del Tribunal de Justicia de las Comunidades Europeas (12//01/2006). Objetivos: Conocer el riesgo de presentar una audiometría anormal relacionada con el trabajo, en aras de poder establecer relación entre el puesto y la exposición. Material y Métodos: Estudio de casos y controles realizado durante el periodo 2006-2010 entre agentes de Policía Local, Bomberos y personal de Administración. De una población accesible de 881 trabajadores se reclutaron a 631 que cumplían criterios de inclusión. De forma aleatoria y estratificada por sexo y edad, la muestra seleccionada fue de 389 (207 casos y 182 controles). Se realizó un análisis estadístico mediante contraste de medias independientes y porcentajes y como medida de asociación se calculó la Odds Ratio (OR) para los grupos de estudio y análisis multivariante de regresión logística así como curvas ROC. Resultados: En el análisis univariante, edad, puesto de trabajo (POL) y umbrales OSHA presentaron diferencias significativas, con una OR de 2,8 (p<0.001) en el grupo de Policía Local. En el multivariante, edad, umbrales OSHA y puesto de Policía Local (OR 2,8), siguen siéndolo. El área bajo la curva ROC fue para OSHA (0,815). Conclusiones: El puesto de policía local muestra mayor riesgo de lesión neurosensorial que el de administrativo; y la evaluación epidemiológica de la salud se muestra como herramienta eficaz para la evaluación de los riesgos (AU)

The discussion about the exclusion of certain jobs in the field of application of Law 31/1995, ended with the judgment of the Court of Justice of the European Communities (12 / 01/2006). Objective: to know the risk of abnormal audiometry work-related, in order to be able to establish relationship between the position and exposure. Material and Methods: a case-control study conducted during the period 2006-2010 among local police officers, firefighters and personal Administration. An accessible population of 881 workers were recruited 631 who met inclusion criteria. Random and stratified by sex and age, the selected sample was 389 (207 cases and 182 controls). Statistical analysis was performed using contrast independent means and percentages and as a measure of association calculated the odds ratio (OR) for groups of multivariate analysis and logistic regression analysis and ROC curves. Results: in the univariate analysis, age, job (POL) and OSHA thresholds differ significantly, with an odds ratio of 2.8 (p<0.001) in the group of local police. In multivariate, age, OSHA thresholds and local police station (OR 2.8), remain so. The area under the ROC curve was to OSHA (0.815) Conclusions: the local police station shows higher risk of sensoneural injury than administrative staff, and the epidemiological assessment of health is shown as an effective tool for risk assessment (AU)

Conocer el grado de concordancia de dos métodos para detectar la colonización bacteriana de las manos del personal sanitario / No disponible

Hemos comparado los métodos "impronta de dedos" y "frotis de palma" para detectar colonización de manos por flora bacteriana. Se realizó un análisis de regresión logística para verificar la relación de los resultados del cultivo de ambos métodos de muestreo con variables explicativas probadas asociadas con la colonización bacteriana de las manos. Tras demostrar que ambos métodos no son concordantes respecto a la detección de flora colonizadora de las manos (S. epidermidis), se realizó análisis de dependencia de ambos métodos respecto a bacterias formalmente colonizadoras de manos y fosas nasales (S. aureus). Los resultados del cultivo de frotis de palma están asociados con variables explicativas probadas relacionadas con la colonización de manos como son la "ejecución del lavado higiénico de manos" y "tiempo transcurrido desde último lavado de manos" y, además, existe relación con la colonización nasal por Staphylococcus aureus. Estos resultados no se encontraron con los resultados del cultivo de impronta de dedos, por lo que el método frotis de palma evidencia más especificidad para detectar flora colonizadora en las manos

We have compared two sampling methods to isolate bacterial flora on hands, "finger imprint" and "palm smear", in order to detect colonizing bacterial flora. We carried out a logistic regression analysis of culture results from the two sampling methods with proven explanatory variables related to colonization on hand. After the evidence that both methods were not concordant in respect with the detection of hand colonizing flora (S.epidermidis), dependence analysis was carried out between both sampling methods in relation with formal colonizing bacterial flora on hands and nostril smear (S. aureus). Culture results from palm smear are associated with proven explanatory variables related to colonization on hand as 'time elapsed since last hand-washing' and 'performance of hygienic hand washing' and, in parallel, are related to Staphylococcus aureus nostril colonization. These results were not found with culture results from finger imprint. So, culture results from palm smear appear to have more specificity to detect hand colonizing bacterial flora

Micro-scale procedure for enzyme immobilization screening and operational stability assays.

