Search results for " method"

Oral administration of vitamin C decreases muscle mitochondrial biogenesis and hampers training-induced adaptations in endurance performance

2008

Background Exercise practitioners often take vitamin C supplements because intense muscular contractile activity can result in oxidative stress, as indicated by altered muscle and blood glutathione concentrations and increases in protein, DNA, and lipid peroxidation. There is, however, considerable debate regarding the beneficial health effects of vitamin C supplementation. Objective This study was designed to study the effect of vitamin C on training efficiency in rats and in humans. Design The human study was double-blind and randomized. Fourteen men (27-36 y old) were trained for 8 wk. Five of the men were supplemented daily with an oral dose of 1 g vitamin C. In the animal study, 24 mal…

Vitamin and Mineral Supplementation and Neuromuscular Recovery after a Running Race

2006

International audience; Purpose: This double-blind study investigated the effects of vitamin and mineral complex supplementation on the neuromuscular function of the knee-extensor muscles after a prolonged trail running race. Methods: Twenty-two well-trained endurance runners took either placebo (Pl group) or vitamins and minerals (Vm group) for 21 d before the race and for 2 d after the race. Maximal voluntary contractions (MVC) and surface EMG activity of the vastus lateralis (VL) muscle were recorded before (pre) and 1 h (post), 24 h (post 24) and 48 h (post 48) after the race. Central activation ratio (CAR), neural (M-wave), and contractile (muscular twitch) properties of the quadriceps…

Improved method for quantitative analysis of vitamin K1i and vitamin K1 2,3-epoxide in human plasma by electron-capture gas-liquid capillary chromato…

1984

A Comprehensive Review on Lipid Oxidation in Meat and Meat Products.

2019

Meat and meat products are a fundamental part of the human diet. The protein and vitamin content, as well as essential fatty acids, gives them an appropriate composition to complete the nutritional requirements. However, meat constituents are susceptible to degradation processes. Among them, the most important, after microbial deterioration, are oxidative processes, which affect lipids, pigments, proteins and vitamins. During these reactions a sensory degradation of the product occurs, causing consumer rejection. In addition, there is a nutritional loss that leads to the formation of toxic substances, so the control of oxidative processes is of vital importance for the meat industry. Noneth…

A simple high-performance liquid chromatography (HPLC) method for the measurement of pyridoxal-5-phosphate and 4-pyridoxic acid in human plasma.

2014

Abstract Background Low concentration of plasma pyridoxal-5-phosphate (PLP) is associated with hyperhomocysteinemia and inflammation. Most methods for the measurement of plasma PLP require large specimen volume and involve the use of toxic reagents. Methods We have developed a HPLC method for the measurement of PLP and 4-pyridoxic acid (4-PA) in plasma, which requires small specimen volume. The samples are prepared without adding any toxic reagents. Furthermore, we have examined whether intake of vitamin B 6 affects the concentration of plasma PLP and 4-PA. Results The coefficient of variation of the method was 6% and the recovery of the added vitamin in plasma was about 100%. The concentra…

Purification and structural characterisation of lipid transfer protein from red wine and grapes

2012

Lipid transfer proteins (LTP) play a major role in plant defence and are of particular interest due to their known ability to cause allergic reactions. These proteins are expressed in grapes and also remain detectable after vinification, especially in red wine. However, it remains unknown whether the protein undergoes any changes during the vinification process. Here, we present a purification method for LTPs from Dornfelder grapes and wine. By liquid-chromatography-mass spectroscopy (LC-MS/MS) we identified LTPs from two different species (Vitis vinifera and Vitis aestivalis). Additionally, the purified LTPs were characterised using spectrometric methods, confirming their high purity and s…

Maux de l'économie, mots des économistes

1990

International audience; La méthodologie économique a largement séparé les discours (hypthèses, théorie, corps de pensée) de l'action (représentée essentiellement par les applications ou les descriptions monographiques). Dans cet essai, avec la plus large prudence répondant à une démarche balbutiante, nous tentons de donner des représentations synthétiques, sur longue période, de l'évolution de la littérature économique ; ceci au moyen des méthodes usuelles de l'analyse des données. Il reste, quelque soit les résultats auxquels nous parvenons, que ce type de traintement repose sur l'hypothèse d'avoir pris en compte chaque production de littérature comme un objet statistique simple. L'applica…

Effects of Two Instructional Procedures on Spanish University Students’ Comprehension Monitoring when Reading Science Texts in English

2015

Abstract Two instructional approaches on comprehension monitoring in English as FL are contrasted. Although using the same materials (elementary science texts), one of them is based on tasks focusing on vocabulary and grammar, and the other one is based on main ideas identification and textual coherence. The English proficiency level was controlled and comprehension monitoring measures were obtained in the pretest and the posttest using embedded micro and macro-structural inconsistencies in texts. Results showed that teaching students to read in order to understand main ideas and to elaborate the text macrostructure produce better results than focusing attention on discourse low-level compo…

Test fairness: a DIF analysis of an L2 vocabulary test

2000

The purpose of this study is to analyse gender-uniform differential item functioning (DIF) in a second language (L2) vocabulary test with the tools of item response theory (the separate calibration t-method) and to study potential gender impact on the test performance measured by different item composites. The results of the study show that despite the fact that there are test items with indications of DIF in favour of either females or males, the test as a whole is not gender-biased. In spite of this, it was demonstrated that some item composites are gender-biased. In view of item bank building and use, it means that some of the tests constructed on the basis of an item bank might be bias…

Vocational education approach: New TEL settings—new prospects for teachers' instructional activities?

2013

This study focuses on vocational education teachers’ instructional activities in a new technology-enhanced learning (TEL) setting. A content analysis is applied to investigate teachers’ and students’ interactions in a 3D game context. The findings illustrate that when teachers’ and students’ interactions are mediated by a game, teachers seem to apply different discussion activities to empower vocational learning than they do in traditional classroom settings. Additionally, the present study shows that teachers spontaneously develop new ways of supporting vocational learning processes. In more detail, two main types of instructional activities were identified: a “knowledge-providing” approac…