Modified peroxiredoxins as prototypes of drugs with powerful antioxidant action

The possibility of using modified peroxiredoxins as powerful antioxidant agents has been considered. Peroxiredoxins immobilized on perfluorocarbon emulsions and PTD-modified peroxiredoxins have been studied. It has been shown that peroxiredoxins efficiently bind to particles of perfluorocarbon emulsions, while maintaining their antioxidant properties. A panel of PTD-modified peroxiredoxins has been created and peroxiredoxins most effective both in antioxidant properties and the ability to penetrate cells have been selected. The modified peroxiredoxins obtained may serve as the basis for the design of drug with powerful antioxidant action.     

Diminution of phagocytosed perfluorocarbon emulsions using perfluoroalkylated polyethylene glycol surfactant

Perfluorocarbon emulsions have been considered as potential blood substitutes for years due to their high capacity of dissolving respiratory oxygen and carbon dioxide. However, they have been reported to associate with side effects (e.g., flu-like syndrome) after being injected into animal's bloodstream. The cause of these side effects is related to the phagocytosis of perfluorocarbon emulsions by cells (e.g., macrophages). Inspired by the approach of using polyethylene glycol (PEG) to camouflage liposomes, we synthesized a perfluoroalkylated PEG (R(F)-PEG) surfactant to provide steric hindrance for decreasing phagocytosis of perfluorocarbon emulsions. The R(F)-PEG surfactant along with Pluronic F-68 and egg yolk phospholipid mediated perfluorocarbon emulsions were incubated individually with J774A.1 macrophages to examine the degree of phagocytosis. 19F NMR studies were used to quantitatively determine the amount of perfluorocarbon emulsions phagocytosed by macrophages. Results showed that the degree of phagocytosis was diminished to a large extent for perfluorocarbon microparticles emulsified by the R(F)-PEG surfactant.     

Perfluorocarbons as oxygen-transport fluids

1. An overview of the proposed biological applications of perfluorocarbons and their emulsions as oxygen-transport fluids is presented. 2. Aspects of the properties, preparation, composition and physiological assessment of perfluorocarbon emulsions are discussed. 3. The experimental basis for some of the potential therapeutic uses of PFCs in liquid ventilation, treatment of decompression sickness, organ perfusion, oxygenation of ischaemic and malignant tissues, and as contrast media for NMR imaging is described. 4. The extent to which emulsified perfluorocarbons may have value as substitutes for red blood cells is discussed in detail. Data from both animal and human studies with such emulsions is reviewed. Brief consideration is also given to the possible use of native and modified haemoglobin in blood replacement together with recent work on the preparation of so-called "synthetic red cells".     

Use of perfluorocarbon emulsions in cell culture.

Perfluorocarbon emulsions were applied to hybridoma cultures grown in tissue culture tubes and column bioreactors. The oxygen transfer enhancement effect of perfluorocarbon emulsions was clearly demonstrated by the higher cell densities obtained in emulsion-supplemented systems. In addition, perfluorocarbon emulsions were shown to provide better cell suspension in a low-shear environment. The study in column bioreactors also suggested a cell protective effect of the employed perfluorocarbon emulsions in reducing the damage to cells by gas bubbles.     

Function of the mononuclear phagocyte system after administration of emulsions of perfluorinated carbon compounds

Morpho-functional characteristics of mononuclear phagocyte system (MPS) have been studied in experimental animals upon the infusions of perfluorocarbon (PFC) emulsions. It has been established that the infusion of high doses of PFC emulsions following massive hemorrhage causes the reduction in the histoenzymatic activity in MPS of PFC-accumulating organs. Low doses of PFC emulsions increase histochemical activity in PFC-containing macrophages, suggesting a stimulating effect of PFC emulsions on MPS.     

