Digestive solubilization of Cd in highly-contaminated sediment by marine deposit feeders: The roles of intestinal surfactants in Cd mobilization and Re-Adsorption processes.

Marine deposit feeders are of ecological significance in transferring sedimentary Cd along aquatic food chains. A key process for this transfer is these organisms' dietary uptake of Cd via solubilization of Cd present in ingested contaminated sediment. To better understand the bioavailability of sedimentary Cd to deposit feeders, the present study used in vitro extraction experiments to explore the contribution of different digestive agents (proteins, amino acids and surfactants) to the solubilization of Cd from sediment collected in a highly-contaminated Chinese bay. This was done for various commercially-available mimetic digestive agents (the protein BSA, a mixture of amino acids, and the surfactants rhamnolipid and SDS), and for proteins and surfactants collected from the gut juice of a sipunculan worm. The Cd mobilization capacity of BSA was significantly higher than that of the amino acids and the commercial surfactants. In the presence of BSA, > 70% of the released Cd became associated with this protein. In contrast, the digestive proteins from the sipunculan had a lower Cd mobilization capacity than was the case for the other digestive agents and the majority of the released Cd (∼80%) was associated with small molecular weight fractions. The differences in Cd mobilization between the BSA and the digestive proteins were attributed to differences in their sediment-adsorption tendencies and their Cd-complexing capacities. While the digestive surfactants had minor effects on the release of sedimentary Cd, they significantly enhanced Cd mobilization by the digestive proteins when both were present simultaneously. Our results suggest that the characteristics of proteins should be considered when using commercially-available mimetic digestive agents to explore Cd bioavailability in sediments. Furthermore, digestive surfactants seem to have important effects on the solubilization of Cd during gut passage by reducing the adsorption of the digestive proteins to the sediments.

[A study of the prevalence of obstructive sleep apnea hypopnea syndrome in drivers].

OBJECTIVE: To study the prevalence of snoring and obstructive sleep apnea hypopnea syndrome (OSAHS) in drivers in Chengde city. METHODS: The prevalence of snoring and OSAHS in drivers was investigated by a questionnaire, and some of the drivers with more severe snoring were also evaluated by polysomnographic study. RESULTS: Among the 718 investigated drivers, never snoring was reported in 68.3% (490/718), mild snoring in 31.7% (228/718), and moderate and severe snoring in 16.6% (119/718). The prevalence of snoring increased with age. The prevalence of snoring was higher in males (33.6%) than in females (15.3%). When their knowledge of snoring was evaluated, 43.2% (310/718) thought snoring was not a disease, 16.7% (120/718) considered snoring as a disease but needed no treatment, 40.1% (228/718) considered it as a disease and needed treatment but only 1 had ever received treatment. If AHI > or = 5/h was used as the diagnostic criteria, the prevalence of OSAHS in the drivers was 12.3% (28/228); and if Epworth Sleepiness Scoring (ESS > or = 9) was combined, the prevalence of OSAHS was 4.1% (9/228). CONCLUSION: The prevalence of snoring in drivers was 31.7%, and the prevalence of OSAHS was 4.1%. Drivers need to be informed of the potential harm of OSAHS on their work.