Large agarose-lipase beads for the hydrolysis of triglycerides

Summary Pancreatic lipase could be immobilized by binding to large agarose beads or by entrapment within a polyacrylamide polymer. Large agarose beads, prepared from native agarose, were preferred for their higher binding capacity and easy intact separation for reuse. The agarose lipase complex is stable for 6 months at 4 °C and pH 7.5. The immobilized lipase preparation maintained 80% of its initial activity even after reusing it eight times. Consequently, the immobilized lipase was recommended for semicontinuous hydrolysis of olive oil and milk fat trigylcerides. The amount of total hydrolysis was 31 ± 1.17% for milk fat compared with 27 ± 1.03 % for olive oil.

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Große Agarose-Lipase-Kugeln für die Hydrolyse von Triglyceriden

Zusammenfassung Es wurden große Agarosekugeln zur Immobilisierung von Pankreaslipase angewendet. Auf Grund ihrer höheren Aktivität, Stabilität während der Lagerung und ihrer leichten Trennung aus dem Reaktionsgemisch werden sie zur Hydrolyse von Triglyceriden empfohlen. Das Lipasepräparat zeigte nach achtmaliger Verwendung eine Aktivität von 80%. Die gebundene Lipase hydrolisierte innerhalb von 30 min 31,0±1,17% des Milchfettes und 27,1 ± 1,03% des Olivenols.

     

Properties of New Composite Materials Based on Hydroxyapatite Ceramic and Cross-Linked Gelatin for Biomedical Applications

The main aim of the research was to develop a new biocompatible and injectable composite with the potential for application as a bone-to-implant bonding material or as a bone substitute. A composite based on hydroxyapatite, gelatin, and two various types of commercially available transglutaminase (TgBDF/TgSNF), as a cross-linking agent, was proposed. To evaluate the impacts of composite content and processing parameters on various properties of the material, the following research was performed: the morphology was examined by SEM microscopy, the chemical structure by FTIR spectroscopy, the degradation behavior was examined in simulated body fluid, the injectability test was performed using an automatic syringe pump, the mechanical properties using a nanoindentation technique, the surface wettability was examined by an optical tensiometer, and the cell viability was assayed by MTT and LDH. In all cases, a composite paste was successfully obtained. Injectability varied between 8 and 15 min. The type of transglutaminase did not significantly affect the surface topography or chemical composition. All samples demonstrated proper nanomechanical properties with Young’s modulus and the hardness close to the values of natural bone. BDF demonstrated better hydrophilic properties and structural stability over 7 days in comparison with SNF. In all cases, the transglutaminase did not lead to cell necrosis, but cellular proliferation was significantly inhibited, especially for the BDF agent.     

Characterization of a Glycolipid Synthase Producing α-Galactosylceramide in Bacteroides fragilis

Glycolipids are complex molecules involved in important cellular processes. Among them, the glycosphingolipid α-galactosylceramide has proven to be of interest in biomedicine for its immunostimulatory capabilities. Given its structural requirements, the use of ceramide glycosyltransferase enzymes capable of synthesizing this molecule under in vivo or in vitro conditions is a potential production strategy. Several GT4 enzymes from Bacteroides fragilis were considered as potential candidates in addition to the known BF9343_3149, but only this one showed glycolipid synthase activity. The enzyme was expressed as a SUMO fusion protein to produce soluble protein. It is a non-processive glycosyltransferase that prefers UDP-Gal over UDP-Glc as a donor substrate, and maximum activity was found at pH 7.3 and around 30–35 °C. It does not require metal cations for activity as other GT4 enzymes, but Zn²⁺ inactivates the enzyme. The reaction occurs when the ceramide lipid acceptor is solubilized with BSA (100% conversion) but not when it is presented in mixed micelles, and anionic lipids do not increase activity, as in other membrane-associated glycolipid synthases. Further protein engineering to increase stability and activity can make feasible the enzymatic synthesis of α-GalCer for biomedical applications.     

The Effect of Initial Stress on Thermoelastic Rotating Medium with Voids Due to Laser Pulse Heating with Energy Dissipation

This article reports studies on the rotation of initially stressed thermoelastic medium with voids subjected to thermal loading due to laser pulse. The bounding plane surface is heated by a non-Gaussian laser beam. The medium rotated with a uniform angular velocity. The problem was studied in the context of Green-Naghdi (G-N) theory of types II and III using the normal mode analysis method. The comparisons between the both types II and III of (G-N) theory in the presence and the absence of the rotation, the initial stress and for two values of time for considered medium are shown graphically.     

Intensity of electric and magnetic fields from power lines within the business district of 60 Ontario communities

Electric and magnetic fields were measured during the summer of 1998 in south-central Ontario within the business district of 60 communities, ranging in size from 1000 to 2.3 million people. The mean magnetic flux density for the 60 communities was 5.8 mG. Communities with larger populations generally had higher magnetic flux densities than those with smaller populations. Communities with populations above 100,000, between 50,000 and 100,000, between 10,000 and 50,000, and less than 10,000 had mean magnetic flux densities of 14, 7, 4 and 2.4 mG, respectively. The city of Kingston, population 123,000, had the highest mean magnetic flux density (47 mG) while Burks Falls, population 1000, had the lowest (0.8 mG). More than 90% of the sites measured in Kingston, Toronto, Oshawa, London, Pickering Village and Bellville were above 2 mG, the lower limit associated with childhood cancers. In only one community (Burks Falls) were all of the measurements in the business district below 2 mG. Diurnal variations were detected in the magnetic field (but not in the electric field) with highest fields measured during business hours. For electric fields, the mean for the 60 communities was 3.2 V/m. Electric fields were generally low. Eight communities had maximum field strengths above 30 V/m and all of these were associated with overhead wires. In larger communities with underground distribution lines the electric fields were low or undetectable (<0.1 V/m) but the magnetic fields were often high. High electric fields were generally associated with low magnetic fields but the relationship was not sufficiently robust to enable prediction of one from the other. Data for the business district measured during business hours appear to be relatively consistent for both electric field and magnetic flux density over a two-year period. Two classification schemes that can be used independently or in combination are proposed to facilitate community comparisons. One is based on the average intensity of the fields (FI) and the other on the percentage of measurements that exceed a critical limit (CL) that has biological significance. The critical value of 5 V/m is proposed for electric fields and 2 mG for magnetic fields. Both classification schemes use the traffic light analogy for exposure (green-low, amber-medium, red-high exposure) with an additional category (black) for very high exposure. This classification system facilitates information transfer and can easily be understood and used by the public, public utilities, policy makers, and those wanting to practice prudent avoidance.     

Effect of 5-caffeoylquinic acid on soybean oil oxidative stability

The antioxidant activity of 5-caffeoylquinic acid (5CQA) at concentration ranges of 0.01–0.08% (w/w) was compared with 0.02% (w/w) butylated hydroxytoluene (BHT) in soybean oil. The oil was stored in air at 55  °C and monitored by peroxide and conjugated diene measurements. Both 0.01% and 0.02% 5-CQA showed lower peroxide values than BHT only on the first day. However, on days 1, 2, 3 and 4, 0.04% 5-CQA reduced the peroxide value to 68%, 47%, 45% and 90% of that observed with BHT. Use of 5-CQA appears to delay the formation of peroxides and up to 0.04% (w / w) its antioxidative action increases with concentration for up to 3 days.