Diazotrophic Anaeromyxobacter Isolates from Soils.

Biological nitrogen fixation is an essential reaction in a major pathway for supplying nitrogen to terrestrial environments. Previous culture-independent analyses based on soil DNA/RNA/protein sequencing could globally detect the nitrogenase genes/proteins of Anaeromyxobacter (in the class Deltaproteobacteria), commonly distributed in soil environments and predominant in paddy soils; this suggests the importance of Anaeromyxobacter in nitrogen fixation in soil environments. However, direct experimental evidence is lacking; there has been no research on the genetic background and ability of Anaeromyxobacter to fix nitrogen. Therefore, we verified the diazotrophy of Anaeromyxobacter based on both genomic and culture-dependent analyses using Anaeromyxobacter sp. strains PSR-1 and Red267 isolated from soils. Based on the comparison of nif gene clusters, strains PSR-1 and Red267 as well as strains Fw109-5, K, and diazotrophic Geobacter and Pelobacter in the class Deltaproteobacteria contain the minimum set of genes for nitrogenase (nifBHDKEN). These results imply that Anaeromyxobacter species have the ability to fix nitrogen. In fact, Anaeromyxobacter PSR-1 and Red267 exhibited N2-dependent growth and acetylene reduction activity (ARA) in vitro Transcriptional activity of the nif gene was also detected when both strains were cultured with N2 gas as a sole nitrogen source, indicating that Anaeromyxobacter can fix and assimilate N2 gas by nitrogenase. In addition, PSR-1- or Red267-inoculated soil showed ARA activity and the growth of the inoculated strains on the basis of RNA-based analysis, demonstrating that Anaeromyxobacter can fix nitrogen in the paddy soil environment. Our study provides novel insights into the pivotal environmental function, i.e., nitrogen fixation, of Anaeromyxobacter, which is a common soil bacterium.IMPORTANCEAnaeromyxobacter is globally distributed in soil environments, especially predominant in paddy soils. Current studies based on environmental DNA/RNA analyses frequently detect gene fragments encoding nitrogenase of Anaeromyxobacter from various soil environments. Although the importance of Anaeromyxobacter as a diazotroph in nature has been suggested by culture-independent studies, there has been no solid evidence and validation from genomic and culture-based analyses that Anaeromyxobacter fixes nitrogen. This study demonstrates that Anaeromyxobacter harboring nitrogenase genes exhibits diazotrophic ability; moreover, N2-dependent growth was demonstrated in vitro and in the soil environment. Our findings indicate that nitrogen fixation is important for Anaeromyxobacter to survive under nitrogen-deficient environments and provide a novel insight into the environmental function of Anaeromyxobacter, which is a common bacterium in soils.

Inducible expression of agar-degrading genes in a marine bacterium Catenovulum maritimus Q1T and characterization of a ß-agarase.

Agar-degrading bacteria are crucial drivers for the carbon cycle in the marine environments due to their ability that use algae as a carbon source. Although numerous agar-degrading bacteria and agarases have been reported, little is known about expression levels of agar-degrading genes in wild strains. Here, the genome of an agar-hydrolyzing marine bacterium, Catenovulum maritimus Q1T, was sequenced and annotated with 11 agarase and 2 neoagarooligosaccharide hydrolase genes. Quantitative PCR revealed that all the annotated agar-degrading genes were expressed consistently that initially upregulated and then gradually downregulated under agarose induction. Moreover, the presence of glucose inhibited the agar-degrading ability, in terms of both gene expression and enzymatic activity. These facts indicated the agar-degrading ability of wild bacteria was mainly induced by agarose and repressed by the available carbon source. Additionally, a ß-agarase, AgaQ1, belonging to the GH16 family, with high expression in strain Q1T, was cloned and characterized. Biochemical analysis showed that the recombinant AgaQ1 was substrate-specific, yielding neoagarotetraose and neoagarohexaose as the main products. It exhibited optimal activity at 40 °C, pH 8.0, and an agarose concentration of 1.6% (w/v). Besides, AgaQ1 showed a high-specific activity (757.7 U/mg) and stable enzymatic activity under different ion or agent treatments; thus, AgaQ1 has great potential in industrial applications. KEY POINTS: • The genome of C. maritimus Q1T was sequenced and annotated with 11 agarases and 2 Nabh genes. • The expression of agar-degrading genes in the strain C. maritimus Q1T was induced by agarose. • Glucose was the carbon source utilized prior to agarose for bacterial growth. • A ß-agarase, AgaQ1, with high expression and activity was identified.