Effect of the interfacial surfactant layer on oxygen transfer through the oil/water phase boundary in perfluorocarbon emulsions

The effect of interfacial surfactant molecules on oxygen transfer through oil/water phase boundary has been studied in FlurO(2) (TM) emulsions, i.e., perfluorocarbon (PFC) emulsions developed as oxygen carriers in cell culture. Measurements of oxygen permeability were made with a polarographic oxygen electrode in pure PFCs and in emulsions with various PFC volume fractions. Comparison of the experimental results with the theoretically derived values of relative oxygen permeability clearly indicates that the mass transfer resistance caused by the interfacial surfactant layer in PFC emulsions is insignificant. Therefore, oxygen dissolved in the enclosed PFC phase is readily available to cells growing in the aqueous media and FlurO(2) emulsions with very fine emulsion particles (< 0.2 mum) can be used to effectively enhance gas/liquid interfacial oxygen transfer in bioreactors. The inadequacy in describing mass transfer in heterogeneous systems, such as the PFC emulsions, by conventional concentration-based oxygen diffusion coefficients has also been discussed.     

Biosurfactants: Production and application prospects in the food industry

There has been considerable interest in the use of biosurfactants due to the diversity of structures and the possibility of production from a variety of substrates. The potential for industrial applications has been growing, as these natural compounds are tolerant to common processing methods and can compete with synthetic surfactants with regards to the capacity to reduce surface and interfacial tensions as well as stabilise emulsions while offering the advantages of biodegradability and low toxicity. Among biosurfactant-producing microorganisms, some yeasts present no risks of toxicity or pathogenicity, making them ideal for use in food formulations. Indeed, the use of these biomolecules in foods has attracted industrial interest due to their properties as emulsifiers and stabilizers of emulsions. Studies have also demonstrated other valuable properties, such as antioxidant and antimicrobial activity, enabling the aggregation of greater value to products and the avoidance of contamination both during and after processing. All these characteristics allow biosurfactants to be used as additives and versatile ingredients for the processing of foods. The present review discusses the potential application of biosurfactants as emulsifying agents in food formulations, such as salad dressing, bread, cakes, cookies, and ice cream. The antioxidant, antimicrobial and anti-adhesive properties of these biomolecules are also discussed, demonstrating the need for further studies to make the use of the natural compounds viable in this expanding sector.     

Biophysics at the turn of the new millenium: perfluorocarbon media and gas-transporting blood substitutes

The results of 20-year investigations of perfluorocarbon gas-transporting emulsions for biological and medical applications performed by russian biophysicists together with chemists and clinicists are reviewed. As a result of these investigations, the blood substitute perftoran was created. Now this commercial blood substitute has different applications in clinics of Russia and other countries.     

Enhanced reduction of nitrous oxide by Pseudomonas denitrificans with perfluorocarbons

Nitrous oxide reduction and nitrogen production by Pseudomonas denitrificans, as well as culture growth rates all increased 2-3 fold when cultured in the presence of perfluorocarbon emulsions (10% v/v) as compared to control cultures grown in the absence of perfluorocarbons. Initial nitrous oxide concentrations for consecutive experiments were 0.7 and 1.2 mM respectively.     

Effects of perfluorodecalin and perfluorooctylbromide emulsions on peak contractile force and ATP levels in the guinea pig left atrium.

The isolated, electrically-driven, guinea pig left atrium was used to study the ability of two perfluorocarbon emulsions to prevent anaerobic hypofunction in the myocardium. A 20% perfluorodecalin (PFD) emulsion maintained peak tension at 80% of aerated levels for more than 20 minutes. Emulsions of perfluorooctylbromide (PFOB) ranging from 25 to 100% produced a similar result, except that the 25% emulsion could not maintain contractions for the entire time period. Peak tension of atria bathed in K-H solution decreased to less than 50% over the same time period. Both 20% PFD and 100% PFOB maintained myocardial ATP levels at pre-hypoxic levels for at least twenty minutes after aeration was terminated. Unaerated atria, bathed in Krebs-Henseleit solution only, exhibited a significant decline in tissue ATP levels at this time. It appears that perfluorocarbon emulsions may delay oxygen desaturation and thereby protect cardiac tissue from ATP depletion and impaired cardiac function associated with hypoxia. This tissue preparation was found to be very useful for determining the efficacy of potential oxygen carriers.     

