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Peroxidation of leukocytes index ratio and a functional mathematical index: their potential application in screening of non-communicable diseases
Full text linkThis PhD thesis has been conducted in the context of a project aimed to evaluate the possible use of the PLIR, a test that measures both the resistance of leukocytes to an exogenous oxidative stress and the leukocytes functional capacity of oxidative burst upon activation, as redox marker in humans. The clinical relevance of a biomarker must be critically evaluated before the use in large trials. For the above reason we have planned pilot studies. In order to evaluate the redox status in particular conditions (smoking habit, disease states), ex vivo free-radical production and oxidative stress in body fluids are measured. These methods are used also in human intervention studies to associate the levels of ingested antioxidants (by foods or supplements) with improvement of the body antioxidant status. Despite the fact that it has been suggested that nutraceuticals are capable of improving health, significant methodological bias must be taken into account in the interpretation of data from the measurement of reactive species in leukocytes and platelets by flow cytometry, from the evaluation of markers based on ROS-induced modifications, from the assay of the enzymatic players of redox status, and from the measurement of the total antioxidant capacity of human body fluids. It has been suggested that the bias of each method could be overcome by the evaluation of oxidative stress by using more than one criterion and indexes of redox status have been proposed [Marrocco et al. 2017]. The OXY-SCORE was computed by subtracting the protection score (GSH, alpha- and gamma-tocopherol levels, and antioxidant capacity) from the damage score (plasma free and total malondialdehyde, GSSG/GSH ratio, and urine F2-IsoPs). In some diseases, the choice of the markers that must be considered in the global index should dictate the clinical relevance in the subjects selected. In patients with chronic venous insufficiency (CVI) was used for OXyVen index calculation the normalized and standardized plasma parameters which showed a significant statistical difference between CVI patients and controls (SH, MDA-bound protein, protein carbonyls, and CAT activity). However, the major bias of these index is the use of markers that do not have at the moment normal values. The oxidative-INDEX was calculated by subtracting the OXY (the antioxidant capacity measured with the OXY adsorbent test) standardized variable from the ROM (the reactive oxygen metabolites measured with the d-ROM) standardized variable. Although normal values have been proposed for these variables, the OXY adsorbent test quantifies the ability of the plasma nonenzymatic antioxidant compounds to cope with the in vitro oxidant action of hypochlorous acid (HOCl; an oxidant endogenously produced). This type of approach does not consider the important role of free radicals in the innate response and in the resistance to infection, that declines in some conditions, such as overtraining. Within the total antioxidant capacity assays the FRAP, exploits the same principle of biological antioxidant potential (BAP) (i. e. the reduction of ferric to ferrous ions), matches the antioxidant capacity to the reducing ability. It is well known that reduced iron is critical in the onset of oxidative stress due to the Fenton reaction, that generates the hydroxyl radical initiator of lipid peroxidation. Furthermore, the antioxidant capacity is strongly influenced by UA. The latter is a well known pathogenic factor when at high concentrations. In a previous postprandial study we observed that a functional food covered by dark chocolate and containing glucomannan, inulin, fructooligosaccharides, and Bacillus coagulans strain GanedenBC30 significantly improved postprandial metabolic stress (insulin, glucose, and triglycerides), reduced the postprandial increase of UA, and improved PLIR of lymphocytes, but not of monocytes and granulocytes. We suggested that, although PLIR is a functional index that is independent of baseline levels of oxidation, measuring the ratio between the resistance to exogenous and the resistance to endogenous ROS injury, this ratio calculation could mask the effect of foods that inhibit both the exogenous ROS injury and the oxidative burst.
From that the aims of this thesis were:
1. Evaluate the relationships between PLIR and FRAP, its major endogenous determinant UA and FRAP-UA, by using a GTE due to its reported UA-lowering and potential pro-oxidant effects.
2. Study the relationships between PLIR and a mathematical index that considers health-related habits and UA plasma levels
Effects of red wine on postprandial stress: potential implication in non-alcoholic fatty liver disease development
No full textRed wine consumption is considered to be protective against oxidative stress. Diet strongly influences non-alcoholic fatty liver disease, which is associated with oxidative stress and is considered the hepatic manifestation of the metabolic syndrome.
METHODS:
We reviewed the available evidence that investigated the effects of red wine on the postprandial-induced metabolic and oxidative stress in humans.