Salegentibacter sediminis sp. nov., a marine bacterium of the family Flavobacteriaceae isolated from coastal sediment.

A Gram-stain-negative, aerobic, non-motile, rod-shaped (0.2-0.3×0.8-1.4 µm) and yellow-pigmented bacterium, designated K5023T, was isolated from marine sediment obtained off the coast of Weihai, China. Strain K5023T was found to grow at 16-37 °C (optimum, 33 °C), at pH 6.5-8.0 (optimum, 7.0-7.5) and in the presence of 1-10 % (w/v) NaCl (optimum, 5 %). Cells were oxidase-positive and catalase-negative. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain K5023T is a member of the genus Salegentibacter and exhibited the hightest sequence similarity to Salegentibacter flavus DSM 22702T (97.0 %). Menaquinone-6 (MK-6) was detected as the major respiratory quinone. The dominant cellular fatty acids were iso-C15 : 0 and anteiso-C15 : 0. The DNA G+C content of strain K5023T was 40.1 mol%. The polar lipids included one phosphatidylethanolamine, three phospholipids and four unidentified lipids. Based on the phylogenetic and phenotypic characteristics, strain K5023T is considered to represent a novel species of the genus Salegentibacter, for which the name Salegentibacter sediminis sp. nov. is proposed. The type strain is K5023T (=KCTC 52477T=MCCC 1H00173T).

Geofilum rhodophaeum sp. nov., isolated from coastal sediment.

A novel Gram-stain-negative, facultatively anaerobic, filamentous and rose-brown pigmented bacterium, designated strain HF401T, was isolated from marine sediment off the coast of Weihai, China. The isolate grew at temperatures between 4 and 45 °C (optimal growth at 33 °C), at pH 6.5-8.5 (optimal growth at pH 7.5) and with 0.5-6.0 % (w/v) NaCl (optimal growth at 3.0 %). The predominant menaquinone was menaquinone 7 (MK-7). The G+C content of the genomic DNA was 50.8 mol% (from high-performance liquid chromatography). The major fatty acids were iso-C15 : 0, C16:0, anteiso-C15 : 0 and summed feature 3 (C16 : 1ω7c and/or iso-C15 : 0 2OH). The major polar lipids were phosphatidylethanolamine, phospholipid and an unidentified lipid. Phylogenetic analysis of 16S rRNA gene sequences indicated that strain HF401T formed a distinct branch with Geofilum rubicundum JCM 15548T in the family Marinilabiliaceae. The most closely related strains of strain HF401T were Natronoflexuspectinivorans AP1T (96.2 % 16S rRNA gene sequence similarity), G. rubicundum JCM 15548T (96.2 %) and Alkalitaleasaponilacus SC/BZ-SP2T (96.0 %). Average nucleotide identity (ANI) values between strain HF401T and G. rubicundum JCM 15548T showed a relatedness of 71.3 % (ANIb) and 86.0 % (ANIm). The percentage of conserved proteins (POCP) value between strain HF401T and G. rubicundum JCM 15548T was 61.2 %. Based on polyphasic analysis, especially the phylogenetic relationships and the higher POCP value, strain HF401T is considered to represent a novel species in the genus Geofilum, for which the name Geofilum rhodophaeum sp. nov. is proposed. The type strain of Geofilum rhodophaeum is HF401T (KCTC 42595T=MCCC 1H00119T).

Tenacibaculum agarivorans sp. nov., an agar-degrading bacterium isolated from marine alga Porphyra yezoensis Ueda.

