Biomedical subjects

Estera Szwajcer Dey

Publications and source records attributed to Estera Szwajcer Dey.

9 recordsLinked to original sources

PubMed2005

A novel procedure for the isolation of glycolipids from Bifidobacterium adolescentis 94 BIM using supercritical carbon dioxide.

This study describes a novel isolation procedure for major glycolipids from Bifidobacterium adolescentis 94 BIM. The procedure consists of the use of supercritical carbon dioxide (scCO(2)) with hydro-methanolic solution as co-solvent. The major glycolipids were isolated using the following operating conditions: pressure, 30 MPa, co-solvent concentration, 10% (9:1, methanol/water, v/v), CO(2) flow rate, 5 g/min, extraction time and temperature, 2h and 55 degrees C, respectively. The reference glycolipids sample was prepared by classical organic solvent extraction followed by chromatographic purification. All isolates were characterized by TLC and the major glycolipids additionally by enzyme linked immunosorbent (ELISA). Sixty milligrams of glycolipids with similar immunoreactivity as the reference glycolipids were isolated from 1g of freeze-dried biomass (6% of yield).

Bifidobacterium↗

PubMed2005

Extraction of rye bran by supercritical carbon dioxide: influence of temperature, CO2, and cosolvent flow rates.

Process parameter optimization for the supercritical CO(2) extraction of rye bran to obtain alkylresorcinols (AR) was studied by carrying out a two-level fractional design experiment. Four parameters, temperature, CO(2) flow rate, cosolvent percentage, and extraction time, presumed to influence the extraction process, were analyzed. A tentative fractionation of the crude extract was also carried out and is discussed. The best extracts were achieved when the CO(2) flow rate and extraction time or temperature and cosolvent addition were kept high. It was found that temperature increase was not statistically significant within the range of the study performed, and the extraction time was thus the most important factor. A preliminary fractionation process in two cyclone separators yielded two fractions, one rich in AR components with higher molecular weights and the other rich in AR components with low molecular weight.

Carbon Dioxide↗

PubMed2005

Improvement of NaNO2-oxidizing activity in Nitrobacter vulgaris by coentrapment in polyacrylamide containing polydimethylsiloxane copolymer and DEAE-sephadex.

Removal of nitrite and nitrate from drinking water has attracted great attention in recent years because of the human health risk induced by the exposure to contaminated groundwater and surface water. We have therefore tested a model nitrite oxidation system by coentrapping the NaNO2 oxidizer Nitrobacter vulgaris with polydimethylsiloxane (PDMS) copolymer and DEAE-Sephadex in a polyacrylamide gel. The copolymer and the anion exchanger facilitate the diffusion of oxygen and NaNO2, respectively, into the gel matrix. To test the nitrite-oxidizing activity, the entrapped cells were coupled to a thermal sensor. Coentrapment of 5% (wt/vol) DEAE-Sephadex with Nitrobacter vulgaris increased the nitrite-oxidizing activity by a factor of 3.7 compared to entrapped cells alone, and by the addition of 0.86% (wt/vol) artificial oxygen carrier PDMS copolymer increased the activity further to 4.3 times higher. Operational and storage stability of the coentrapped N.vulgaris also improved. This suggests that this enhanced immobilized cell system can also be used for nitrite oxidation to nitrate in drinking water as an on-line thermally monitored bioreactor.

Acrylic Resins↗

PubMed2005

The cytotoxic and genotoxic effects of conjugated trans-2-nonenal (T2N), an off-flavor compound in beer and heat processed food arising from lipid oxidation.

This study investigates the toxic effect of E(2)nonenal (trans-2-nonenal, T2N) and its conjugate with horse muscle myoglobin (Mb) tested on murine cell line L929 and human cell line A549, as well as the genotoxic effect of these compounds assayed by measuring of micronuclei in human cells K562. It is an aldehyde, which is occurring as the substance responsible for an off flavour in aged beers, but originates also from lipid oxidation in heat processed food. T2N is an aldehyde formed from linoleic acid as a secondary oxidation product. The modification of Mb with T2N was analyzed with the use of SDS-polyacrylamide gel electrophoresis (SDS-PAGE), and electrospray ionization mass spectrometry (ESI-MS). Results from SDS-PAGE suggest that T2N substitutes Mb and additionally causes cross-linking with polymerization of Mb resulting in an insoluble fraction. The ESI-MS spectrum of the soluble fraction used in the toxicity tests, demonstrated that conjugation of T2N with Mb yielded Mb adducts with one residue of trans-2-nonenal per myoglobin molecule as the major fraction and adducts with different numbers of T2N molecules as minor fractions. In the cytotoxicity assay the T2N and its Mb conjugate causes 50% destruction of cells at the concentration 95-125 microg/ml and 200 microg/ml respectively, when L929 and A549 cell lines were used, whereas Mb control tested up to 2000 mg/ml was without any cytotoxic effect. In genotoxicity in vitro assay we have observed that the T2N and its Mb conjugate expressed the genotoxicity. The number of micronuclei in human K562 cells reached 26 +/- 2.16 promille (MN/1000 cells), comparing to 62 +/- 8.64 MN/1000 cells for the reference free T2N, whereas a control value was 10.33 +/- 1.25 MN/1000 cells. The studied compounds expressed also the apoptotic effect in K562 cells as the number of apoptotic cells increased to 44.67 +/- 4.92 promille for T2N-Mb, comparing to 168.67 +/- 37.28 promille for free T2N, whereas a control value was 30.33 +/- 1.36 promille for Mb. In these assays the T2N-Mb conjugate is several times more toxic in relation to control protein. Results indicate that T2N adducts with protein are potent to induce various cytotoxic and apoptotic effects when assayed in vitro tests. It suggests that higher level of such aldehyde might create in organism severe potential of toxicity.