RESULTS:
After red wine consumption with meal, despite the improvement in non-enzymatic antioxidant capacity and lipoperoxidation markers, the influence of confounding factors such as uric acid should be taken into account. Both uric acid and triglycerides increases, induced by ethanol, could cause liver damage. On the other hand, further researches are required in order to understand the meaning of the induction of antioxidant enzymes by red wine and red wine polyphenols in the context of non-alcoholic fatty liver disease.
CONCLUSION:
In conclusion, inconsistent and contrasting findings exist regarding the potential benefits of red wine consumption against postprandial stress
Interference of flavonoids with fluorescent intracellular probes: methodological implications in the evaluation of the oxidative burst by flow cytometry
No full textThe evaluation of oxidative burst is particularly relevant in many pathological and subclinical conditions. Flow cytometry provides quick and accurate measures of the reactive oxygen species production by leukocytes in most situations. However, spurious results, related to probes' efflux may be observed in several instances. Many factors affect the evaluation of the oxidative burst with fluorescent probes that require intracellular deacetylation and could be substrate of the multidrug resistance proteins (MDR). After discussing the implications of the efflux of fluorophores in the normalization strategies in flow cytometry assays, we have pointed out the possible interference of flavonoids with fluorescet probes' staining and signal. We have also reviewed the results from human intervention studies regarding the evaluation of oxidative burst with these probes. In vitro, at concentrations close to post-ingestion circulating levels, some flavonoids and their metabolites could interfere with probes' staining and fluorescence signal through different mechanisms, such as the inhibition of esterases, the modulation of the MDR-mediate efflux of probe and the inhibition of the oxidation of probe. These effects may explain the contrasting results obtained by human intervention studies. Finally, also inflammatory state or the use of drugs substrate of MDR proteins could affect the evaluation of the oxidative burst with intracellular probes
The peroxidation of leukocytes index ratio reveals the prooxidant effect of green tea extract
Full text linkDespite tea increased plasma nonenzymatic antioxidant capacity, the European Food Safety Administration (EFSA) denied claims related to tea and its protection from oxidative damage. Furthermore, the Supplement Information Expert Committee (DSI EC) expressed some doubts on the safety of green tea extract (GTE). We performed a pilot study in order to evaluate the effect of a single dose of two capsules of a GTE supplement (200mg x 2) on the peroxidation of leukocytes index ratio (PLIR) in relation to uric acid (UA) and ferric reducing antioxidant potential (FRAP), as well as the sample size to reach statistical significance. GTE induced a prooxidant effect on leukocytes, whereas FRAP did not change, in agreement with the EFSA and the DSI EC conclusions. Besides, our results confirm the primary role of UA in the antioxidant defences. The ratio based calculation of the PLIR reduced the sample size to reach statistical significance, compared to the resistance to an exogenous oxidative stress and to the functional capacity of oxidative burst. Therefore, PLIR could be a sensitive marker of redox status
Relationship between the peroxidation of leukocytes index ratio and the improvement of postprandial metabolic stress by a functional food
Full text linkFor the first time, we investigated the relationship between postprandial dysmetabolism and the Peroxidation of Leukocytes Index Ratio (PLIR), a test that measures the resistance of leukocytes to exogenous oxidative stress and their functional capacity of oxidative burst upon activation. Following a blind, placebo controlled, randomized, crossover design, ten healthy subjects ingested, in two different occasions, a high fat and high carbohydrates meal with Snello cookie (HFHCM-S) or with control cookies (HFHCM-C). Snello cookie, a functional food covered by dark chocolate and containing glucomannan, inulin, fructooligosaccharides, and Bacillus coagulans strain GanedenBC30, significantly improved postprandial metabolic stress (insulin, glucose, and triglycerides) and reduced the postprandial increase of uric acid. HFHCM-S improved PLIR of lymphocytes, but not of monocytes and granulocytes. Both meals increased granulocytes' count and reduced the lipoperoxidation induced by both exogenous free radicals and reactive oxygen species (ROS) produced by oxidative burst. Our results suggest that the healthy status of the subjects could be a limitation of this pilot study for PLIR evaluation on cells that produce ROS by oxidative burst. In conclusion, the relationship between PLIR and postprandial dysmetabolism requires further investigation
Relationship between the peroxidation of leukocytes index ratio and a functional mathematical index including uric acid levels and health-related habits: a pilot study
No full textRelationship between the peroxidation of leukocytes index ratio and a functional mathematical index including uric acid levels and health-related habits: a pilot stud
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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