A novel Gram-stain-negative, aerobic, rod-shaped, non-flagellated and agar-digesting marine bacterium, designated as HZ1T, was isolated from the marine alga Porphyra yezoensis Ueda (AST58-103) collected from the coastal area of Weihai, PR China. Phylogenetic analysis based on 16S rRNA gene sequences placed HZ1T in the genus Tenacibaculum, and it formed a distinct clade in the phylogenetic tree with the type strains of Tenacibaculum amylolyticum and Tenacibaculum skagerrakense, with 97.0 % and 96.7 % 16S rRNA gene sequence similarities, respectively. The DNA G+C content of the isolate was 31.8 mol%. HZ1T contained MK-6 as the predominant menaquinone and iso-C15 : 0, summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c), iso-C17 : 0 3-OH and iso-C15 : 1G as the major fatty acids. The major polar lipids were phosphatidylethanolamine, four unidentified lipids and five unidentified aminolipids. On the basis of the results of the phylogenetic analysis and phenotypic properties, it is concluded that HZ1T represents a novel species of the genus Tenacibaculum, for which the name Tenacibaculumagarivorans sp. nov. is proposed. The type strain is HZ1T (=MCCC 1H00174T=KCTC 52476T).

Colwellia agarivorans sp. nov., an agar-digesting marine bacterium isolated from coastal seawater.

A novel Gram-stain-negative, facultatively anaerobic, yellowish and agar-digesting marine bacterium, designated strain QM50T, was isolated from coastal seawater in an aquaculture site near Qingdao, China. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the isolate represented a member of the genus Colwellia and exhibited the highest sequence similarity (97.4 %) to Colwellia aestuarii SMK-10T. Average nucleotide identity (ANI) values based on draft genome sequences between strain QM50T and C. aestuarii KCTC 12480T showed a relatedness of 72.0 % (ANIb) and 85.1 % (ANIm). Cells of strain QM50T were approximately 0.3-0.6×0.8-2.5 µm in size and motile by means of a polar flagellum. Growth occurred in the presence of 1.0-6.0 % (w/v) NaCl (optimum, 2.0-3.0 %), at pH 6.5-8.5 (optimum, pH 7.0) and at 4-37 °C (optimum, 28-30 °C). Strain QM50T was found to contain ubiquinone 8 (Q-8) as the predominant ubiquinone and summed feature 3 (C16 : 1ω7c and/or iso-C15 : 0 2-OH), C16 : 0 and C17 : 1ω8c as the main cellular fatty acids. Phosphatidylethanolamine and phosphatidylglycerol were found to be major polar lipids. The DNA G+C content of strain QM50T was determined to be 35.7 mol%. On the basis of phylogenetic and phenotypic data, strain QM50T represents a novel species of the genus Colwellia, for which the name Colwellia agarivorans sp. nov. is proposed. The type strain is QM50T (=KCTC 52273T=MCCC 1H00143T).

[Effects of Huatan Tongluo Recipe on IL-1ß-induced Proliferation of Rheumatoid Arthritis Synovial Fibroblasts and the Production of TNF-α and aFGF].

Objective To observe the effects of Huatan Tongluo Recipe (HTTLR) on the proliferation of IL-ß p induced rheumatoid arthritis synovial fibroblast ( RASFB) and secretion of necrosis factor α (TNF-α) and acidic fibroblast growth factor (aFGF) in vitro. Methods RASFB cell line was cultured in vitro and stimulated by IL-1ß. The proliferation of RASFB was detected using WST-1 after adding IL-1ß with final concentrations of 1 , 5, 10, 20 µg/L for 24 and 48 h respectively. Then 20 µg/L IL-1ß recruited as induction dose was set up as IL-1ß group. High, middle, low dose HTTLR groups were set up by adding HT- TLR decoction with final concentration of 5%, 2%, 1% (V/V) , respectively for 24 and 48 h. A blank con- trol group was also set up. The proliferation rates were compared. Contents of TNF-α and aFGF were detected in each group using ELISA. mRNA expressions of TNF-α and aFGF were detected using RT-PCR. Results The proliferation rates of RASFB at 24 h and 48 h were lower at 1 µg/L IL-1 ß than at 5, 10, 20 µg/L IL-1ß (P <0. 01). The proliferation rate of RASFB was higher at 10 and 20 µg/L IL-1ß than at 5 µg/L IL-1ß (P <0. 01). Besides, the proliferation rate of RASFB was higher at 20 µg/L IL-1ß than at 10 µg/L IL-1 ß (P <0. 01). The proliferation rate of RASFB was higher at 48 h than at 24 h (P <0. 01). Com- pared with the high dose HTTLR group, the proliferation rate of RASFB was lowered in middle and low dose HTTLR groups (P <0. 01). Besides, IL-1ß induced proliferation rate of RASFB was obviously reduced in the middle dose HTTLR group (P <0. 01). Compared with the blank control group, mRNA ex- pressions of TNF-α and aFGF and their contents were elevated in the IL-1ß group at 24 and 48 h (P < 0. 05). Compared with the IL-1 ß group, mRNA expressions of TNF-α- and aFGF and their contents, except TNF-α- mRNA expression in the low dose HTTLR group at 24 h, were all obviously lowered in 3 dose HTTLR groups at 24 h and 48 h (P <0. 05). Compared with the high dose HTTLR group, mRNA expressions of TNF-(α and aFGF increased in middle and low dose HTTLR groups at 24 h and 48 h; TNF-α content in the low dose HTTLR group at 24 h; contents of TNF-α and aFGF in middle and low dose HTTLR groups at 24 h and 48 h all increased (P <0. 05). Conclusion The mechanism of HTTLR treatment for RA might be related to inhibiting RASFB proliferation, and decreasing mRNA expressions of TNF-α and aFGF as well as their protein secretion.

