Validation of differential pulse polarographic method of ascorbic acid assay in food – Comparison with the chromatographic reference method

The objective of the study was to demonstrate the applicability of differential pulse polarography (DPP) technique of the ascorbic acid (AA) assay for the analysis of food samples with various matrices. The following validation parameters were determined: selectivity, linearity, precision, accuracy, limit of detection, and limit of quantification. The limits of detection and quantification were 0.17 and 0.5 mg ascorbic acid per 100 g food, respectively. The average recovery of added ascorbic acid from all matrices was 96.3–103.6%. The values of the coefficient of variation calculated on the basis of AA contents for food matrices were in the range 2–9.26% and Horrat values were 0.37–1.10. Ascorbic acid values of the samples obtained from the polarographic method were compared with those obtained from high-performance liquid chromatography with diode-array detection (HPLC-DAD) used as the reference method. The analytical parameters determined showed that the polarographic method was equivalent to the chromatographic method. Validation of the polarographic method of ascorbic acid assay indicates that it can be applied for the analysis of ascorbic acid concentration in food products that do not contain isoascorbic acid. This means that the method can be recommended for routine determinations

Use of sweeteners in osmotic pretreatment before freeze-drying of pear and pineapple

The aim of the study was to analyse the influence of the type of osmotic substance (sucrose, glucose, xylitol, trehalose, and sorbitol) on the physicochemical properties of freeze-dried fruit (pear and pineapple). Controlling the functional properties of freeze-dried fruit after osmotic dehydration with aqueous solutions at water activity of a w=0.90 is presented. Decrease in the water adsorption index (WAI) was recorded for all dehydrated samples. The largest decrease (for pears and pineapples by 25 and 65%, respectively) was observed in osmoactive solutions containing trehalose. Considerable increase in the FAI was recorded in samples of dehydrated pineapple. In osmoactive trehalose solutions that increase hardly reached 46%, whereas in sorbitol and xylitol its value elevated to 39% and 13%, respectively. Regardless of the osmoactive sweetener applied prior to freeze-drying, an increase in specific surface area (SBET) of dried materials was observed. For dehydrated pears, SBET ranged from 96 to 697 m2 g−1, and for pineapple, from 115 to 938 m2 g−1. Osmotic dehydration before lyophilisation of fruit samples weakened rehydration relative to the control. The dehydration carried out with osmoactive sweeteners, that is, sorbitol, xylitol, and trehalose, allows obtaining a product with good functional properties that can be successfully used for supplementation of dietary products, in particular for diabetics

Proizvodnja i kakvoća kokoši nesilica hranjenih obrocima s niskim fosforom na osnovi žitarica s dodatkom fitaze

