Quantum chemical calculation to elucidate the biodegradation pathway of methylphenanthrene by green microalgae.

Alkylated polycyclic aromatic hydrocarbons (APAHs) are the main components of polycyclic aromatic hydrocarbons (PAHs) in petroleum-contaminated waters. In our study, three kinds of green microalgae (Pseudokirchneriella subcapitata, Chlorella vulgaris and Scenedesmus obliquus) were shown to degrade six kinds of methylphenanthrenes (1-methylphenanthren, 2-methylphenanthrenem, 3-nmmethylphenanthrene, 4-methylphenanthren, 9-methylphenanthrene and 3,6-dimethylphenanthrene) with different degrading abilities. Among the six methylphenanthrenes, 99.8% of 1-methylphenanthrene (1-MP) was removed and 75.6% of 3,6-dimethylphenanthrene (3,6-DMP) was removed by P. subcapitata after 7 days of incubation. The metabolites of 1-MP and 3,6-DMP were identified by gas chromatograph-mass spectrometer (GC-MS). Six metabolites of 1-MP and one metabolite of 3,6-DMP were found, they were all monohydroxylated methylphenanthrenes. The -OH group was added to either methyl-group or benzene ring through the monooxygenase system, and the methyl-group attack was the main pathway. This research increases our knowledge of the degrading ability of APAHs by green microalgae and offers information for the bioremediation of APAHs. Quantum chemical calculation was conducted to elucidate the biodegradation metabolites of methylphenanthrene by green microalgae, which is a helpful tool in the bioremediation of environmental pollution.

Bone Mineral Density in Patients With Rheumatoid Arthritis and 4-Year Follow-up Results.

BACKGROUND: Osteoporosis is a common complication in patients with rheumatoid arthritis (RA). The change of bone mineral density (BMD) in patients with RA is slow, and little data are known about the long-term change of BMD. OBJECTIVES: This study aimed to determine the frequency of osteoporosis and the long-term change on BMD in a cohort of Chinese patients with RA routinely receiving calcium and vitamin D supplementation. METHODS: A total of 304 consecutive patients with RA were recruited. Bone mineral density measurements of the forearm, lumbar spine, and total hip were performed by dual-energy x-ray absorptiometry and compared with 200 age- and sex-matched healthy controls. Risk factors were analyzed by logistic regression models. RESULTS: The prevalence of osteoporosis at all measured sites in patients with RA was statistically significantly higher than in healthy controls. A total of 107 patients of the cohort had a mean of 4 years of follow-up. More patients with BMD decrease were found without calcium and vitamin D use compared with those who continuously took calcium and vitamin D (64.3% vs 19.8% at the forearm and 28.6% vs 16.1% at the total hip, respectively). Only the use of calcium and vitamin D supplementation was associated with a decreased risk of BMD decrease both at the forearm and at the total hip. CONCLUSIONS: Osteoporosis is common in Chinese patients with RA. Routine use of calcium and vitamin D supplementation decreased the risk of BMD decrease and should be recommended for all patients with RA.