Marinifilum albidiflavum sp. nov., isolated from coastal sediment.

A novel Gram-stain-negative, facultatively anaerobic, filamentous, and yellowish-white-pigmented marine bacterium, designated strain FB208T, was isolated from marine sediment obtained off the coastal area of Weihai, China. Cells of strain FB208T were filamentous during exponential growth, fragmented to rods in the stationary growth phase and became spherical in aged cultures. It grew optimally at 33 °C, at pH 7.0-7.5 and in the presence of 2.0-3.0 % (w/v) NaCl. Based on the 16S rRNA gene sequence, strain FB208T was found to be closely related to Marinifilum flexuosum DSM 21950T (96.9 % similarity) and Marinifilum fragile JCM 15579T (96.4 %), with less than 90.0 % sequence similarity to other genera of the class Bacteroidia. Phylogenetic analysis, also based on 16S rRNA gene sequences, placed strain FB208T in the genus Marinifilum, family Marinifilaceae. The predominant isoprenoid quinone of strain FB208T was identified as menaquinone MK-7. The main cellular fatty acids were iso-C15 : 0, iso-C17 : 0 3-OH and iso-C17 : 1ω9c, and the major polar lipids were an unidentified lipid and aminophospholipid. The G+C content of the genomic DNA was 43.8 mol%. Based on these phylogenetic and phenotypic data, strain FB208T represents a novel species of the genus Marinifilum, for which the name Marinifilum albidiflavum sp. nov. is proposed. The type strain is FB208T (=KCTC 42591T=MCCC 1H00113T).

Nocardioides gilvus sp. nov., isolated from Namtso Lake.

A Gram-stain positive, facultatively anaerobic, non-motile and rod to coccoid-shaped bacterium, designated XZ17(T), was isolated from Namtso Lake of Tibet, China. Strain XZ17(T) grew optimally at pH 8.0-9.0, at 30-33 °C and in the presence of 0-1.0 % (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences demonstrated that strain XZ17(T) belongs to the genus Nocardioides in the family Nocardioidaceae. Strain XZ17(T) shared pairwise 16S rRNA gene sequence similarities of 97.2, 96.8, 96.5, 96.4 and <96.0 % to Nocardioides solisilvae KCTC 39528(T), Nocardioides daejeonensis JCM 16922(T), Nocardioides jensenii NCIB 9770(T), Nocardioides dubius KCTC 9992(T) and other Nocardioides species, respectively. It contained MK-8 (H4) as the predominant menaquinone and C17:1 ω8c, C15:0, C17:0 and C18:1 ω9c as the major fatty acid. The strain had cell wall peptidoglycan based on LL-2,6-diaminopimelic acid. The polar lipids of strain XZ17(T) comprised diphosphatidylglycerol, phosphatidylglycerol, three unidentified phospholipids, three unidentified glycolipids and two unidentified lipids. The DNA G+C content of strain XZ17(T) was 68.9 mol%. Based on distinctive phenotypic characteristics, phylogenetic analysis and chemotaxonomic data, it can be concluded that strain XZ17(T) represents a novel species within the genus Nocardioides, for which the name Nocardioides gilvus sp. nov. is proposed. The type strain is strain XZ17(T) (=KCTC 39561(T) = MCCC 1H00114(T)).

