Thawing Rate Predicts Acute Pulmonary Vein Isolation after Second-Generation Cryoballoon Ablation

OBJECTIVE: To evaluate whether thawing rate could be a novel predictor of acute pulmonary vein isolation (PVI) and explore the predictive value of thawing rate as a factor ensuring long-term PVI (vagus reflex). METHODS: A total of 151 patients who underwent cryoballoon ablation for atrial fibrillation (AF) were enrolled in this retrospective study between January 2017 and June 2018. The thawing rate was calculated using the thawing phase of the cryoablation curve. Receiver operating characteristic (ROC) curve was used to analyze the predictive value of the thawing rate for acute PVI and vagus reflex. RESULTS: ROC curve analyses revealed that the interval thawing rate at 15o C (ITR15) was the most valuable predictor of PVI, with the highest area under curve (AUC) value of the ROC curve. The best cut-off value of ITR15 for PVI was p2.14o C/S and its sensitivity and specificity were 88.62% and 67.18%, respectively. In addition, the ITR15 of the successful PVI group after cryoballoon ablation was significantly slower than the failed PVI group. ITR15 was a predictor of vagus reflex and the occurrence of vagus reflex group had a slower ITR15 compared to the non-occurrence group. CONCLUSIONS: Thawing rate was a novel predictor of acute PVI and the ITR15 was the most valuable predictor of acute PVI. In addition, ITR15 was a predictive factor ensuring long-term PVI (vagus reflex). Our study showed that thawing rate may serve in the early identification of useless cryoballoon ablation

Observation on the curative effects of two surgical methods for basic intermittent exotropia

AIM:To explore the differences between unilateral recess-resection(R & R)and bilateral lateral rectus recession(BLR-rec)in the treatment of basic intermittent exotropia.METHODS: A retrospective analysis of treatment of basic intermittent exotropia in 89 patients, in which 49 cases underwent unilateral recess-resection, 40 cases underwent bilateral lateral rectus recession of external rectus retroperitoneal surgery January 2013 to January 2015 in our hospital. The stereopsis and strabismus were observed in 1d, 1, 6mo, 1 and 2a after operation.RESULTS: There was no significant difference in the success rate and oblique degree between the two groups after 1d, 1, 6mo, 1 and 2a(all P>0.05), but the success rate of the operation was reducing as time passed. After 2d of the operation, the drift of the R & R group was 12.10±5.74PD and the drift of the BLR-rec group was 7.78±4.21PD, the difference was statistically significant(P=0.021). The R & R group was more likely to cause lateral slanting than BLR-rec group. Two groups of patients with nearly stereopsis were both significantly improved, there was no significant difference between the two groups in the two groups(χ2=4.530, P=0.210). CONCLUSION: The long-term stability of BLR-rec is superior to R & R

Central Role of Adenosine 5′-Phosphosulfate Reductase in the Control of Plant Hydrogen Sulfide Metabolism

Hydrogen sulfide (H2S) has been postulated to be the third gasotransmitter in both animals and plants after nitric oxide (NO) and carbon monoxide (CO). In this review, the physiological roles of H2S in plant growth, development and responses to biotic, and abiotic stresses are summarized. The enzymes which generate H2S are subjected to tight regulation to produce H2S when needed, contributing to delicate responses of H2S to environmental stimuli. H2S occupies a central position in plant sulfur metabolism as it is the link of inorganic sulfur to the first organic sulfur-containing compound cysteine which is the starting point for the synthesis of methionine, coenzyme A, vitamins, etc. In sulfur assimilation, adenosine 5′-phosphosulfate reductase (APR) is the rate-limiting enzyme with the greatest control over the pathway and probably the generation of H2S which is an essential component in this process. APR is an evolutionarily conserved protein among plants, and two conserved domains PAPS_reductase and Thioredoxin are found in APR. Sulfate reduction including the APR-catalyzing step is carried out in chloroplasts. APR, the key enzyme in sulfur assimilation, is mainly regulated at transcription level by transcription factors in response to sulfur availability and environmental stimuli. The cis-acting elements in the promoter region of all the three APR genes in Solanum lycopersicum suggest that multiple factors such as sulfur starvation, cytokinins, CO2, and pathogens may regulate the expression of SlAPRs. In conclusion, as a critical enzyme in regulating sulfur assimilation, APR is probably critical for H2S generation during plants’ response to diverse environmental factors

Mechanistic Insights into Dimethylsulfoniopropionate Lyase DddY, a New Member of the Cupin Superfamily

