Risk Factors for Postoperative Permanent Neurological Dysfunction After Stanford Type A Aortic Dissection: A Systematic Review and Meta-Analysis of 11382 Cases.

OBJECTIVE: To systematically evaluate the risk factors for permanent neurological dysfunction (PND) after Stanford type A aortic dissection (TAAD). METHOD: Electronic databases included PubMed, Embase, Web of Science, CNKI, WanFang Data, VIP, and CBM. We collected studies about risk factors for PND after TAAD was published from inception to December 2021. Two authors independently assessed the quality of the studies, and a meta-analysis was performed by RevMan 5.3 Software. RESULTS: A total of 20 studies involved 11382 cases, and among them, 1321 patients suffered PND, including 34 predictive risk factors. The meta-analysis showed that age (OR=1.11, 95% CI (1.06, 1.16), P < 0.0001), preoperative PND (OR=2.95, 95% CI (2.14, 4.07), P < 0.00001), retrograde tear in the ascending aorta (OR=6.67, 95% CI (3.23, 13.79), P < 0.00001) were independent risk factors for PND after TAAD surgery. CONCLUSIONS: Current evidence shows that age, preoperative PND, retrograde tearing in the ascending aorta are risk factors for PND after TAAD. These factors can be used to identify high-risk patients, providing guidance for medical staff to develop perioperative preventive strategies to reduce the incidence of PND. The results should be validated by higher-quality studies.

[Role of Sulfate-Reducing Bacteria in Mercury Methylation in Soil of the Water-Level-Fluctuating Zone of the Three Gorges Reservoir Area].

Soil simulation experiments with or without addition of external mercury and a non-indigenous bacterium were conducted under laboratory conditions, in order to investigate whether sulfate-reducing bacteria (SRB) are the dominant mercury methylators in the water level fluctuation zone (WLFZ) of the Three Gorges Reservoir, which is a typical periodical wet and dry alternating environment, locating in the Shibaozai Xinzhen Village, Zhong County, Chongqing, China (E108°12'3″ and N30°24'36″). The original soil from the WLFZ was firstly sterilized and then inoculated with or without Desulfovibrio africanus (D. africanus DSM-2603, commercially purchased from the Culture Preservation Center of Microorganisms in Germany, DSMZ) as the control (Test A). The sterilized soils were respectively mixed with 0, 1, or 5 mg·kg-1 Hg2+ soil under submerged and non-submerged conditions to simulate changes in the concentrations of total mercury, methylmercury and the growth of D. africanus, and the effects of environmental factor on such changes. The results showed that under the submerged situation the release of total mercury (THg) from soils (Test B) increased with the increase of external Hg2+ addition, and the higher the external Hg2+, the quicker the Hg2+ release was. Meanwhile, D. africanusdisplayed an ecological adaptability to mercury and its colony numbers were significantly correlated with the MeHg concentrations in the soil. In soil with 5 mg·kg-1 of external Hg2+, the total number of D. africanus reached the highest (3.65×104 cfu·g-1) while the highest MeHg concentration was 7.60×104 ng·kg-1. However, on the one hand, the averaged numbers of soil SRB in the test B was only 193 cfu·g-1. On the other hand, in soil with 5 mg·kg-1of external Hg2+, the MeHg concentration was as low as 5.54×103 ng·kg-1, while no significant relationships were observed between SRB and MeHg. As a result, our results indicated that SRB was not a predominant mercury methylator, while other bacterial groups, either aerobic or anaerobic bacteria, might play an important role in mercury methylation in the WLFZ of the Three Gorges Reservoir, China.

[Identification of a Facultative Bacterium Strain with the Ability to Methylate Mercury Under Both Aerobic and Anaerobic Conditions].

A strain with the ability to methylate mercury under both the aerobic and anaerobic conditions was isolated from soil of the water-level-fluctuation-zone in the Three Gorge Reservoir in Shibaozhai Village, Zhongxian Country, Chongqing, China (E108°12'3″ and N30°24'36″). The soil was classified as Purple soil with a pH of 7.97 (0-20 cm depth). The isolation was performed under 1.0 mg·L-1 HgCl2 conditions. After its morphological and physiological characterization, and its phylogenetic analysis using 16S rDNA gene sequence, the strain was identified as Pseudomonas fluorescens sp., and named as Pseudomonas fluorescens XD-MeHg-B2 (GenBank accession number: KU954349). On one hand, at 30℃ under aerobic condition, the concentration of methylmercury (MeHg) in the PBS (phosphate buffer saline) solution, which was inoculated with 1×1011 cfu·mL-1 suspension of P. fluorescens XD-MeHg-B2 and an initial Hg2+ of 200 ng·L-1, was exponentially increased to 1.22 ng·L-1±0.15 ng·L-1 after 60 min incubation and then approached to the maximum of 3.85 ng·L-1±0.33 ng·L-1 160 min after incubation. The largest mercury methylation rate was 1.93%. On the other hand, at 30℃ under anaerobic condition, the concentration of MeHg in the PBS solution, which was also inoculated with 1×1011 cfu·mL-1 suspension of P. fluorescens XD-MeHg-B2 and an initial Hg2+ of 200 ng·L-1, was 2.86 ng·L-1±0.73 ng·L-1 and the largest mercury methylation rate was 1.43% 180 min after incubation. As a result, P. fluorescens XD-MeHg-B2 showed its ability to methylate mercury under both aerobic and anaerobic conditions while with a comparatively hysteretic and lower ability of mercury methylation. These results demonstrated that P. fluorescens XD-MeHg-B2 could be a promising candidate for further studies on mercury biogeochemical cycle, particularly under dry-wet alternative conditions.