Pistricoccus aurantiacus gen. nov., sp. nov., a moderately halophilic bacterium isolated from a shark.

A novel Gram-stain negative, non-motile, moderately halophilic, facultatively anaerobic and spherical bacterium designated strain SS9T was isolated from the gill homogenate of a shark. Cells of SS9T were observed to be 0.8-1.2 µm in diameter. The strain was found to grow optimally at 33 °C, pH 7.0-8.0 and in the presence of 6.0 % (w/v) NaCl. On the basis of 16S rRNA gene phylogeny, strain SS9T can be affiliated with the family Halomonadaceae and is closely related to Chromohalobacter marismortui NBRC 103155T (95.6 % sequence similarity), Halomonas ilicicola SP8T (95.6 %) and Chromohalobacter salexigens DSM 3043T (95.5 %). Multilocus sequence analysis of strain SS9T using the housekeeping genes 16S rRNA, 23S rRNA, gyrB, rpoD and secA revealed the strain's distinct phylogenetic position, separate from other known genera of the family Halomonadaceae. Strain SS9T was found to contain ubiquinone-9 (Q-9) as the predominant ubiquinone and C18:1 ω7c, C16:0 and summed feature 3 (C16:1 ω7c and/or iso-C15:0 2-OH) as the major fatty acids. The major polar lipids of strain SS9T were identified as phosphatidylglycerol and phosphatidylethanolamine. The DNA G + C content of strain SS9T was determined to be 60.4 mol%. It is evident from phylogenetic, genotypic, phenotypic and chemotaxonomic results that strain SS9T represents a novel species in a new genus, for which the name Pistricoccus aurantiacus gen. nov., sp. nov. is proposed. The type strain is SS9T (=KCTC 42586T = MCCC 1H00111T).

Thalassotalea sediminis sp. nov., isolated from coastal sediment.

A novel Gram-stain negative, facultatively anaerobic, rod-shaped and yellowish-white-pigmented marine bacterium, designated strain N211(T), was isolated from marine sediment obtained off the coastal area of Weihai, China. The cells are approximately 0.4-0.9 × 1.8-3.5 µm in size and motile by means of a polar flagellum. The strain grows optimally at 33 °C, pH 7.5-8.5 and in the presence of 3.0 % (w/v) NaCl. A neighbour-joining phylogenetic tree based on 16S rRNA gene sequences indicated that strain N211(T) fell within the clade comprising the type strains of species of the genus Thalassotalea. Strain N211(T) was most closely related to Thalassotalea ganghwensis DSM 15355(T) (96.4 %) based on the 16S rRNA gene sequence, and shared 94.4-96.4 % similarity with type strains of all members of the genus Thalassotalea. The predominant isoprenoid quinone of strain N211(T) was identified as ubiquinone-8 (Q-8). The major polar lipids were found to be phosphatidylethanolamine, phosphatidylglycerol and an unidentified lipid. C17:1 w8c, summed feature 3 (C16:1 w7c and/or iso-C 15:0 2-OH) and C16:0 were found to be main cellular fatty acids. The G+C content of the genomic DNA is 39.1 mol%. It is evident from phenotypic data and phylogenetic inference that strain N211(T) represents a novel species of the genus Thalassotalea, for which the name T. sediminis sp. nov. is proposed. The type strain is N211(T) (=KCTC 42588(T) = MCCC 1H00116(T)).

Short-chain fatty acids (SCFAs) as potential resuscitation factors that promote the isolation and culture of uncultured bacteria in marine sediments.