The marine osmolyte dimethylsulfoniopropionate (DMSP) is one of Earth's most abundant organosulfur molecules. Bacterial DMSP lyases cleave DMSP, producing acrylate and dimethyl sulfide (DMS), a climate-active gas with roles in global sulfur cycling and atmospheric chemistry. DddY is the only known periplasmic DMSP lyase and is present in β-, γ-, δ- and ε-proteobacteria. Unlike other known DMSP lyases, DddY has not been classified into a protein superfamily, and its structure and catalytic mechanism are unknown. Here, we determined the crystal structure of DddY from the γ-proteobacterium Acinetobacter bereziniae originally isolated from human clinical specimens. This structure revealed that DddY contains a cap domain and a catalytic domain with a Zn2 + bound at its active site. We also observed that the DddY catalytic domain adopts a typical β-barrel fold and contains two conserved cupin motifs. Therefore, we concluded that DddY should belong to the cupin superfamily. Using structural and mutational analyses, we identified key residues involved in Zn2 + coordination, DMSP binding and the catalysis of DMSP cleavage, enabling elucidation of the catalytic mechanism, in which the residue Tyr271 of DddY acts as a general base to attack DMSP. Moreover, sequence analysis suggested that this proposed mechanism is common to DddY proteins from β-, γ-, δ- and ε-proteobacteria. The DddY structure and proposed catalytic mechanism provide a better understanding of how DMSP is catabolized to generate the important climate-active gas DMS

The complete genome of Zunongwangia profunda SM-A87 reveals its adaptation to the deep-sea environment and ecological role in sedimentary organic nitrogen degradation

<p>Abstract</p> <p>Background</p> <p><it>Zunongwangia profunda </it>SM-A87, which was isolated from deep-sea sediment, is an aerobic, gram-negative bacterium that represents a new genus of <it>Flavobacteriaceae</it>. This is the first sequenced genome of a deep-sea bacterium from the phylum <it>Bacteroidetes</it>.</p> <p>Results</p> <p>The <it>Z. profunda </it>SM-A87 genome has a single 5 128 187-bp circular chromosome with no extrachromosomal elements and harbors 4 653 predicted protein-coding genes. SM-A87 produces a large amount of capsular polysaccharides and possesses two polysaccharide biosynthesis gene clusters. It has a total of 130 peptidases, 61 of which have signal peptides. In addition to extracellular peptidases, SM-A87 also has various extracellular enzymes for carbohydrate, lipid and DNA degradation. These extracellular enzymes suggest that the bacterium is able to hydrolyze organic materials in the sediment, especially carbohydrates and proteinaceous organic nitrogen. There are two clustered regularly interspaced short palindromic repeats in the genome, but their spacers do not match any sequences in the public sequence databases. SM-A87 is a moderate halophile. Our protein isoelectric point analysis indicates that extracellular proteins have lower predicted isoelectric points than intracellular proteins. SM-A87 accumulates organic osmolytes in the cell, so its extracelluar proteins are more halophilic than its intracellular proteins.</p> <p>Conclusion</p> <p>Here, we present the first complete genome of a deep-sea sedimentary bacterium from the phylum <it>Bacteroidetes</it>. The genome analysis shows that SM-A87 has some common features of deep-sea bacteria, as well as an important capacity to hydrolyze sedimentary organic nitrogen.</p

Structural mechanism for bacterial oxidation of oceanic trimethylamine into trimethylamine N -oxide

Trimethylamine (TMA) and trimethylamine N-oxide (TMAO) are widespread in the ocean and are important nitrogen source for bacteria. TMA monooxygenase (Tmm), a bacterial flavin-containing monooxygenase (FMO), is found widespread in marine bacteria and is responsible for converting TMA to TMAO. However, the molecular mechanism of TMA oxygenation by Tmm has not been explained. Here, we determined the crystal structures of two reaction intermediates of a marine bacterial Tmm (RnTmm) and elucidated the catalytic mechanism of TMA oxidation by RnTmm. The catalytic process of Tmm consists of a reductive half-reaction and an oxidative half-reaction. In the reductive half-reaction, FAD is reduced and a C4a-hydroperoxyflavin intermediate forms. In the oxidative half-reaction, this intermediate attracts TMA through electronic interactions. After TMA binding, NADP+ bends and interacts with D317, shutting off the entrance to create a protected micro-environment for catalysis and exposing C4a-hydroperoxyflavin to TMA for oxidation. Sequence analysis suggests that the proposed catalytic mechanism is common for bacterial Tmms. These findings reveal the catalytic process of TMA oxidation by marine bacterial Tmm and first show that NADP+ undergoes a conformational change in the oxidative half-reaction of FMOs