The use of affinity adsorbents in expanded bed adsorption

The potential for the use of affinity ligands in expanded bed adsorption (EBA) procedures is reviewed. The use of affinity ligands in EBA may improve its use in direct recovery operations, as the enhanced selectivity of the adsorbent permits selective capture of the target from complex feedstocks and high degrees of purification. The properties of ligands suitable for use in EBA processes are identified and illustrated with examples. In addition to its use in the recovery of soluble products, such as proteins and nucleic acids, from particulate feedstocks, EBA can also be used to recover particulate entities, such as cells and packaged DNA (viruses and phages), from feedstocks. Affinity ligands coupled to appropriate chosen support materials will be required for such processes in order to achieve the necessary selectivity for the required particulate entity. The latter point is illustrated by the use of proteinaceous ligands immobilized to perfluorocarbon emulsions to achieve separations of microbial cells.     

Antioxidant Activity of Diethyldithiocarbamate

Diethyldithiocarbamate (DDC), a potent copper chelating agent, has long been used for the treatment of oxygen toxicity to the central nervous system, as an immunomodulator to treat cancer, and in HIV-infected patients. We evaluated the antioxidant properties of DDC, including its scavenging of reactive oxygen species, its reducing properties, its iron-chelating properties, and its protective effects on oxidant-induced damage to brain tissue, protein, human LDL, and DNA. It is found that DDC is a powerful reductant and antioxidant since it scavenges hypochlorous acid, hydroxyl radical and peroxynitrite; it chelates, then oxidizes ferrous ions; it blocks the generation of hydroxyl radicals and inhibits oxidative damage to deoxyribose, protein, DNA, and human LDL. These findings may provide an explanation for the apparent beneficial effects of DDC against oxidative stress-related diseases that have been observed in experimental and clinical studies.     

Antifreeze Emulsions Produced from Linoleic Acid and Water Using Enzymatically Modified Gelatin

An enzymatically modified gelatin with covalently attached leucine dodecyl ester, referred to as EMG-12, was used as a surfactant to prepare emulsions with different properties by changing the surfactant concentration, oil volume fraction, and pH in the water phase. The emulsions generally resisted the freezing of their constituent bulk water at approximately ?10°C, but similar emulsions produced with soy protein isolate, casein, or Tween-80 as control agents were less resistant. The freezing (or unfreezing) of the bulk water in these emulsions depended on the kind of agent used, not on the emulsion properties such as average area of the oil/water interface, stability against coalescence, and stability against creaming. The emulsion produced with EMG-12, like that produced with polyglycerol stearate, tended to maintain its unfrozen state even in the presence of silver iodide crystals added as heterogeneous ice-nuclei. The significance of producing such an antifreeze emulsion is discussed from the standpoint of cryopreservation of cold-sensitive food and biological systems.     

New perfluorocarbon system for multilayer growth of anchorage-dependent mammalian cells.

A novel tissue culture system has been developed that supports the multilayer growth of Hep G2 cells. The system consists of growing cells on collagen-coated perfluorocarbon substrata in the wells of a multi-well plate designed so that, even at very high densities, the oxygen in the cultures is replenished as rapidly as it is consumed. Hep G2 cells, which are typically contact inhibited, grow to form more than 10 layers of cells that continue to secrete albumin. Both multilayer growth and high rates of albumin depend on using a very enriched nutrient medium, compared to media usually used for monolayer culture of Hep G2 cells. The role played by increased oxygenation, enriched media, and the unique properties of the perfluorocarbon substrata for the 3-D growth of anchorage-dependent cells is discussed.     

Peroxidation of lipid emulsions: a hazard for the premature infant receiving parenteral nutrition?

Lipid emulsions for parenteral use are peroxidized during storage, indicating that the amount of the natural vitamin E in the preparations is inadequate. Peroxidation products in the lipid emulsion preparations can induce cell damage in vitro. The parenteral administration of lipid emulsions increases in vivo lipid peroxidation in adult and healthy newborn patients as well as in premature infants, whereas enteral feeding seems to lead to a more balanced accretion of polyunsaturated fatty acids. The use of parenteral lipids has recently been associated with increased morbidity of premature infants. Current opinion favors the view that evolution of the complications is highly influenced by the inferior defense of the premature infants to resist oxidant loads. A novel antioxidant added in the preparations for the intravenous provision of polyunsaturated lipids could be beneficial for such patients.     