OBJECTIVE: A simple and inexpensive methodology, based on the use of micro-centrifuge filter tubes, is proposed for establishing the best enzyme immobilization conditions. RESULTS: The immobilized biocatalyst is located inside the filter holder during the whole protocol, thus facilitating the incubations, filtrations and washings. This procedure minimizes the amount of enzyme and solid carrier needed, and allows exploring different immobilization parameters (pH, buffer concentration, enzyme/carrier ratio, incubation time, etc.) in a fast manner. The handling of immobilized enzymes using micro-centrifuge filter tubes can also be applied to assess the apparent activity of the biocatalysts, as well as their reuse in successive batch reaction cycles. The usefulness of the proposed methodology is shown by the determination of the optimum pH for the immobilization of an inulinase (Fructozyme L) on two anion-exchange polymethacrylate resins (Sepabeads EC-EA and Sepabeads EC-HA). CONCLUSION: The micro-scale procedure described here will help to overcome the lack of guidelines that usually govern the selection of an immobilization method, thus favouring the development of stable and robust immobilized enzymes that can withstand harsh operating conditions in industry.

Síntesis enzimática de fructooligosacáridos estimuladores de la microbiología colónica / Enzymatic synthesis of fructooligosaccharides that stimulate the gut microbiota

El control de la microflora intestinal es uno de los objetivos de los alimentos funcionales y nutracéuticos. El equilibrio simbiótico puede lograrse mediante la ingesta de microorganismos vivos (probióticos) o de los denominados prebióticos (oligosacáridos no digeribles). Los prebióticos son fermentados selectivamente por la microbiota generando cambios específicos en su composición que producen un beneficio en la salud del hospedador. Entre los prebióticos los fructooligosacáridos (FOS) constituyen uno de los grupos más importantes. Las levansacarasas (EC 2.4.1.10) son una familia de enzimas que catalizan la transferencia de un grupo fructosilo desde una sacarosa a diferentes aceptores entre ellos otra molécula de sacarosa dando lugar a FOS sobre los que puede transferir otro grupo fructosilo para llegar a formar levano un polímero con aplicaciones en alimentación y biomedicina. Si el grupo fructosilo se transfiere sobre una molécula de agua da lugar a la hidrólisis de la sacarosa. En este trabajo se caracterizó una levansacarasa de Z. mobilis y los productos de reacción con sacarosa como sustrato se analizaron por cromatografía de intercambio aniónico con detector amperométrico de pulsos (HPAEC-PAD). Con objeto de optimizar el proceso biocatalítico la enzima se inmovilizó por atrapamiento en geles de alginato cálcico y las esferas resultantes se deshidrataron para formar DALGEEs (Dry ALGinate Entrapped Enzymes). Se probaron diferentes estrategias de inmovilización para minimizar la pérdida de la enzima por los poros. El efecto de la inmovilización en el comportamiento de la levansacarasa fue analizado

The control of the intestinal flora is one of the targets of the functional foods and nutraceuticals. A symbiotic equilibrium can be achieved by the intake of live microorganisms (probiotics) or by the so-called prebiotics (non-digested oligosaccharides). Prebiotics are selectively fermented by the human microbiota allowing specific changes and conferring benefits upon host well-being and health. Among prebiotics fructooligosaccharides (FOS) constitute one of the most established groups. Levansucrases (EC 2.4.1.10) are a family of enzymes that catalyse the transfer of the fructosyl moiety from sucrose to different acceptors such as: (1) sucrose -yielding FOS that can be further fructosylated forming levan a polymer with food and biomedical applications -; (2) water resulting in sucrose hydrolysis. In this work a levansucrase from Zymomonas mobilis was characterized and the reaction products using sucrose as substrate were analysed by High-Performance Anion-Exchange Chromatography (HPAEC-PAD). The number of FOS synthesized by the soluble enzyme was significantly higher compared with previous reports. In order to optimize the biocatalytic process the enzyme was further immobilized by entrapment in calcium alginate gel and the resulting beads were dehydrated to obtain DALGEEs (Dry ALGinate Entrapped Enzymes). Different immobilization strategies were studied to minimize enzyme loss (lixiviation) throughout the pores. The effect of enzyme immobilization on levansucrase behaviour was also analysed

Estudio seroepidemiológico en trabajadores expuestos a Virus de la Hepatitis A / Seroepidemiological study in workers exposed to Hepatitis A virus

