In this article, an internationally renowned pulmonologist with extensive experience in teaching and publishing gives practical advice to young physicians and/or residents on the importance of doing research, the steps for planning a project and also some do's and don’ts of writing and publishing a scientific paper.En este artículo, un neumólogo internacionalmente reconocido, con amplia experiencia académica e investigadora, da consejos prácticos a residentes y médicos jóvenes para llevar a cabo proyectos de investigación y publicaciones científicas.

We examined the effects of weight loss induced by restricting energy and fluid intake on antioxidant status and oxidative stress of judo athletes. Twenty male judoka were randomly assigned to one of two groups (Group A: called diet, n = 10; height 174.8 +/- 1.9 cm, body weight 75.9 +/- 3.1 kg; they were asked to lose approximately 5 % of their body weight through self-determined means during the week before the competition; Group B: called control, n = 10; height 176.4 +/- 1.1 cm, body weight 73.3 +/- 6.3 kg maintained their body weight during the week before the competition). A battery of tests was performed during a baseline period (T1) on the morning of a simulated competition (T2) and 10 minutes after the end of the competition (T3). These tests included assessment for body composition, determination of lag phase (Lp) before free radical induced oxidation, maximum rate of oxidation (Rmax) during the propagating chain reaction and maximum amount of conjugated dienes (CDmax) accumulated after the propagation phase, and lipidic profile. Uric acid concentrations were also evaluated in plasma. Dietary data were collected using a 7-day diet record. We noted that the athletes followed a low carbohydrate diet whatever the period of the investigation. Concerning antioxidant nutrients, we can notice that mean nutritional intakes are in the normal range values for vitamin A, C and E at T1 and T2. Rapid weight loss induced a significant increase in Lp values (p < 0.05) and uric acid concentrations without alterations in oxidative stress. Our data also showed that the competition induced the same changes of oxidative-antioxidant status whatever the dietary intake during the seven days before the competition. Moreover, the effect of the competition on the antioxidant and oxidant parameters was more pronounced than the diet. Theses results could be linked to the food containing a large proportion of PUFA and a relative low proportion of carbohydrates.

Bovine meat is criticised for the bad nutritional image of its lipids and fatty acids. However, with dairy products, beef is the major source of conjugated linoleic acid (CLA) which could have several human health benefits. The present study compared, from data of five nutritional experiments on bovine animals performed by the laboratory, the impact of factors linked to the animals (breed, age, sex, type of muscle) and to feeding conditions (basal diet, lipid supplements) on the CLA proportion and composition in muscles. Among these factors, linseed supplementation was an efficient way to increase CLA proportion in beef (+22% to +36%) but was highly modulated by the nature of the basal diet, and by intrinsic factors (breed, age/sex, type of muscle) since these ones could modulate CLA proportion in beef from 24% to 47%. Moreover, these factors modified also the proportion of cis,trans-CLA, related to cis,cis- and trans,trans-isomers. Specific biological properties of these latter isomers should be determine to understand the consequences of intramuscular CLA isomer variations for the health of consumers.

Physical training is known to increase the antioxidant defence system and reduce exercise-induced oxidative stress. However, intense physical aerobic and anaerobic training and competition such as those imposed on professional rugby players, can induce an increase of oxidative stress which can be implicated with the arrival of overtraining. The aim of this study was to test the effect of training and competition load on oxidative stress, antioxidant status, haematological, and cell damage markers in high-level rugby players during a competitive season. Blood samples were collected four times in one year. Oxidative stress (R-max), antioxidant (vitamin E, uric acid, TAC, and lag phase), haematological (neutrophils and monocytes) and biochemical (CK and myoglobin) parameters, as well as training and competition load, and competition results were measured. Intense periods of training and competition (T1 and T4) induced a significant higher maximum rate of conjugated dienes oxidation (+67.2% in T1 and +40.6% in T4) compared to those observed at the reference time (T3). Those periods also induced an increase in uric acid (+ 6.9% and 3.2%), and inflammatory markers such as monocytes (+ 13.3 % and 10.7%). On the other hand, vitamin E (- 8.7% in T1) and lag phase (- 23.0% and - 14.7%) were lower during these periods showing a possible training-induced antioxidant down-regulation. The less intense period of training (T2) was accompanied by lower neutrophils (- 8.5%), CK (- 53.7%), and myoglobin (-16.2%) values. The results suggest that oxidative stress and antioxidant measurement are significant in the biological follow-up of athletes.

