Role of the rhizosphere of a flooding-tolerant herb in promoting mercury methylation in water-level fluctuation zones.

The water-level fluctuation zone (WLFZ) has been considered as a hotspot for mercury (Hg) methylation. Flooding-tolerant herbs are gradually acclimated to this water-land ecotone, tending to form substantial root systems for improving erosion resistance. Accompanying rhizosphere microzone plays crucial but unclear roles in methylmercury (MeHg) formation in the WLFZ. Thus, we conducted this study in the WLFZ of the Three Gorges Reservoir, to explore effects of the rhizosphere of a dominant flooding-tolerant herb (bermudagrass) on MeHg production. The elevated Hg and MeHg in rhizosphere soils suggest that the rhizosphere environment provides favorable conditions for Hg accumulation and methylation. The increased bioavailable Hg and microbial activity in the rhizosphere probably serve as important factors driving MeHg formation in the presence of bermudagrass. Simultaneously, the rhizosphere environments changed the richness, diversity, and distribution of hgcA-containing microorganisms. Here, a typical iron-reducing bacterium (Geobacteraceae) has been screened, however, the majority of hgcA genes detected in rhizosphere, near-, and non-rhizosphere soils of the WLFZ were unclassified. Collectively, these results provide new insights into the elevated MeHg production as related to microbial processes in the rhizosphere of perennial herbs in the WLFZ, with general implications for Hg cycling in other ecosystems with water-level fluctuations.

Efficacy and safety of oral compared with intravenous tranexamic acid in reducing blood loss after primary total knee and hip arthroplasty: a meta-analysis.

BACKGROUND: Tranexamic acid (TXA) is an anti-fibrinolytic agent successfully preventing blood loss when using intravenously (IV) in total hip arthroplasty (THA) and total knee arthroplasty (TKA). An oral administration, which is available on blood sparing, has been reported exhibit profound cost-saving benefits. The aim of this meta-analysis is to investigate whether the administration of oral and intravenous tranexamic acid postoperatively has equivalent blood-sparing properties in these patients. METHODS: The online electronic databases were searched for eligible literatures updated on September 2018. Studies assessing the effect between oral TXA and intravenous TXA (IV-TXA) in those undergoing TKA or THA were included. All the data were pooled with the corresponding 95% confidence interval (CI) using RevMan software. Based on the heterogeneity, we performed a systematic analysis to explore the overall results across the included studies. RESULTS: Nine studies met our inclusion criteria. No significant differences were identified with regard to the Hb drop (SMD = - 0.03,95%CI = - 0.18-0.12, P = 0.67), total Hb loss (SMD = 0.10,95%CI = - 0.06-0.26, P = 0.24), total blood loss (SMD = - 0.00,95%CI = - 0.20-0.20, P = 1.00), transfusion rate (OR = 0.77,95%CI = 0.54-1.10, P = 0.14), DVT rate (OR = 0.58,95%CI = 0.19-1.75, P = 0.33), and length of hospital stay (SMD = - 0.05,95%CI = - 0.28-0.17, P = 0.63) between the oral groups and intravenous group. CONCLUSION: The blood-sparing efficacy of oral TXA is similar to that of the intravenous forms in the setting of THA and TKA. Considering the cost-benefit superiority and ease of administration of oral TXA, further studies and clinical trials are required to further identify the optimal administration for THA and TKA.