Many marine bacteria are difficult to culture because they are dormant, rare or found in low-abundances. Enrichment culturing has been widely tested as an important strategy to isolate rare or dormant microbes. However, many more mechanisms remain uncertain. Here, based on 16S rRNA gene high-throughput sequencing and metabolomics technology, it was found that the short-chain fatty acids (SCFAs) in metabolites were significantly correlated with uncultured bacterial groups during enrichment cultures. A pure culture analysis showed that the addition of SCFAs to media also resulted in high efficiency for the isolation of uncultured strains from marine sediments. As a result, 238 strains belonging to 10 phyla, 26 families and 82 species were successfully isolated. Some uncultured rare taxa within Chlorobi and Kiritimatiellaeota were successfully cultured. Amongst the newly isolated uncultured microbes, most genomes, e.g. bacteria, possess SCFA oxidative degradation genes, and these features might aid these microbes in better adapting to the culture media. A further resuscitation analysis of a viable but non-culturable (VBNC) Marinilabiliales strain verified that the addition of SCFAs could break the dormancy of Marinilabiliales in 5 days, and the growth curve test showed that the SCFAs could shorten the lag phase and increase the growth rate. Overall, this study provides new insights into SCFAs, which were first studied as resuscitation factors in uncultured marine bacteria. Thus, this study can help improve the utilisation and excavation of marine microbial resources, especially for the most-wanted or key players. Supplementary Information: The online version contains supplementary material available at 10.1007/s42995-023-00187-w.

Resatorvid protects against hypoxic-ischemic brain damage in neonatal rats.

Secondary brain damage caused by hyperactivation of autophagy and inflammatory responses in neurons plays an important role in hypoxic-ischemic brain damage (HIBD). Although previous studies have implicated Toll-like receptor 4 (TLR4) and nuclear factor kappa-B (NF-κB) in the neuroinflammatory response elicited by brain injury, the role and mechanisms of the TLR4-mediated autophagy signaling pathway in neonatal HIBD are still unclear. We hypothesized that this pathway can regulate brain damage by modulating neuron autophagy and neuroinflammation in neonatal rats with HIBD. Hence, we established a neonatal HIBD rat model using the Rice-Vannucci method, and injected 0.75, 1.5, or 3 mg/kg of the TLR4 inhibitor resatorvid (TAK-242) 30 minutes after hypoxic ischemia. Our results indicate that administering TAK-242 to neonatal rats after HIBD could significantly reduce the infarct volume and the extent of cerebral edema, alleviate neuronal damage and neurobehavioral impairment, and decrease the expression levels of TLR4, phospho-NF-κB p65, Beclin-1, microtubule-associated protein l light chain 3, tumor necrosis factor-α, and interleukin-1ß in the hippocampus. Thus, TAK-242 appears to exert a neuroprotective effect after HIBD by inhibiting activation of autophagy and the release of inflammatory cytokines via inhibition of the TLR4/NF-κB signaling pathway. This study was approved by the Laboratory Animal Ethics Committee of Affiliated Hospital of Yangzhou University, China (approval No. 20180114-15) on January 14, 2018.

[Corrigendum] Effects of rotigaptide (ZP123) on connexin43 remodeling in canine ventricular fibrillation.

Mol Med Rep 12: [Related article:] 5746­5752, 2015; DOI: 10.3892/mmr.2015.4193 Following the publication of this article on-line ahead of print, an interested reader drew to our attention some anomalies associated with the presentation of Fig. 1. In the lower panel, the fourth image from the left resembled a mirror image representation of the image in the first panel; the fifth image from the left bore a marked resemblance to a section of the third image, albeit displaced at an angle and with a different magnification; and an internal office investigation drew our attention to the fact that the sixth image in the upper panel resembled a section of the image in the third panel, although rotated through 180°.

Effects of rotigaptide (ZP123) on connexin43 remodeling in canine ventricular fibrillation.

