Search

Les produits alimentaires tirés de la mer pourraient être une solution pour faire face à la demande alimentaire mondiale qui sera multipliée par deux d’ici 2050. Les fruits de mer englobent une grande variété d’organismes marins comestibles, à l’exception des poissons et des mammifères. Il s’agit des mollusques, crustacés, échinodermes et algues. Comme tout aliment, les fruits de mer peuvent comporter des dangers transmis à l’Homme par la voie alimentaire, qui ont une incidence sur la santé du consommateur. Ces dangers sont à la fois biologiques (virus, bactéries, parasites) et chimiques (toxines, allergènes, substances chimiques, microplastiques). L’exposition des populations à ces dangers par la consommation de fruits de mer s’explique notamment par leur mode de production et les habitudes de leur consommation. Tout d’abord, la qualité sanitaire des fruits de mer reflète la qualité du milieu aquatique dans lequel ils sont prélevés, qui peut être contaminé par différentes pollutions (fécales ou chimiques, chroniques ou accidentelles). Ensuite, les produits sont manipulés, souvent traités sans emploi d’additifs ou de conservateurs chimiques, et finalement distribués sans autre moyen de conservation que la réfrigération ou la congélation. Enfin, les habitudes alimentaires de ces produits favorisent l’exposition à certains dangers. La sécurité sanitaire de ces produits doit être intégrée tout au long de la chaîne alimentaire, sous la responsabilité partagée par tous les acteurs de la filière de production. La sécurité sanitaire des fruits de mer apparaît comme un enjeu de santé publique émergent de portée mondiale, car la mer ne s’arrête pas aux frontières.

This study aimed to show the intensity of efforts, swimming patterns, and technical and tactical aspects of waterbasket. In particular, during a friendly waterbasket match, ten male water polo players (age: 17±1 yrs; height: 179±9 cm; body mass: 74±15 kg) were analyzed in terms of heart rate, blood lactate, grip strength, swimming patterns (horizontal and vertical swimming with and without ball possession), and technical and tactical aspects (actions, passes, players involved, lost possessions, fouls, and occurrence, successful, and origin area of shots). Results showed differences for heart rate intensities (p<0.05), highlighting the 81-90% of maximal heart rate as the most frequent category. After the 2nd (4.2±1.6 mM) and 4th (4.6±2.2 mM) period, the lactate concentrations was higher than before the match (p<0.05). No differences has been reported for grip strength. Vertical swimming was the most frequent activity (74%) and the others did not show patterns longer than 10 s. Waterbasket match has been mainly characterized by Even actions (68%) and shots performed outside the 1.5m area, even though the reverse picture emerged for Primary Counterattack. In conclusion, this study provides a good reference for waterbasket and adjacent sports, even showing a useful model to gather information in linked competitive situations.!

Abstract: In this paper, we investigate some mathematical structures underlying the physics of linear optical passive (LOP) devices. We show, in particular, that with the class of LOP transformations on N optical modes one can associate a unitary representation of U(N) in the N-mode Fock space, representation which can be decomposed into irreducible sub-representations living in the subspaces characterized by a fixed number of photons. These (sub-)representations can be classified using the theory of representations of semi-simple Lie algebras. The remarkable case where N = 3 is studied in detail.

The role of gonadal hormones and persistent pain (formalin test) in the regulation of interferon-γ (IFN-γ) production in splenocytes was investigated in male and female rats. Animals were either sham-operated (Intact) or gonadectomized (GDX) and, 3 weeks later, were subcutaneously injected with formalin (50 μl, 10%) or only pricked with a syringe needle in the dorsal hind paw. Sixty minutes after treatment the animals were deeply anesthetized and the spleens were dissected under aseptic conditions. Blood was collected from the abdominal aorta for measurement of plasma steroids. IFN-γ production was determined in vitroin the splenocytes after Con A stimulation. Splenocytes of Intact females showed higher IFN-γ production than those of Intact males. This sex difference disappeared in GDX animals because of the lower levels in GDX females. Formalin decreased IFN-γ in both Intact and GDX groups. In females, there was a positive correlation between IFN-γ production in splenocytes and plasma estradiol levels. The present data demonstrate a sex difference in IFN-γ production (due to the immunostimulating effect of estradiol in females) and an immunodepressive role of pain in both sexes.

