Determination of 4-hydroxynonenal by high-performance liquid chromatography with electrochemical detection

4-Hydroxy-trans-2-nonenal (HNE) is a highly reactive product of lipid peroxidation originating from the breakdown of phospholipid-bound polyunsaturated fatty acids of cellular membranes. Despite its biological relevance, this aldehyde is only occasionally determined due to the complexity of previously described procedures. Here we present a simple and very sensitive method for the detection of HNE in biological samples. The method is based on the measurement of the 2,4-dinitrophenylhydrazone (DNPH) of the aldehyde by electrochemical detection after separation by reverse-phase high-performance liquid chromatography (HPLC). The greater sensitivity of this procedure as compared to the ultraviolet detection method commonly employed to measure DNPH derivatives of aldehydes after HPLC will allow the detection of HNE below the pmol level. The detection of HNE is highly reproducible even in normal tissues and cells. Increased amounts of HNE were detected in the livers of animals intoxicated with prooxidant agents such as carbon tetrachloride, bromotrichloromethane or bromobenzene. An exponential increase in HNE (and in malondialdehyde) was measured in peroxidizing liver microsomes (in the NADPH/Fe-dependent system). The method is also suitable for the study of very small samples, since HNE could be detected in approximately 1 million cultured cells (polyoma virus-transformed baby hamster kidney fibroblasts); the level rose after exposure of the cells to a Fe³⁺/ADP prooxidant system. During the course of these studies, Dr. Goldring was on leave from Division of Biochemistry, UMDS Guy's Hospital, London SE1 9RT, UK.     

The influence of powder morphology on the effect of rosemary aroma microencapsulation during spray drying

The influence of particle morphology of spray dried powders obtained by using different carriers on the efficiency of microencapsulation of rosemary aroma is shown in the present research. It was found that the type of the carrier influenced the size but not the shape of rosemary aroma capsules and all the capsules were spherical with cracks. The biggest particles, d₅₀ = 55 μm, were obtained with 25% maltodextrin (MD) as a carrier, and the smallest, d₅₀ = 29 μm with 30% gum arabic (GA). The efficiency of encapsulating aroma inside of the capsules depended on the particles size and apparent density. An increase in the quantity of microencapsulated aroma from 10% for 25% MD to about 60% for 30% GA as the carrier was seen, which co‐related with a decrease in the average diameter of the powder particles. Similarly, an increase in the efficiency of aroma retention was followed by an increase of apparent density of powders from 796 (25% MD) to 1156 kg m^?3 (30% GA).     

Measurement of lipid peroxidation in vivo: A comparison of different procedures

A study was undertaken to investigate whether some of the methods commonly used to detect lipid peroxidation of cellular membranes in vivo correlate with each other. The study was performed with the livers of bromobenzene-intoxicated mice, in which lipid peroxidation develops when the depletion of glutathione (GSH) reaches a threshold value. The methods tested and compared were the following: i) measurement of the malondialdehyde (MDA) content of the liver; ii) detection of diene conjugation absorption in liver phospholipids; iii) measurement of the loss of polyunsaturated fatty acids in liver phospholipids; and iv) determination of carbonyl functions formed in acyl residues of membrane phospholipids as a result of the peroxidative breakdown of phospholipid fatty acids. Correlations among the values obtained with these methods showed high statistical significances, indicating that the procedures measure lipid peroxidation in vivo with comparable reliability. Analogously, the four methods appeared also to correlate when applied to in vitro microsomal lipid peroxidation.     

Vibration characteristics of a cooling-tower shell

The work reported herein deals with problems of experimental method and the analysis of results in an investigation of the dynamic properties of a real cooling tower. Analysis of the most important experimental results has been completed. The experimental data are compared with theoretical results obtained using a finite-element method of solution.     

Developing Negotiation Decision Support Systems that Support Mediators: A Case Study of the Family_Winner System

Negotiation Support Systems have traditionally modelled the process of negotiation. They often rely on mathematical optimisation techniques and ignore heuristics and other methods derived from practice. Our goal is to develop systems capable of decision support to help resolve a given dispute. A system we have constructed, Family_Winner, uses empirical evidence to dynamically modify initial preferences throughout the negotiation process. It sequentially allocates issues using trade-offs and compensation opportunities inherent in the dispute.     

