Effect of milk protein glycation and gastrointestinal digestion on the growth of bifidobacteria and lactic acid bacteria

In this paper, β-lactoglobulin (β-Lg) and sodium caseinate (SC) have been glycated via Maillard reaction with galactose and lactose and, subsequently, the effect of glycoconjugates hydrolyzed under simulated gastrointestinal digestion on the growth of pure culture of Lactobacillus, Streptococcus and Bifidobacterium has been investigated. Glycopeptides were added to the growth media as the sole carbon source. None of the bacterial strains was able to grow in hydrolysates of native and control heated β-Lg and SC. However, glycopeptides were fermented, in different degree, by Lactobacillus and Bifidobacterium and hardly any effect was detected on the growth of Streptococcus. Digested β-Lg glycoconjugates showed a strain-dependent effect whereas growth profiles of bacteria when hydrolysates of SC glycoconjugates were used as substrates were very similar, regardless of the strain. A general preference towards peptides from β-Lg/SC glycated with galactose, particularly at the state of the reaction in which the highest content in the Amadori compound tagatosyl-lysine is present, was observed. SC glycoconjugates were quickly fermented by some strains, promoting their growth in a greater extent than β-Lg complexes or even glucose. Therefore, from the results obtained in this work it can be concluded that conjugation of both milk proteins with galactose and lactose via the Maillard reaction could be an efficient method to obtain novel food ingredients with a potential prebiotic character.     

Controlled release of sorbic acid from bacterial cellulose based mono and multilayer antimicrobial films

Biodegradable bacterial cellulose (BC) based films, incorporating sorbic acid (SA) as antimicrobial agent, have been obtained. Monolayer films, prepared using powdered BC (BCP) and poly(vinyl) alcohol (PVA), were coated with BC membrane to obtain multilayer films. Tests indicated that both SA and BCP concentration influenced sensitivity to water, release rate and antimicrobial ability of mono and multilayer films. Swelling degree, water vapour permeability and water solubility increased with SA content, but decreased with BCP addition. However in case of multilayer films, water solubility was negligible. Colour measurements indicated no degradation of SA during film preparation. The release of SA was faster when BCP concentration was higher but significantly slower, as a consequence of formed crystals dissolution, when antimicrobial concentration was increased. Furthermore, compared to the results for the monolayer films, an important decrease of SA release rate through the multilayer films was determined. The antimicrobial effect was tested against Escherichia coli K12-MG1655. The results obtained indicated that the new biocomposite films could be promising antimicrobial food packaging materials.     

Application of a New Engineered Strain of Yarrowia lipolytica for Effective Production of Calcium Ketoglutarate Dietary Supplements

The present study aimed to develop a technology for the production of dietary supplements based on yeast biomass and α-ketoglutaric acid (KGA), produced by a new transformant of Yarrowia lipolytica with improved KGA biosynthesis ability, as well to verify the usefulness of the obtained products for food and feed purposes. Transformants of Y. lipolytica were constructed to overexpress genes encoding glycerol kinase, methylcitrate synthase and mitochondrial organic acid transporter. The strains were compared in terms of growth ability in glycerol- and oil-based media as well as their suitability for KGA biosynthesis in mixed glycerol–oil medium. The impact of different C:N:P ratios on KGA production by selected strain was also evaluated. Application of the strain that overexpressed all three genes in the culture with a C:N:P ratio of 87:5:1 allowed us to obtain 53.1 g/L of KGA with productivity of 0.35 g/Lh and yield of 0.53 g/g. Finally, the possibility of obtaining three different products with desired nutritional and health-beneficial characteristics was demonstrated: (1) calcium α-ketoglutarate (CaKGA) with purity of 89.9% obtained by precipitation of KGA with CaCO₃, (2) yeast biomass with very good nutritional properties, (3) fixed biomass-CaKGA preparation containing 87.2 μg/g of kynurenic acid, which increases the health-promoting value of the product.     