Aldehydes↗

PubMed2004

Novel peptide surface for reversible immobilization of concanavalin A.

Concanavalin A (Con A) was spontaneously adsorbed on polymyxin B surface. This peptide-lectin interaction was strong, K(D)=1.9 x 10(-10), based predominantly on creation of hydrophobic bonds, and was completely reversible. Concanavalin A on polymyxin B (PmB) retained higher binding capacity for yeast mannan, compared with covalently immobilized lectin. Kinetics of mannan-concanavalin A interaction were significantly different in dependence on type of concanavalin A immobilization.

Adsorption↗

PubMed2004

Poly(3-hydroxybutyrate) biosynthesis in the biofilm of Alcaligenes eutrophus, using glucose enzymatically released from pulp fiber sludge.

Glucose, enzymatically released from pulp fiber sludge, was combined with inorganic salts and used as a growth medium for Alcaligenes eutrophus, a gram-negative strain producing poly(3-hydroxybutyrate) (PHB). By controlling the concentrations of the inorganic salts in the growth medium, almost 78% of the cell mass was converted to pure PHB. Efforts were made to find conditions for bacterial growth in the form of a biofilm on a cheap and reusable carrier. A number of positively charged carriers were tested, and the anion exchanger DEAE-Sephadex A-25 was chosen as a microcarrier for packed-bed biofilm cultures of A. eutrophus. Conditions for attachment, growth, and detachment were established. Biofilm formation on the microcarrier is strongly dependent on the ionic strength of the attachment medium. In order to achieve formation of the biofilm and its recovery from the microcarrier, the ionic strengths of the attachment and the detachment media were varied. Low ionic strength was tested for attachment, and high ionic strength was tested for detachment. Although biofilm formation in the packed-bed reactor is limited, the volumetric yield of cells based on the void volume of the packed bed is comparable with the batch culture yield.

Biofilms↗

PubMed2004

Optical lectin based biosensor as tool for bacteria identification.

Biosensor techniques are based on biospecific interaction between the biological parts of biosensor with the analyte. In biosensor construction, antibodies are usually used for the detection of analytes such as microorganism, because of very strong and highly specific interaction. The disadvantages of this assay are a long time needed for antibody isolation and purification as well as difficult regeneration of biosensor chip. The use of lectins instead of antibodies could solve these problems because a several hundred lectins are commercially available and their stability in standard buffers is better compared to monoclonal antibodies. While antibody can only be used to detect that antigen it was designed for, lectin as low affinity molecule may bind several different pathogens. Using the discriminative effect of an artificial neural network the application of a lectin array will compensate for the lower specificity. Microbial surfaces bear many of the sugar residues capable of interacting with lectins. The ability of lectins to react with microbial glycoconjugates means that it is possible to employ them as probes and sorbents for whole cells, mutants and numerous cellular constituents and metabolites, and it makes them useful tools for identification or typing of bacteria. Lectins are attractive reagents for the clinical diagnostic laboratory because of their diverse specificity, commercial availability, a wide range of molecular weights, and their stability in standard buffers. The construction of lectin biosensor could be an advantage method for detection of pathogenic bacteria.

Animals↗

PubMed2003

Protein fraction of barley spent grain as a new simple medium for growth and sporulation of soil actinobacteria.

A cheap value-added product, the protein fraction of barley spent grains is proposed as a source of a potential and economical cultivation medium. We showed that medium composed of protein fraction extract allows the isolation of actinobacteria, especially Streptomyces, from soil samples, and enhances the sporulation. It was used for the screening and production of the biologically active substances from actinobacteria.

Actinobacteria↗

PubMed2003

Supercritical fluids as alternative, safe, food-processing media: an overview.

The continuous growth of world population and its concentration in the urban areas require food supplies that are continuous, sufficient and of good quality. To resolve this problem techniques have been developed for increasing food quantity and quality. The techniques are applied throughout the food chain from production, conservation and during distribution to the consumers (from "the field to the fork"). During handling of food, chemicals are often deliberately added to achieve improved processing and better quality. This is one of the main reasons food undergoes different kinds of contamination. This overview focuses on the application of supercritical fluids as media for handling food materials during processing with the perspective of reducing chemical contamination of food. Examples of developmental applications of this technique and on research work in process are presented. Emphasis is given to extraction and biotransformation techniques.

Carbon Dioxide↗