Note: Antioxidant properties of lipid fractions from Deinococcus radiophilus strain UWO1055

Lipids of the radio-resistant bacterium Deinococcus radiophilus were tested for their antioxidant properties. The crude lipid extract showed a significant antioxidant effect in linoleic acid emulsion. The crude extract was separated to polar and non-polar lipid fractions. The non-polar fraction showed an antioxidant effect in both suspensions and emulsions of linoleic acid, and inhibition of oxidation in a β-carotene emulsion. Lipids of the non-polar fraction were separated and their antioxidant activity was determined in a β-carotene emulsion; the lipid that was marked NP9 showed the highest antioxidant effect. Lipid NP9 inhibited oxidation in a β-carotene emulsion in the concentration range of 5–51 ppm. It is suggested that the antioxidant activity of lipids of D. radiophilus contribute to its radio-resistance.     

Hard shell gas-filled contrast enhancement particles for colour Doppler ultrasound imaging of tumors

Hollow hard shell particles of 200 nm and 2 micron diameter with a 10 nm thick porous silica shell have been synthesized using polystyrene templates and a sol-gel process. The template ensures than the hollow particles are monodispersed, while the charged silica surface ensures that they remain suspended in solution for weeks. When filled with perfluorocarbon gas, the particles behave as an efficient contrast agent for colour Doppler ultrasound imaging in human breast tissue. The silica shell provides unique properties compared to conventional soft shell particles employed as ultrasound contrast agents: uniform size control, strong adsorption to tissue and cells immobilizing particles at the tissue injection site, a long imaging lifetime, and a silica surface that can be easily modified with biotargeting ligands or small molecules to adjust the surface charge and polarity.     

Characteristic properties of N-Carboxybutyl chitosan

N-Carboxybutyl chitosans obtained from levulinic acid (4-oxo-pentanoic acid) and five crustacean chitosans (heteropolymers of N-acetylglucosamine and glucosamine) have been instrumentally characterized and found to have degree of N-carboxyalkylation 0·27. They dissolve in water and in water-ethanol mixtures without the need of any acid and give more viscous solutions than the corresponding chitosans. Their compatibility with other polymers and with salts has been surveyed, and the soluble chelates of Cr(III) and Pb(II) have been studied. The bacteriostatic activity of the N-carboxybutyl chitosans, together with other favorable properties, such as the viscosifying action, the enhanced film-forming ability, the moisturizing effect and the stabilization of emulsions, make these novel modified chitosans most suitable as functional cosmetic ingredients.     

Preparation of stimulus responsive multiple emulsions by membrane emulsification using con a as biochemical sensor

In this work, a novel strategy for the controlled fabrication of biomolecular stimulus responsive water-in-oil-in-water (W/O/W) multiple emulsion using the membrane emulsification process was investigated. The emulsions interface was functionalized with a biomolecule able to function as a receptor for a target compound. The interaction between the biomolecular receptor and target stimulus activated the release of bioactive molecules contained within the structured emulsion. A glucose sensitive emulsion was investigated as a model study case. Concanavalin A (Con A) was used as the biomolecular glucose sensor. Various physicochemical strategies for stimulus responsive materials formulation are available in literature, but the preparation of biomolecule-responsive emulsions has been explored for the first time in this paper. The development of novel drug delivery systems requires advanced and highly precise techniques to obtain their particular properties and targeting requirements. The present study has proven the flexibility and suitability of membrane emulsification for the preparation of stable and functional multiple emulsions containing Con A as interfacial biomolecular receptor able to activate the release of a bioactive molecule as a consequence of interaction with the glucose target molecule. The influence of emulsion interfacial composition and membrane emulsification operating conditions on droplets stability and functional properties have been investigated. The release of the bioactive molecule as a function of glucose stimulus and its concentration has been demonstrated.     

Synthesis of 2'-O-modified adenosine building blocks and application for RNA interference

RNA-interference has been recognized as a powerful tool to control gene function and has been used for gene silencing by knocking down mRNA. Chemically modified RNAs, especially 2'-O-modification, successfully improved their physicochemical and pharmaceutical properties such as stability, nuclease resistance and delivery. Here, we report the synthesis of adenosine building blocks with different 2'-tethered modifications like aminoethyl and guanidinoethyl and show that they are compatible with RNAi function. They enhance the half life of the siRNA in serum suggesting that these modifications can enhance the pharmacokinetic properties and knock down activity of siRNAs in vivo.