The purpose of the present study was to evaluate the response of laying hens to the low-phosphorus diets based on different kinds of cereal grains and supplemented with microbial phytase. Laying performance, feed intake, egg shell quality as well as bone strength parameters and Ca, P, Mg and Zn contents in the bones were involved as experimental parameters. At the age of 17 weeks, 288 Lohmann Brown pullets were assigned to the six dietary treatments, each treatment consisting of 12 cages with 4 birds per one. Until the beginning of the laying period the pullets were fed a standard diet containing 145 g of crude protein and 11.3 MJ ME, 4 g non-phytate P and 10.6 g of Ca per kg feed. The experimental diets provided from the first day of laying were based on maize (diets I, II, III) or on a combination of maize, barley and wheat (diets IV, V, VI) and contained about 165 g CP and 11.2 MJ ME/kg. In diets I, III or IV and VI the level of non-phytate phosphorus was decreased to 1.41 g/kg while in control diets (III or V) the amount of non-phytate P was 3.0 g/kg. In low-P diets III and VI microbial 6-phytase was included at the level of 450 FTU/kg diet. The phosphorus level in diets did not affect the laying rate during the experimental period of 53 weeks. The higher P-level in feed enhanced egg shell strength only (P<0.01). Supplementation of low-P-diets with phytase did not affect the performance of hens, such as feed intake and egg quality, however it improved the egg shell strength as compared to low-P unsupplemented groups. Regarding strength and elasticity of the tibia, the P-level and phytase supplement were without visible effects. The best parameters that characterize the bone quality were obtained by addition of 3 g of non-phytate P level per kg of diets.Svrha ovog istraživanja bila je ocijeniti odgovor kokoši nesilica na obroke s niskim fosforom na bazi raznih vrsta žitarica s dodatkom mikrobijelne fitaze. Nesenje, unos hrane, kakvoća ljuske jaja kao i parametri čvrstoće kosti i sadržaj Ca, P, Mg i Zn u kostima bili su obuhvaćeni kao pokusni parametri. U dobi od 17 tjedana 288 pilenki Lohmann Brown izabrano je za šest hranidbenih tretmana, a svaki tretman sastojao se od 12 kaveza po 4 pilenke. Do početka nesenja pilenke su hranjene standardnim obrocima koji su sadržavali 145 g sirovih bje¬lančevina i 11.3 MJ ME, 4 g nefitinskog P i 10.6 g Ca po kilogramu hrane. Pokusni obroci su se prvog dana nesenja temeljili na kukuruzu (obro¬ci I, II, III) ili na kombinaciji kukuruza, ječma i pšenice (obroci IV, V, VI) i sadržavali su oko 165 g CP i 11.2 Mj ME/kg. U obrocima I, III ili IV i VI razina nefitinskog fosfora smanjena je na 1.41 g/kg dok je u kontrolnim obrocima (III ili V/) količina nefitinskog P bila 3.0 g/kg. U obrocima s niskim P (III i VI) uključena je mikrobijelna 6-fitaza na razini od 450 FTU/ kg obroka. Razina fosfora u obrocima nije djelovala na postotak nesivosti u pokusu od 54 tjedna. Više razine P u hrani povećale su samo čvrstoću ljuske jajeta. (P < 0,01). Dodavanje fitaze u obroke s niskim P nije dje¬lovalo na unos hrane i kakvoću jaja, međutim poboljšalo je čvrstoću ljuske jajeta u usporedbi sa skupinama s niskim P bez dodataka. Što se tiče čvrstoće i elastičnosti goljenice, razina P i dodavanje fitaze nije imalo vidljivih učinaka. Najbolji parametri koji karakteriziraju kakvoću kosti dobiveni su dodavanjem 3 g nefitinskog P na kg obroka

Leptin-induced endothelium-dependent vasorelaxation of peripheral arteries in lean and obese rats: role of nitric oxide and hydrogen sulfide.

Published onlineJournal ArticleResearch Support, Non-U.S. Gov'tAdipose tissue hormone leptin induces endothelium-dependent vasorelaxation mediated by nitric oxide (NO) and endothelium-derived hyperpolarizing factors (EDHF). Previously it has been demonstrated that in short-term obesity the NO-dependent and the EDHF-dependent components of vascular effect of leptin are impaired and up-regulated, respectively. Herein we examined the mechanism of the EDHF-dependent vasodilatory effect of leptin and tested the hypothesis that alterations of acute vascular effects of leptin in obesity are accounted for by chronic hyperleptinemia. The study was performed in 5 groups of rats: (1) control, (2) treated with exogenous leptin for 1 week to induce hyperleptinemia, (3) obese, fed highly-palatable diet for 4 weeks, (4) obese treated with pegylated superactive rat leptin receptor antagonist (PEG-SRLA) for 1 week, (5) fed standard chow and treated with PEG-SRLA. Acute effect of leptin on isometric tension of mesenteric artery segments was measured ex vivo. Leptin relaxed phenylephrine-preconstricted vascular segments in NO- and EDHF-dependent manner. The NO-dependent component was impaired and the EDHF-dependent component was increased in the leptin-treated and obese groups and in the latter group both these effects were abolished by PEG-SRLA. The EDHF-dependent vasodilatory effect of leptin was blocked by either the inhibitor of cystathionine γ-lyase, propargylglycine, or a hydrogen sulfide (H2S) scavenger, bismuth (III) subsalicylate. The results indicate that NO deficiency is compensated by the up-regulation of EDHF in obese rats and both effects are accounted for by chronic hyperleptinemia. The EDHF-dependent component of leptin-induced vasorelaxation is mediated, at least partially, by H2S.The study was supported by the EU Project “The equipment of innovative laboratories doing research on new medicines used in the therapy of civilization and neoplastic diseases” within the Operational Program Development of Eastern Poland 2007 - 2013, Priority Axis I Modern Economy, Operations I.3 Innovation Promotion. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