The present study investigated the effects of rotigaptide (ZP123) on the expression, distribution and phosphorylation of connexin43 (Cx43) in myocardial cell membranes in cardioversion of ventricular fibrillation (VF). A model of prolonged VF (8, 12 and 30 min) was established in mongrel dogs (n=8/group), following treatment with ZP123 or normal saline (NS control). A sham control was included. Cardiopulmonary resuscitation was begun at the start of VF followed by defibrillation. Animals received a maximum of three defibrillations of increasing energy (70, 100 and 150 J biphasic shock) as required. The average defibrillation energy, defibrillation success rate, return of spontaneous circulation and survival rate were recorded. Cx43 and phosphorylated (p-)Cx43 expression in cardiomyocyte membranes was detected by western blot and immunofluorescence analyses. Compared with the NS-treated control groups, the success defibrillation rate in the 8-min and 12-min ZP123 groups was significantly higher (P<0.05), while the average defibrillation energy was significantly lower (P<0.05). Cx43 expression in the VF groups was significantly lower than that in the sham control group (P<0.05). Cx43 expression was higher in the 12-min and 30-min ZP123 groups than that in the NS control group (P<0.05), while p-Cx43 expression decreased, although the levels were significantly higher than those in the control groups (P<0.05). Cx43 expression was positively correlated with the defibrillation success rate (r=0.91; P<0.01) and negatively with the mean defibrillation energy (r=-0.854; P<0.01), while p-Cx43 expression was positively correlated with the success rate of the previous three defibrillations (r=0.926; P<0.01).In conclusion, ZP123 reduced Cx43 remodeling through regulating the expression, distribution and phosphorylation of Cx43, thereby reducing the defibrillation energy required for successful cardioversion.

Effect of pulmonary vein isolation on atrial fibrillation recurrence after ablation of paroxysmal supraventricular tachycardia in patients with high dispersion of atrial refractoriness.

PURPOSE: This study aimed to assess pulmonary vein isolation (PVI) efficacy on atrial fibrillation (AF) recurrence and to determine a predictive dispersion of atrial refractoriness (dERP) value for performing PVI in paroxysmal supraventricular tachycardia (PSVT) patients. METHODS: Of 67 PSVT patients with past AF episodes who underwent accessory pathway (AP) or slow pathway of atrioventricular node ablation, 63 (4 lost to follow-up or death) were assigned into two groups (A and B; 29 and 34 patients, respectively) based on whether they underwent or not subsequent PVI, and all were followed-up up to 3 years. Atrial effective refractory period (AERP) and dERP were measured during the ablation procedure. RESULTS: In receiver operating characteristic (ROC) curve analysis, dERP = 74.5 ms effectively predicted AF recurrence in PSVT patients (p = 0.003). Difference in AF recurrence rate between groups did not reach statistical significance (17.2%, 5/29 vs. 29.4%, 10/34, p = 0.203). AF recurrence rate was lower in patients with dERP >74.5 ms who underwent AP or slow-pathway ablation with vs. without PVI (18.2%, 2/11 vs. 77.8%, 7/9, p = 0.012). CONCLUSIONS: PVI addition after successful AP or slow pathway of atrioventricular node ablation significantly reduced AF recurrence in PSVT patients with high atrial vulnerability (dERP >74.5 ms).

Atrial conduction delay predicts atrial fibrillation in paroxysmal supraventricular tachycardia patients after radiofrequency catheter ablation.

This study aimed to assess whether intra- and inter-atrial conduction delay could predict atrial fibrillation (AF) for paroxysmal supraventricular tachycardia (PSVT) patients after successful treatment by radiofrequency catheter ablation (RFCA). Echocardiography examination was performed on 524 consecutive PSVT patients (15 patients were excluded). Left atrial dimension, right atrial diameter and intra- and inter-atrial conduction delay were measured before ablation. Patients were divided into group A (n = 32): occurrence of AF after the ablation and group B (n = 477): remained in sinus rhythm during follow-up. Receiver operating characteristic (ROC) curve analysis was performed to estimate the predictive value of intra- and inter-atrial conduction delay. Both intra- and inter-atrial conduction delay were higher in group A than in group B (4.79 ± 0.30 msec vs. 4.56 ± 0.32 msec; 21.98 ± 1.32 msec vs. 20.01 ± 1.33; p < 0.05). Binary logistic regression analysis showed that intra- and inter-atrial conduction were significant influential factors for the occurrence of AF (odds ratio [OR] = 13.577, 95% confidence interval [CI], 3.469-48.914; OR = 2.569, 95% CI, 1.909-3.459, p < 0.05). The ROC cure analysis revealed that intra-atrial conduction delay ≥ 4.45 msec and inter-atrial conduction delay ≥ 20.65 were the most optimal cut-off value for predicting AF in PSVT patients after RFCA. In conclusion, this is the first study to show that the intra- and inter-atrial conduction delay could effectively predict AF in post-ablation PSVT patients.