Effects of chemical stress and food limitation on the energy reserves and growth of turbot, Scophthalmus maximus.

The objective of the present study is to examine the growth and energetic performance of juvenile turbot after exposure to contaminated sediment and during the subsequent recovery period with or without food limitation. We designed a two-step experiment by first exposing juvenile turbot to harbour sediment for 26 days and then transferring them to clean sea water with different frequencies of feeding for 35 days. Without food limitation, fish previously exposed to contaminated sediment compensated for weight, length and lipid reserve losses; we did not record any differences in size, Fulton's K condition index and triacylglycerol/sterol (TAG/ST) ratio after the 35-day depuration period compared to the reference fish. This result could be related to the compensatory growth mechanism observed in a wide range of fish species following a period of growth depression. With food limitation during the 35-day depuration period, recovery growth was not sufficient to restore length and weight values similar to the reference fish. Moreover, turbot previously exposed to contaminated sediment and subsequently fed twice or once a week exhibited extremely low TAG/ST ratios, but the reference fish submitted to the same restrictive feeding conditions did not. This study indicates that juvenile fish affected by chemical pollution can improve their biological performance if pollution events are followed by a period of abundant food. However, if pollution events occur during periods of food scarcity, e.g. in winter, storage of energy reserves will be compromised.

Workplace-specific challenges as a contribution to the diagnosis of occupational asthma.

The diagnosis of occupational asthma can be made by exposing workers to the relevant agent either in a hospital laboratory through specific inhalation challenges (SICs) or in the workplace. As suggested by several authors, workers with negative laboratory SIC can be monitored at the workplace under supervision. The present study aims to assess the frequency of, and identify factors associated with, a positive workplace reaction in workers with negative SIC in the laboratory. The results of workplace challenges were examined in 99 workers who underwent negative SIC between 1994 and 2004. A positive reaction either in the SIC or in the workplace was defined as a sustained fall in forced expiratory volume in one second of > or =20%. In total, 22 (22.2%) workers showed positive responses at the workplace. These subjects more often had increased baseline methacholine responsiveness (90.5 versus 67.6%). They also underwent more days of SIC testing (4.9 versus 3.3 days) and were exposed more often to two or more agents (56 versus 28.4%) and for a longer period of time (363.3 versus 220.4 min) in the laboratory. The present study illustrates the usefulness of workplace monitoring of airway function in the investigation of occupational asthma and identifies factors that are more often associated with a positive reaction.

5,10-methylenetetrahydrofolate reductase common mutations, folate status and plasma homocysteine in healthy French adults of the Supplementation en Vitamines et Mineraux Antioxydants (SU.VI.MAX) cohort.

The 677cytosine mutation identified in the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene has been frequently associated with an elevated plasma homocysteine concentration. The aim of the present study was to determine the impact of this MTHFR common mutation on plasma and erythrocyte folate (RCF) and plasma total homocysteine (tHcy) concentrations in healthy French adults. A cohort of 291 subjects living in the Paris area and participating in the Supplementation en Vitamines et Mineraux Antioxydants (SU.VI.MAX) study were analysed to assess the impact of MTHFR polymorphism 677C-->T on folate status and plasma tHcy concentration. The frequency of the mutant homozygote for 677C-->T polymorphism (677TT genotype) in the present cohort was 16.8%. There were significant differences in plasma tHcy between 677CC, 677CT and 677TT genotype groups. The RCF concentrations were significantly different between each genotype, the lowest levels being associated with the 677TT genotype. When segregated by gender, no differences in tHcy between homozygous 677TT, heterozygous 677CT and wild-type 677CC genotype groups in women were observed. The fasting tHcy in women was unrelated to the 677C-->T mutation. However, tHcy was significantly increased in men with the homozygous 677TT genotype. We also analysed the possible implication of a second new MTHFR polymorphism (1298A-->C) in subjects with mild hyperhomocysteinaemia (4th quartile of homocysteinaemia; tHcy >11.1 micromol/l). The polymorphism 1298A-->C did not have a notable effect on tHcy or on the RCF levels. Our observations confirm a relatively high frequency of the 677TT genotype in the French population. Women with this genotype did not show the same increase in tHcy observed in men. In the present study dietary folate intake was not measured. Thus, the interaction of dietary folate with the MTHFR genotype in the French population needs further study.