Endocrine and immune parameters, namely glucocorticoid receptors (GcR) and IFN-γ production in peripheral blood mononuclear cells (PBMC), and corticosterone in plasma, were studied in groups of four male rabbits observed in seminatural conditions in relation to agonistic behaviour and to seasonal variations. These parameters were selected on the basis of the findings that the presence of GcR in PBMC gives an indication of the in vivo biological effects of glucocorticoids and that PBMC cytokine production and plasma corticosterone are related to social behaviour. The frequency of active and passive behaviours was used to rank the animals. Seasonal variations were present for agonistic behaviours (Attack, Follow, Chase) and for plasma corticosterone, which were significantly higher in winter. IFN-γ production in PBMC was increased after social interactions in both seasons, while plasma corticosterone was increased only in winter. GcR capacity in PBMC was decreased after social interactions. The results indicate that social and physical environmental factors are correlated with immune-endocrine functions.

In eight top-level male endurance swimmers the aerobic performance and the response to exercise of total testosterone (T), free testosterone (fT), sex hormone binding globulin (SHBG), non-SHBG-bound testosterone (NST) and cortisol (C) were evaluated during a training season. The swimmers participated in three test sessions which occurred 6, 12 and 24 weeks after the beginning of the season. During each session, after a standard warm-up, the swimmers performed a set of 15 × 200-m freestyle, with a 20-s rest between repetitions, at a predetermined individual speed. Three blood samples were collected: before warm-up, at the end of the set, and after 1 h of recovery. A few days before each session, the individual swimming velocity associated with a 4 mmol · l-1 blood lactate concentration (?4) was assessed as a standard of aerobic performance. The values of ?4 were lower in the second session than in the third one. The concentrations of C, which increased after the exercise, showed the highest values in the second session. The values of T and the T: SHBG ratio increased after the exercise but returned to their initial concentrations during the recovery period. The values of fT and NST increased after the exercise in the first and third sessions. In the initial two sessions, when the aerobic performance was still low, the concentrations of NST decreased to below the initial values after recovery. In session III, when the adaptation to the training workload was complete, NST returned to resting concentrations after recovery. The results would suggest that stressful stimuli produced by an increase in training volume may induce changes in androgen metabolism during exercise. In this respect, NST would appear to be a better index of metabolic response than T, T/SHBG and fT.

The response of total testosterone (T), free testosterone (fT), sex hormone-binding globulin (SHBG) and non-SHBG-bound testosterone (NST) to the same exercise protocol was evaluated in two different experiments on long distance runners. The first experiment was performed in the morning at 0900 hours with nine athletes, while the second was carried out in the afternoon at 1500 hours with seven athletes. During each experiment, each athlete ran for 1 h at the previously determined speed corresponding to 2 mmol · l-1 blood lactate concentration. Three venous blood samples were collected in each experiment: before exercise, at the end of running and after 1 h of recovery. Total T and SHBG showed similar responses: in the first experiment they had decreased after exercise, while in the second they had increased at the end of running. A positive correlation between total T and SHBG concentrations was found at the end of exercise. In both experiments, NST and fT had increased after exercise and decreased to initial concentrations during recovery. The results would suggest the existence of a compensatory mechanism which maintains adequate concentrations of biologically active T when total T concentrations decrease.

It was the aim of the present experiment to detect possible effects of branched-chain amino acids (BCAA) on the endocrine response to 1 h of continuous running. Blood samples were collected from 14 long-distance runners (age 24–42 years) in two different trials performed at 1-week intervals. In both trials (E and P) blood samples were collected at the following times: 9 a.m. (basal values sample), 10.30 a.m. (sample 90), 11.30 a.m. (sample 150), 12.30 p.m. (sample 210); the athletes performed 1 h of running at a constant predetermined speed between samples 90 and 150. Following the basal sample a mixture containing BCAA (E trial), or not containing BCAA (P trial) was ingested. In both trials no hormone basal concentrations, except insulin, were changed before exercise. In P trial, following exercise (sample 150), human growth hormone (HGH), prolactin (PRL), adrenocorticotropic hormone (ACTH) and cortisol (C) increased, while testosterone (T) decreased. In sample 210, after 1 h of rest, while ACTH, PRL and HGH had recovered to basal concentrations, C remained elevated and T displayed a further decrease. In the E trial a similar pattern of change was observed in sample 150 for HGH, PRL, ACTH and C; in sample 210 HGH and PRL displayed significantly lower values than in the corresponding P trial samples. The T was not modified by the running exercise and increased during the recovery period. It is, therefore, suggested that BCAA administration before exercise affects the response of some anabolic hormones, mainly HGH and T.

