Changes in the redox status of the brain in an experimental glaucoma model

The purpose of this study was to evaluate the redox status changes of primary visual targets in the rat brain of a high pressure-induced glaucoma model. The animal model consisted of inducing ocular hypertension by cauterizing two episcleral veins on the left eye. The markers of oxidative damage and the oxidative balance evaluated in the brain seven days postoperative were: nitrites concentration, levels of non-enzymatic antioxidants and antioxidant enzymes activity.
The increase in the nitrite content, which could be the result of the enhancement in the production of nitrogen species, and in the activity of NADPH oxidase in the glaucoma group could lead to an increase on lipid and protein damage.
The decrease on the non-enzymatic antioxidants and the compensatory increase of the superoxide dismutase and glutathione peroxidase activities could be a consequence of the increase of oxidative processes. The decrease in the activity of glutathione reductase leads to a decrease in the recycling of thiol groups.
We suggest that oxidative stress can possibly acts as a risk factor for neurodegeneration in the brain. Therapeutic strategies to stop the progression of the disease in glaucoma should also be considered the central neuronal degeneration beyond the retina and the optic nerve.     

TEXTURAL CHANGES IN VEGETABLES DURING THERMAL PROCESSING. I. A DESCRIPTIVE METHOD to SEGREGATE EFFECTS of PROCESS TREATMENTS

Criteria for assessing the effect of processing treatments on the texture of processed foods were developed. Five parameters were defined, relating the hardening or softening of a food material and allowing for the comparison between different processing procedures. In order to determine the usefulness of this method, the parameters were applied to experimental data reported in literature for thermal processing of fruits and vegetables. Three parameters were defined for identifying the effect of a given preprocessing treatment on the raw material texture, the effect of the preprocessing treatment on the sensitivity of the vegetable tissue to the thermal processing and the overall effect. the two remaining parameters were used to describe additional information regarding the process kinetics, that is, to assess the effect of time and temperature on the rate of softening/hardening.     

Analytical Method for Determination of Some Aroma Compounds on White Wines by Solid Phase Microextraction and Gas Chromatography

ABSTRACT A method for analyzing volatiles such as alcohols (1-octen-3-ol), aldehydes (trans-trans -2,4-decadienal, trans -2-nonenal), terpenols (linalool, terpineol, and oxides), and isoprenoids (β-damascenone, β-ionone, 1,1,6-trimethyl-1,2-dihydronaphtalen and vitispirane) on white wines using solid phase microextraction has been developed. The analytes were extracted directly from the headspace of a constant volume of wine using 7 different fibers coated with different stationary phases compared with a classic dichloromethane extract. The best extraction efficiency was obtained with a divinylbenzene/Carboxen/polydimethylsiloxane, 50/30 μm. Sample volume, time, and temperature of the extraction were optimized and the matrix effect studied. The limits of quantification varied between 0.013 and 1.81 μg/L. The r-values for linearity studies varied between 0.9761 and 0.9999. Among the compounds measured, some are related to the aroma of young white wine, such as linalol, terpineol, β-damascenone, whereas others, for example, 1-octen-3-ol, trans-trans -2,4-decadienal, trans -2-nonenal, 1,1,6-trimethyl-1,2-dihydronaphtalene, and vitispirane, are related to evolution characteristic of white wines.     

Instrumental Method for Characterizing Protein Foams

A whipping machine for cream analysis (Cream Tester CTII) was used to foam egg white, milk proteins and soy protein isolate. Foam formation and final rigidity were characterized by the current input to the beating motor. In addition, specific volume, rigidity (compressive strength by Instron) and stability (drainage) of the foams were determined by methods that minimized foam damage during handling. Current input during whipping distinguished fresh vs pasteurized egg white and positively correlated with compressive strength of final egg white foams. Such correlation was not found for milk protein and soy protein isolate foams of lower strength and stability.     

EFFECT OF PRODUCT AND PROCESS VARIABLES IN THE FLOW OF SPHERICAL PARTICLES IN A CARRIER FLUID THROUGH STRAIGHT TUBES

Residence time of particles and fluid-to-particle heat transfer coefficient, two of the major unknowns in the aseptic processing of particulate fluid foods, are intimately related with the linear and rotational velocities of the solid particles. These two velocities were measured by videotaping the flow of individual spherical particles in transparent straight tubes. The effect of fluid velocity and viscosity, particle diameter and density and tube diameter and upward inclination was statistically evaluated using a replicated full factorial design at two levels. Particle linear velocities between around one third of the average fluid velocity and 15% higher were obtained. Rotational velocities were usually lower, but of the same order of magnitude. Particle density and particle diameter had a significant effect on the two particle velocities analysed. The effect of fluid velocity was     

PURIFICATION AND PARTIAL CHARACTERIZATION OF A LECTIN FROM THE SEEDS OF DIOCLEA GUIANENSIS1

A lectin was purified from seeds of Dioclea guianensis by Sephadex G-50 affinity chromatography. Apparent homogeneity of the lectin was demonstrated by native polyacrylamide gel electrophoresis, chromatography on DEAE- and CM-Sepharose, and immunochemistry. The lectin showed a carbohydrate specificity for D-mannose (D-glucose)-binding, had a requirement for Ca^?2 and Mn^?2, contained no covalently bound carbohydrate and had an amino acid composition characterized by high content of aspartic acid, serine and threonine, and low levels of sulfur-containing amino acids. At pH 7.5 it exists as two species of molecular weight about 100 and 47 kD and in dissociating solvents three subunits of approximate size of 30, 18 and 12 kD were obtained. The lectin agglutinated erythocytes from rabbit and chicken but not from human, cow, sheep, goat or pig and was toxic to brine shrimp (Artemia salina) larvae. It was relatively heat-stable, retaining half of its original activity even after 90 min at 70°C.     

APPLICATION OF A NEW CONTINUOUS FLOW SPECTROPHOTOMETRIC METHOD FOR THE CHARACTERIZATION OF POLYPHENOL OXIDASE NATURALLY IMMOBILIZED ON COCONUT FIBER

The association of continuous flow injection and spectrophotometry affords a simple, novel and rapid way of monitoring continuously the activity of naturally immobilized enzymes in their natural environment, thus eliminating cumbersome purification. The method was applied to determine the activity of polyphenol oxidase (PPO) enzymes naturally immobilized on coconut (Cocus nucifera, L.) fiber tissues. Maximum enzyme activity occurred at a temperature of 25C and at pH 6.0 using catechol as substrate. Thermal stability was assayed in a temperature range of 20 to 75C. The PPO exhibited excellent thermal stability, with only 50% loss in its activity at 75C after 4.3 min exposure. For catechol apparent Michaelis‐Menten constant (apparent Km), apparent Vmax and the apparent activation energy were 9.1 × 10^?3 mol L^?1, 0.20 abs min^?1 and 10.5 kcal mol^?1, respectively. The immobilized PPO showed high activity for o‐diphenols. The reactivity order was caffeic acid > pyrogallol > catechol. Complete inhibition of the enzyme was observed with 1 × 10^?3 mol L^?1 concentration of cyanide, thiourea, L‐cysteine, ascorbic acid, sodium sulfite, nitrates of cadmium, zinc and mercury, individually. Benzoic acid, 3‐hydroxy‐benzoic acid, 4‐acetamidephenol, sodium azide, resorcinol, L‐cystine and EDTA at equal concentrations inhibited PPO partially.