Two experiments were conducted using crossbred Salers x Charolais fattening steers fed diets enriched with no supplemental oilseeds or oils rich in either n-6 PUFA (from sunflower seeds) or n-3 PUFA (from linseeds) provided either as seeds incorporated in the diet (i.e., not protected from ruminal bacterial hydrogenation) or by chronic infusion into the duodenum (protected form). In the Sunflower experiment, animals (initial age = 454 +/- 20 d; initial BW = 528 +/- 36 kg) received a control diet for 70 d (CS, n = six) consisting of hay and concentrate, or the same basal diet supplemented with sunflower oil (4% of dietary DM), either fed as seeds (SS, n = six) or infused into the duodenum (ISO, n = six). The same experimental design was applied to animals (initial age = 412 +/- 33 d; initial BW = 536 +/- 33 kg) used in the Linseed experiment (CL, LS, and ILO; n = 8 per group). For all animals, blood was sampled every 15 d during 70 d. In both trials, a significant diet x time interaction (P < 0.001) was detected for plasma concentrations of apolipoprotein A-I, phospholipids, and free and esterified cholesterol, with values increasing with time during administration of the PUFA-rich diets being more evident with ISO and ILO diets. Plasma fatty acids were altered with oil infusions, with increased concentrations of n-6 (1.6-fold; P < 0.05) and n-3 PUFA (4.5-fold; P < 0.05) and of their respective indicies of peroxidizability (1.2- and 1.5-fold with Diets ISO and ILO, respectively; P < 0.05). In vitro copper-induced peroxidation of lipids revealed a decreased length of the lag phase in the process of conjugated diene generation by 48% (P < 0.005) with the ILO diet, indicating less resistance against peroxidation than in control steers. Compared with CS, the ISO treatment increased plasma a-tocopherol (x2.5; P < 0.05) leading to similar resistance against peroxidation. After depletion of this vitamin, the rates of peroxidation and production of conjugated dienes were greater (twofold; P < 0.05) with the ISO and ILO diets than with the others. In conclusion, infusion of sunflower or linseed oil into the duodenum altered the composition and distribution of plasma lipids and increased the plasma concentration of PUFA. The sensitivity of plasma PUFA to peroxidation depends on the plasma level of antioxidants, especially vitamin E, a nutrient important both for the health of animals and for the stability of the blood lipids until their tissue deposit.

The health value of ruminant products (milk, meat) can be improved by different dietary strategies in order to lower atherogenic fatty acids (FA) such as some saturated FA (14:0 and 16:0) and transvaccenic acid (18:1 Delta 11t) and favour beneficial polyunsaturated FA (PUFA) with a particular emphasis on n-3 PUFA. Hence, fresh grass which is rich in linolenic acid (18:3n-3) and vegetable oils (supplied as seeds or free oil) which are rich in linoleic (18:2n-6, from soybean or sunflower seed) or linolenic (from linseed) acids are the main dietary sources of PUFA which can be readily incorporated into lipids of milk or muscle tissues. Nevertheless, the high sensitivity of PUFA to lipoperoxidation in plasma and tissues of ruminants can increase the risk of alteration of the animal health in addition to a lower nutritional quality of their products. Thus, further investigations are needed to define the most efficient combination of antioxidant sources in the context of dietary PUFA supplementations in lactating and meat producing ruminants.

To meet recommended dietary allowances for humans, meat lipids of bovines should be enriched in polyunsaturated fatty acids (PUFA). The aim of this work was to determine, in fattening steers, the effects of lipid supplements from sunflower (rich in PUFA) on 1) animal performances, 2) lipids, PUFA and SFA contents of muscles Rectus abdominis (RA) and Longissimus thoracis (LT), 3) muscle lipid peroxidation level and metabolic properties, and 4) organoleptic quality traits of meat. Charolais x Salers steers (453 days-old, BW: 502 kg, n = 18), were alloted in 3 groups of 6 animals. They were given, for 70 days, a control diet composed of hay (54% diet DM) and concentrate feed (46%), or the same diet supplemented with sunflower oil (4% diet DM) incorporated in the ration as crushed seed or infused directly into the proximal duodenum ("a protected form"). Body weight gain was low (540 g/d) because of unfavourable rearing conditions, but similar for the 3 groups. Carcass yield (60%) and proportions of fat depots (14%) were not modified by lipid supplementations. However, duodenal oil infusion increased (+ 100%) significantly the C18:2n-6 (main PUFA) content of RA and LT muscles resulting in a 60% higher value of the ratio PUFA/SFA, and, a higher sensitivity of muscle lipids to peroxidation in LT muscle.Sunflower oil infusion into duodenum altered specifically the metabolism of RA (an oxido-glycolytic muscle), characterized by a simultaneous decrease in the activity of lactate dehydrogenase (enzyme of glycolytic metabolism) and increase in that of betaOH-acyl CoA dehydrogenase (enzyme of oxidative metabolism). Lipid supplementation did not modify significantly tenderness and juiciness of meat but led to an higher "metal" taste flavour in both RA and LT muscles after 2 days of maturation. This kind of flavour could result from both metabolic changes in muscle fiber activities towards an oxidative type (as noted in RA); and a higher PUFA content in the two muscles.