High-throughput screening of protein surface activity via flow injection analysis-pH gradient-dynamic surface tension detection

Using flow injection analysis (FIA), a pH gradient is blended in real time with a protein sample as the pH-dependent protein surface activity is measured by a dynamic surface tension detector (FIA-pH-DSTD). This instrumental system was developed as a high-throughput method for the screening of protein surface activity at the air/liquid interface as a function of pH. This method utilizes the continuous flow, drop-based dynamic surface tension detector in combination with flow injection sample introduction and blending of a steady-state concentration of protein sample with a pH gradient ranging from pH 2.0 to pH 11.5. Dynamic surface tension is measured through the differential pressure across the air/liquid interface of repeatedly growing and detaching drops. Continuous surface tension measurement is achieved for each eluting drop of 2-s length (2 muL), providing insight into both the kinetic and thermodynamic behaviors of molecular orientation processes at the liquid/air interface. Three-dimensional data are obtained, with surface tension first converted to surface pressure, which is collected as a function of elution time versus drop time. In FIA-pH-DSTD, a commercial pH probe is used to measure pH during elution time, enabling surface pressure throughout drop time to be subsequently plotted as a function of eluting pH. An automated DSTD calibration procedure and data analysis method is applied, which allows simultaneous use of two different solvents, permitting real-time dynamic surface tension data to be obtained. The method was applied to the analysis of 14 commercial purified proteins, yielding characteristic features of surface activity as a function of pH. The reproducibility of the measurement and selectivity advantage of the DSTD was shown for the analysis of serum albumins from various mammalian sources. Several applications were also suggested and discussed in order to show the potential of the method for protein and food chemistry studies and in the study of protein-polymer interactions.     

Nutritional, textural and sensorial characterisation of Italian table olives (Olea europaea L. cv. 'Intosso d'Abruzzo')

In the present study, we evaluated chemical, nutritional, sensory and textural characteristics of table olives of an Italian double-aptitude olive cultivar ( Olea europaea  L. cv. Intosso d'Abruzzo ). The aim of this work was to focus some physico-chemical characteristics of this end product in order to enhance the value of this fruit from a nutritional point of view. These table olives are fruits with an appreciable content of fibre (2.6 g/100 g) and natural antioxidants such as polyphenols (167.8 mg/100 g) and α-tocopherol (6.44 mg/100 g). In this cultivar, oil content is high (17.5 g/100 g), such as MUFA (13.6 g/100 g). The protein content is low (1 g/100 g), but nutritional quality is high for the presence of essential amino acids.     

Nanoshells with Targeted Simultaneous Enhancement of Magnetic and Optical Imaging and Photothermal Therapeutic Response

Integrating multiple functionalities into individual nanoscale complexes is of tremendous importance in biomedicine, expanding the capabilities of nanoscale structures to perform multiple parallel tasks. Here, the ability to enhance two different imaging technologies simultaneously—fluorescence optical imaging and magnetic resonance imaging—with antibody targeting and photothermal therapeutic actuation is combined all within the same nanoshell‐based complex. The nanocomplexes are constructed by coating a gold nanoshell with a silica epilayer doped with Fe₃O₄ and the fluorophore ICG, which results in a high T₂ relaxivity (390 mM ^?1 s^?1) and 45× fluorescence enhancement of ICG. Bioconjugate nanocomplexes target HER2+ cells and induce photothermal cell death upon near‐IR illumination.     

Arsenic species interactions with a porous carbon electrode as determined with an electrochemical quartz crystal microbalance

The interactions of arsenic species with platinum and porous carbon electrodes were investigated with an electrochemical quartz crystal microbalance (EQCM) and cyclic voltammetry in alkaline solutions. It is shown that the redox reactions in arsenic-containing solutions, due to arsenic reduction/deposition, oxidation/desorption, and electrocatalyzed oxidation by Pt can be readily distinguished with the EQCM. This approach was used to show that the arsenic redox reactions on the carbon electrode are mechanistically similar to that on the bare Pt electrode. This could not be concluded with just classical cyclic voltammetry alone due to the obfuscation of the faradaic features by the large capacitative effects of the carbon double layer.For the porous carbon electrode, a continual mass loss was always observed during potential cycling, with or without arsenic in the solution. This was attributed to electrogasification of the carbon. The apparent mass loss per cycle was observed to decrease with increasing arsenic concentration due to a net mass increase in adsorbed arsenic per cycle that increased with arsenic concentration, offsetting the carbon mass loss. Additional carbon adsorption sites involved in arsenic species interactions are created during electrogasification, thereby augmenting the net uptake of arsenic per cycle.It is demonstrated that EQCM, and in particular the information given by the behavior of the time derivative of the mass vs. potential, or massogram, is very useful for distinguishing arsenic species interactions with carbon electrodes. It may also prove to be effective for investigating redox/adsorption/desorption behavior of other species in solution with carbon materials as well.