KnotProt: a database of proteins with knots and slipknots

The protein topology database KnotProt, http://knotprot.cent.uw.edu.pl/, collects information about protein structures with open polypeptide chains forming knots or slipknots. The knotting complexity of the cataloged proteins is presented in the form of a matrix diagram that shows users the knot type of the entire polypeptide chain and of each of its subchains. The pattern visible in the matrix gives the knotting fingerprint of a given protein and permits users to determine, for example, the minimal length of the knotted regions (knot's core size) or the depth of a knot, i.e. how many amino acids can be removed from either end of the cataloged protein structure before converting it from a knot to a different type of knot. In addition, the database presents extensive information about the biological functions, families and fold types of proteins with non-trivial knotting. As an additional feature, the KnotProt database enables users to submit protein or polymer chains and generate their knotting fingerprint

Clinical and neuropathological picture of familial encephalopathy with bifunctional protein deficiency

Peroxisomal diseases are a heterogeneous group of genetic metabolic disorders which are caused by incorrect biogenesis of peroxisomes or a defect in activity of particular enzymes located in those organelles. D-bifunctional protein (D-BP) deficiency belongs to the second group of peroxisomal diseases characterised by dysfunction of a single peroxisomal enzyme. Bifunctional protein is a catalyst in the second and third stage of the \beta-oxidation of fatty acids. Gene locus of bifunctional protein deficiency comprises chromosomes 5q2 and 3p23-p22. The authors present two siblings with progressing family encephalopathy. In the younger brother the diagnosis of a bifunctional protein deficiency was made. The girl died before a diagnosis was made; however, due to the presence of a very similar clinical condition a suspicion arises that the girl had a peroxisomal disease. In the siblings were ascertained characteristic dysmorphic features, delayed psychomotor development, polymorphic epileptic seizures and generalized muscular hypotonia with areflexia. The neuropathological findings were consistent in general with MRI findings showing features of hypomyelination. Also neuron heterotopias that were found in autopsy are a form of pathology typical for D-BP

Dopant clustering and vacancy ordering in neodymium doped ceria

Lanthanide doped cerias, show fast oxide ion conduction and have applications as electrolytes in intermediate temperature solid oxide fuel cells. Here, we examine the long- and short-range structures of Ce1−xNdxO2−x/2 (0.05 ≤ x ≤ 0.30, NDC) using reverse Monte Carlo modelling of total neutron scattering data, supported by measurements of electrical behaviour using a.c. impedance spectroscopy. Three distinct features are evident in the local structure of NDC, viz.: clustering of Nd3+ cations, preferred Nd3+-oxide ion vacancy association and oxide ion vacancy clustering with preferential alignment in the 〈100〉 direction. Interestingly, the presence of preferential dopant cation-oxide ion vacancy association is also observed at 600 °C, although diminished compared to the level at room temperature. This suggests a continued contribution of defect association enthalpy to activation energy at elevated temperatures and is reflected in similar compositional variation of high- and low-temperature activation energies

Deuteron-deuteron collision at 160 MeV

The experiment was carried out using BINA detector at KVI in Groningen. For the first time an extensive data analysis of the data collected in back part of the detector is presented, where a clusterization method is utilized for angular and energy information. We also present differential cross-sections for the (dd$\rightarrow$dpn) breakup reaction within \textit{dp} quasi-free scattering limit and their comparison with first calculations based on Single Scattering Approximation (SSA) approach.Comment: 6 pages, 4 figures, presented at Jagiellonian Symposium 2015 in Krakow, PhD wor