The plasma hormonal response following a swimming competition in the sea (18 km) was evaluated in 12 top level male endurance swimmers. At the end of the effort, while plasma renin activity (PRA) and aldosterone concentration (ALDO) were unchanged, a significant increase in plasma atrial natriuretic peptide (ANP) and antidiuretic hormone (ADH) concentrations were recorded. These changes were associated with a decrease in haematocrit and an increase in Na+ and Cl- plasma concentrations. The individual variations of ANP (difference between the final and initial concentrations) were inversely correlated with the corresponding individual variations of PRA and ADH. The results suggest that, during prolonged swimming, ANP may exert an inhibitory effect on the PRA-ALDO axis and have a modulatory role with regard to ADH secretion.

In the toad Bufo bufo reproductive activity took place within a few weeks in early spring: males were sexually active when entering and staying in the breeding pond and did not exibit any sexual behaviour when leaving.We analyzed changes in the plasma levels of corticosterone and androgens in the toad Bufo bufo during two consecutive breeding seasons under natural conditions. Males were trapped and blood collected at their arrival and departure from the pond where reproductive behaviour occurred. Androgens decreased in animals leaving the pond in both years and the final levels were negatively correlated with the length of stay in the water. The final levels of corticosterone were also negatively correlated to the time spent in the water. A significant corticosterone decrease in animals leaving the pond was observed only in the first year, and it is probably due to sampling technique.

In 18 trained football players, blood samples were collected before a football match, at half-time, at the end, and 45 and 90 min after the end of the match. The testosterone (T) level showed a decrease in the rest period. Dihydrotestosterone (DHT) increased during the match, but returned to initial levels in the last samples. The T/DHT ratio decreased, reached the minimal value at the end of the exercise, and returned to basal levels in the rest period. Cortisol and androstenedione levels increased during the match, but returned to control levels 45 and 90 min after the end of the match, respectively. It is suggested that during this type of exercise anabolic and catabolic hormones may be simultaneously activated.

Diffusion-controlled electrodeposition was investigated experimentally and by finite element method simulations of the concentration profile on microstructured band electrode arrays (MEA) and compared to existing theoretical approaches. The simulations revealed the establishment of a diffusion layer significantly larger than anticipated according to existing models for individual bands. The electrochemical depositions were simulated by extending the finite element method to allow the modeling of changing electrode geometries during growth by use of automated remeshing steps. As an ideal case of electroplating, thin films of copper electrodeposited onto MEA of gold on SiO2/Si wafers were studied as a benchmark system. The electrodeposition of ZnO on MEA following initial reduction of O2served as an example of a multi-step reaction. The simulations considered an increasing depletion of the reactant (O2in the case of ZnO, Cu2+in the case of Cu) toward the electrode bands and film growth limited by mass transport. The growth of experimentally observed dendrites and even their detailed size distribution over the whole array was precisely predicted by the simulations. An extended understanding of diffusion-controlled growth could be achieved and used to study the temporal development of electrochemical depositions, applicable also in complex geometries.

SINCE its first isolation by Laqueur et al.1in 1935 from tissue of steer testis, testosterone has been obtained from some species of mammals only, namely, horse and man, by Ruzicka et al.2,3. Furthermore, Brady4, by in vitro experiments on the biosynthesis of testosterone from 14C-acetate, indicated that testosterone is probably the androgenic testicular hormone in two additional species, rabbit and hog. Androgenic substances of non-mammalian vertebrates are still unknown. On the other hand, œstradiol-17β has been found to be the œstrogenic hormone not only in mammals but also in the elasmobranch Squalus suckleyi5, in the lungfish Protopterus annectens6, in birds7and in the starfish Pisaster ochraceus8. The investigation of the androgenic material in non-mammalian vertebrates seems therefore necessary to fill this gap, and is of obvious evolutionary importance.

Interdigitated microstructured electrode arrays of gold or silver bands were used as substrates for the electrodeposition of crystalline ZnO thin films under pulsed galvanostatic conditions from aqueous Zn(NO3)2solutions. For current densities below the limiting current density, homogenous films of ZnO were obtained as proven by scanning electron and confocal laser microscopy. For current densities greater than those limited by the diffusion of Zn2+and NO3−, strongly dendritic structures were formed. Film growth was analyzed based on the duplex diffusion layer model. The influence of convective diffusion was directly observed when only one set of electrode bands was polarized during deposition. By use of an underlying gate electrode in the substrate, field-effect measurements were performed to electrically characterize the samples.

RESULTS of biological assays have shown Conger conger ovary1as well as other teleost ovaries2–6to contain œstrogenic material. No indication of the chemical structure of the steroids present in the ovaries of these fishes has so far been ascertained. Only recently œstradiol-17β has been identified in the ovarian extracts of Salmo irideus and œstradiol-17β, œstriol and 16-epi-œstriol in the ovarian extracts of Cyprinus carpio7.