Introducción. El objetivo es realizar un estudio seroepidemiológico de los trabajadores expuestos al Virus de la Hepatitis A (VHA), para conocer la seroprevalencia de anticuerpos frente al VHA y la efectividad del programa de vacunación de Hepatitis A. Métodos. Estudio descriptivo transversal sobre la población de trabajadores expuestos al VHA en el Ayuntamiento de Córdoba, en el periodo de 2001-2012. A un total de 144 trabajadores se les solicitó una serología frente al VHA, y se realizó información y educación sanitaria sobre este riesgo biológico. La vacunación se indicó en trabajadores seronegativos. Resultados. La edad media fue de 40,2 años. El grupo laboral mayoritario fue de auxiliares de enfermería (48,6%). Se practicaron 110 serologías (76,4%), obteniendo una prevalencia de infección por VHAdel 35,5%. La primovacunación se llevó a cabo en 44 (62%), y de ellos, finalizaron completamente la misma 31 trabajadores. La efectividad del programa fue del 33,3%. Conclusiones. La seroprevalencia obtenida ha sido inferior a los estudios similares. El umbral, por debajo del cual no resulta eficiente la serología prevacunal, es para trabajadores nacidos después de 1966 (AU)

Introduction. The objective is to conduct a seroepidemiological study of workers exposed to Hepatitis A Virus ( HAV ) seroprevalence for antibodies against HAV and effectiveness of the vaccination program of hepatitis A. Methods. Cross-sectional study on the population of workers exposed to HAV in the city of Córdoba, in the period 2001-2012. A total of 144 workers were asked against HAV serology , and health information and education was performed on this biological risk. Vaccination is indicated in seronegative workers. Results. The mean age was 40.2 years. The major labor group was nurses ( 48.6 %). 110 serology (76.4% ) were performed , giving a prevalence of HAV infection of 35.5 %. The first vaccination was performed in 44 ( 62%), and they completely finished the same 31 workers . Program effectiveness was 33.3% . Conclusions. The seroprevalence obtained was lower than similar studies . The threshold below which no efficient is the pre-vaccine serology, is for workers born after 1966 (AU)

Galactooligosaccharides formation during enzymatic hydrolysis of lactose: towards a prebiotic-enriched milk.

The formation of galactooligosaccharides (GOS) in skim milk during treatment with several commercial ß-galactosidases (Bacillus circulans, Kluyveromyces lactis and Aspergillus oryzae) was analysed in detail, at 4 and 40°C. The maximum GOS concentration was obtained at a lactose conversion of approximately 40-50% with B. circulans and A. oryzae ß-galactosidases, and at 95% lactose depletion for K. lactis ß-galactosidase. Using an enzyme dosage of 0.1% (v/v), the maximum GOS concentration with K. lactis ß-galactosidase was achieved in 1 and 5h at 40 and 4 °C, respectively. With this enzyme, it was possible to obtain a treated milk with 7.0 g/L GOS - the human milk oligosaccharides (HMOs) concentration is between 5 and 15 g/L--and with a low content of residual lactose (2.1g/L, compared with 44-46 g/L in the initial milk sample). The major GOS synthesised by this enzyme were 6-galactobiose [Gal-ß(1 → 6)-Gal], allolactose [Gal-ß(1 → 6)-Glc] and 6'-O-ß-galactosyl-lactose [Gal-ß(1 → 6)-Gal-ß(1 → 4)-Glc].

Analysis of fermentation selectivity of purified galacto-oligosaccharides by in vitro human faecal fermentation.

The in vitro fermentation of several purified galacto-oligosaccharides (GOS), specifically the trisaccharides 4'-galactosyl-lactose and 6'-galactosyl-lactose and a mixture of the disaccharides 6-galactobiose and allolactose, was carried out. The bifidogenic effect of GOS at 1% (w/v) was studied in a pH-controlled batch culture fermentation system inoculated with healthy adult human faeces. Results were compared with those obtained with a commercial GOS mixture (Bimuno-GOS). Changes in bacterial populations measured through fluorescence in situ hybridization and short-chain fatty acid (SCFA) production were determined. Bifidobacteria increased after 10-h fermentation for all the GOS substrates, but the changes were only statistically significant (P<0.05) for the mixture of disaccharides and Bimuno-GOS. Acetic acid, whose formation is consistent with bifidobacteria metabolism, was the major SCFA synthesized. The acetate concentration at 10 h was similar with all the substrates (45-50 mM) and significantly higher than the observed for formic, propionic and butyric acids. All the purified GOS could be considered bifidogenic under the assayed conditions, displaying a selectivity index in the range 2.1-3.0, which was slightly lower than the determined for the commercial mixture Bimuno-GOS.