The global warming potential of methane(CH_4) is about 30 times stronger than that of carbon dioxide(CO2) over a century timescale. Methane emission is hypothesized to have contributed to global climate change events ...The global warming potential of methane(CH_4) is about 30 times stronger than that of carbon dioxide(CO2) over a century timescale. Methane emission is hypothesized to have contributed to global climate change events and mass extinctions during Earth's history. Therefore, the study of CH_4 production processes is critically important to the understanding of global climate change. It has been a dogma that biogenic CH_4 detectable in the oceans originates exclusively from the anaerobic metabolic activity of methanogenic archaea in hypoxic and anoxic environments, despite reports that many oxic surface and near-surface waters of the world's oceans are CH_4-supersaturated, thereby rendering net sea-to-air emissions of CH_4. The phenomenon of CH_4 production in oxic marine waters is referred to as the "ocean methane paradox". Although still not totally resolved, recent studies have generated several hypotheses regarding the sources of CH_4 production in oxic seawater. This review will summarize our current understanding of the importance of CH_4 in the global climate and analyze the biological processes and their underpinning mechanisms that lead to the production of CH_4 in oxic seawater environments. We will also tentatively explore the relationships of these microbial metabolic processes with global changes in climate and environment.展开更多
Background: Arterial calcification is a predictive marker in patient on hemodialysis (HD), but the relationship between arterial calcification and calciprotein particles (CPPs) is unclear. Methods: We examined the eff...Background: Arterial calcification is a predictive marker in patient on hemodialysis (HD), but the relationship between arterial calcification and calciprotein particles (CPPs) is unclear. Methods: We examined the effects of ferric citrate hydrate (JTT-751) on CPP level and evaluated changes in aortic arch calcification (AoAC) grade in patients on maintenance HD (MHD). In total, 70 MHD patients were enrolled in the study and followed for 24 months. We measured serum CPP levels and fibroblast growth factor 23 (FGF 23) among propensity score-matched MHD patients. One group (n = 35) was treated with CaCO3 and the other (n = 35) was treated with ferric citrate hydrate (JTT-751). AoAC was assessed on chest-X rays. Eligible patients continued the same treatment. Results: All 70 patients completed the study. Serum CPP levels reduced in the JTT-751 group, but were not significantly different in the CaCO3 group. Among patients whose baseline AoAC score (AoACS) was ≤ 4 (median), median AoACS increased from 0 (0 - 3) to 3 (2 - 4) (p 3 group, median AoACS increased from 2 (0 - 2) to 3 (0 - 4) (p Conclusion: These results indicate that the administration of JTT-751 decreased serum CPP levels but did not inhibit AoAC progression in patients on MHD.展开更多
基金supported by the National Key Research and Development Program of China (Grant No. 2016YFA0601303)the Chinese State Oceanic Administration (SOA) (Grant No. GASI-03-01-02-05)+1 种基金the National Natural Science Foundation of China (Grant Nos. 41676122, 91328209 & 91428308)the China National Offshore Oil Corporation (Grant Nos. CNOOC-KJ125FZDXM00TJ0012014 & CNOOC-KJ125FZDXM00ZJ001-2014)
文摘The global warming potential of methane(CH_4) is about 30 times stronger than that of carbon dioxide(CO2) over a century timescale. Methane emission is hypothesized to have contributed to global climate change events and mass extinctions during Earth's history. Therefore, the study of CH_4 production processes is critically important to the understanding of global climate change. It has been a dogma that biogenic CH_4 detectable in the oceans originates exclusively from the anaerobic metabolic activity of methanogenic archaea in hypoxic and anoxic environments, despite reports that many oxic surface and near-surface waters of the world's oceans are CH_4-supersaturated, thereby rendering net sea-to-air emissions of CH_4. The phenomenon of CH_4 production in oxic marine waters is referred to as the "ocean methane paradox". Although still not totally resolved, recent studies have generated several hypotheses regarding the sources of CH_4 production in oxic seawater. This review will summarize our current understanding of the importance of CH_4 in the global climate and analyze the biological processes and their underpinning mechanisms that lead to the production of CH_4 in oxic seawater environments. We will also tentatively explore the relationships of these microbial metabolic processes with global changes in climate and environment.
文摘Background: Arterial calcification is a predictive marker in patient on hemodialysis (HD), but the relationship between arterial calcification and calciprotein particles (CPPs) is unclear. Methods: We examined the effects of ferric citrate hydrate (JTT-751) on CPP level and evaluated changes in aortic arch calcification (AoAC) grade in patients on maintenance HD (MHD). In total, 70 MHD patients were enrolled in the study and followed for 24 months. We measured serum CPP levels and fibroblast growth factor 23 (FGF 23) among propensity score-matched MHD patients. One group (n = 35) was treated with CaCO3 and the other (n = 35) was treated with ferric citrate hydrate (JTT-751). AoAC was assessed on chest-X rays. Eligible patients continued the same treatment. Results: All 70 patients completed the study. Serum CPP levels reduced in the JTT-751 group, but were not significantly different in the CaCO3 group. Among patients whose baseline AoAC score (AoACS) was ≤ 4 (median), median AoACS increased from 0 (0 - 3) to 3 (2 - 4) (p 3 group, median AoACS increased from 2 (0 - 2) to 3 (0 - 4) (p Conclusion: These results indicate that the administration of JTT-751 decreased serum CPP levels but did not inhibit AoAC progression in patients on MHD.