“Dual‐Template” Synthesis of One‐Dimensional Conductive Nanoparticle Superstructures from Coordination Metal–Peptide Polymer Crystals

Bottom‐up fabrication of self‐assembled structures made of nanoparticles may lead to new materials, arrays and devices with great promise for myriad applications. Here a new class of metal–peptide scaffolds is reported: coordination polymer Ag(I)‐DLL belt‐like crystals, which enable the dual‐template synthesis of more sophisticated nanoparticle superstructures. In these biorelated scaffolds, the self‐assembly and recognition capacities of peptides and the selective reduction of Ag(I) ions to Ag are simultaneously exploited to control the growth and assembly of inorganic nanoparticles: first on their surfaces, and then inside the structures themselves. The templated internal Ag nanoparticles are well confined and closely packed, conditions that favour electrical conductivity in the superstructures. It is anticipated that these Ag(I)‐DLL belts could be applied to create long (>100 μm) conductive Ag@Ag nanoparticle superstructures and polymetallic, multifunctional Fe₃O₄@Ag nanoparticle composites that marry the magnetic and conductive properties of the two nanoparticle types.     

Third‐generation EUCLIDES concentrator results

This paper presents salient results from the third‐generation EUCLIDES linear photovoltaic concentrator, which was developed within the framework of the IDEOCONTE European project. There were two broad objectives for this project: firstly, to review and resolve the difficulties associated with previous prototypes (the Madrid prototype and the Tenerife plant), where the lack of qualification standards and quality control were identified as significant causes of failure under real‐world operation; and secondly, to optimise and commercialise the functionally effective components. During the development period, research activities focussed on cell encapsulation, the reliability of the system components, and the monitoring of field performance across three different test sites. The third‐generation EUCLIDES concentrator system has achieved an overall efficiency of 10%, which is similar to the efficiencies of previous EUCLIDES systems. The main third‐generation improvements relate to the industrialisation and improved reliability of single element system component. The expected system cost, for an annual production of 2 MW, is €3.70/Wp. However, the maximum allowable projected system cost under the Spanish feed‐in‐tariff of 2010 is €3.00/Wp. This will be very difficult to achieve with the current system efficiency. Copyright © 2011 John Wiley & Sons, Ltd.     

New liquid crystalline columnar poly(epichlorohydrin‐co‐ethylene oxide) derivatives leading to biomimetic ion channels

A new family of liquid crystalline columnar polyethers was obtained by modification of Poly(epichlorohydrin‐co‐ethylene oxide) (P(ECH‐co‐EO)) with the dendron 3,4,5‐tris[4‐(n‐dodecan‐1‐yloxy)benzyloxy]benzoate, under different conditions. The highest modification degree that we could achieve was 69%. The copolymers were fully characterized by ¹H and ¹³C nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), polarized optical microscopy (POM), and X‐ray diffraction (XRD). All copolymers exhibited liquid‐crystalline columnar behavior whose range of stability depended on the modification degree. X‐ray diffraction experiments on oriented samples showed that the dendrons are approximately perpendicular to the column axis and that their average number per unit cell ranged from 5 to 6. The formation of a stable columnar mesophase in the polyether should determine the presence of a continuous ion channel along the column axis. Therefore, these copolymers are suitable candidates for the preparation of membranes for small cation transport, in agreement with the results that we obtained by using poly(oxy‐1‐chloro methylethylene) (PECH) modified with the same dendron. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

Drebrin Regulates Acetylcholine Receptor Clustering and Organization of Microtubules at the Postsynaptic Machinery

Proper muscle function depends on the neuromuscular junctions (NMJs), which mature postnatally to complex “pretzel-like” structures, allowing for effective synaptic transmission. Postsynaptic acetylcholine receptors (AChRs) at NMJs are anchored in the actin cytoskeleton and clustered by the scaffold protein rapsyn, recruiting various actin-organizing proteins. Mechanisms driving the maturation of the postsynaptic machinery and regulating rapsyn interactions with the cytoskeleton are still poorly understood. Drebrin is an actin and microtubule cross-linker essential for the functioning of the synapses in the brain, but its role at NMJs remains elusive. We used immunohistochemistry, RNA interference, drebrin inhibitor 3,5-bis-trifluoromethyl pyrazole (BTP2) and co-immunopreciptation to explore the role of this protein at the postsynaptic machinery. We identify drebrin as a postsynaptic protein colocalizing with the AChRs both in vitro and in vivo. We also show that drebrin is enriched at synaptic podosomes. Downregulation of drebrin or blocking its interaction with actin in cultured myotubes impairs the organization of AChR clusters and the cluster-associated microtubule network. Finally, we demonstrate that drebrin interacts with rapsyn and a drebrin interactor, plus-end-tracking protein EB3. Our results reveal an interplay between drebrin and cluster-stabilizing machinery involving rapsyn, actin cytoskeleton, and microtubules.     

Magnetic Molecularly Imprinted Nano-Conjugates for Effective Extraction of Food Components—A Model Study of Tyramine Determination in Craft Beers

In this paper, magnetic molecularly imprinted nano-conjugates were synthesized to serve as selective sorbents in a model study of tyramine determination in craft beer samples. The molecularly imprinted sorbent was characterized in terms of morphology, structure, and composition. The magnetic dispersive solid phase extraction protocol was developed and combined with liquid chromatography coupled with mass spectrometry to determine tyramine. Ten samples of craft beers were analyzed using a validated method, revealing tyramine concentrations in the range between 0.303 and 126.5 mg L⁻¹. Tyramine limits of detection and quantification were 0.033 mg L⁻¹ and 0.075 mg L⁻¹, respectively. Therefore, the fabricated molecularly imprinted magnetic nano-conjugates with a fast magnetic responsivity and desirable adsorption performance could be an effective tool for monitoring tyramine levels in beverages.     

Sustained Elevated Blood Pressure Accelerates Atherosclerosis Development in a Preclinical Model of Disease

The continuous relationship between blood pressure (BP) and cardiovascular events makes the distinction between elevated BP and hypertension based on arbitrary cut-off values for BP. Even mild BP elevations manifesting as high-normal BP have been associated with cardiovascular risk. We hypothesize that persistent elevated BP increases atherosclerotic plaque development. To evaluate this causal link, we developed a new mouse model of elevated BP based on adeno-associated virus (AAV) gene transfer. We constructed AAV vectors to support transfer of the hRenin and hAngiotensinogen genes. A single injection of AAV-Ren/Ang (10¹¹ total viral particles) induced sustained systolic BP increase (130 ± 20 mmHg, vs. 110 ± 15 mmHg in controls; p = 0.05). In ApoE^−/− mice, AAV-induced mild BP elevation caused larger atherosclerotic lesions evaluated by histology (10-fold increase vs. normotensive controls). In this preclinical model, atheroma plaques development was attenuated by BP control with a calcium channel blocker, indicating that a small increase in BP within a physiological range has a substantial impact on plaque development in a preclinical model of atherosclerosis. These data support that non-optimal BP represents a risk for atherosclerosis development. Earlier intervention in elevated BP may prevent or delay morbidity and mortality associated with atherosclerosis.     

A Review of Honeybee Venom Allergens and Allergenicity

Honeybee venom is a source of proteins with allergenic properties which can result in in various symptoms, ranging from local reactions through to systematic life-threatening anaphylaxis, or even death. According to the World Allergy Organization (WAO), honeybee venom allergy is one of the most common causes of anaphylaxis. Among the proteins present in honeybee venom, 12 protein fractions were registered by the World Health Organization’s Allergen Nomenclature Sub-Committee (WHO/IUIS) as allergenic. Most of them are highly immunogenic glycoproteins that cross-react with IgE and, as a consequence, may give false positive results in allergy diagnosis. Allergenic fractions are different in terms of molecular weight and biological activity. Eight of these allergenic fractions have also been identified in honey. This explains frequent adverse reactions after consuming honey in people allergic to venom and sheds new light on the causes of allergic symptoms in some individuals after honey consumption. At the same time, it also indicates the possibility of using honey as a natural source of allergen in specific immunotherapy.