12(S)-Hydroxyeicosatetraenoic acid induces cAMP production via increasing intracellular calcium concentration

AbstractWe have found that a 12-lipoxygenase metabolite of arachidonic acid, 12(S)-hydroxy-5Z,8Z,10E,14Z-eicosatetraenoic acid (12-HETE), induces cAMP production in human normal fibroblast TIG-1 cells. This phenomenon was not observed in other cells tested including human embryonic kidney HEK293 cells. We have speculated that this specific response might be influenced by the kinds of isoform of adenylyl cyclase (AC) present in cells. We found that TIG-1 cells specifically expressed type VIII AC. As type VIII AC is known to be activated by an increase of calcium concentration, we determined the change of intracellular Ca2+ concentration after the addition of 12-HETE. It was elevated not only in TIG-1 cells, but also HEK293 cells, which did not respond to 12-HETE to produce cAMP. The addition of a calcium ionophore elevated the concentration of intracellular cAMP in TIG-1 cells, but it was without effect in HEK293 cells. To show that the expression of this particular isoform of AC is responsible for the positive response to 12-HETE, we transfected this AC isoform into HEK293 cells. The type VIII AC-transfected cells, in contrast to the mock-transfected ones, became very responsive to 12-HETE to produce cAMP. Taken all together the data would strongly suggest that 12-HETE specifically activates type VIII AC via increasing intracellular Ca2+ concentration

DNA methyltransferase 3B plays a protective role against hepatocarcinogenesis caused by chronic inflammation via maintaining mitochondrial homeostasis

Most hepatocellular carcinomas (HCCs) develop on the basis of chronic hepatitis, but the mechanism of epigenetic regulation in inflammatory hepatocarcinogenesis has yet to be elucidated. Among de novo DNA methyltransferases (DNMTs), DNMT3B has lately been reported to act specifically on actively transcribed genes, suggesting the possibility that it plays a role in the pathogenesis of cancer. We confirmed that DNMT3B isoforms lacking its catalytic domain were highly expressed in HCCs compared with non-tumorous liver tissue. To elucidate the role of DNMT3B in hepatocarcinogenesis, we generated a genetically engineered mouse model with hepatocyte-specific Dnmt3b deletion. The liver of the Dnmt3b-deficient mice exhibited an exacerbation of thioacetamide-induced hepatitis, progression of liver fibrosis and a higher incidence of HCC compared with the liver of the control mice. Whole-genome bisulfite sequencing verified a lower CG methylation level in the Dnmt3b-deficient liver, demonstrating differentially methylated regions throughout the genome. Transcriptome analysis revealed decreased expression of genes related to oxidative phosphorylation in the Dnmt3b-deficient liver. Moreover, primary hepatocytes isolated from the Dnmt3b-deficient mice showed reduced mitochondrial respiratory capacity, leading to the enhancement of oxidative stress in the liver tissue. Our findings suggest the protective role of DNMT3B against chronic inflammation and HCC development via maintaining mitochondrial homeostasis

National survey of catheter ablation for atrial fibrillation: The Japanese catheter ablation registry of atrial fibrillation (J-CARAF)

AbstractTo assess the current status of atrial fibrillation (AF) ablation in Japan, the Japanese Heart Rhythm Society (JHRS) instituted a national registry, the Japanese Catheter Ablation Registry of AF (J-CARAF).MethodsUsing an online questionnaire, the JHRS invited electrophysiology centers in Japan to voluntarily and retrospectively register data regarding the AF ablation procedures performed in September, 2011.ResultsA total of 128 centers submitted data regarding AF ablation procedures in 932 patients (age 62.1±10.4 years; male 76.8%; paroxysmal AF 65.7%, CHADS2 score 1.0±1.0). The majority received oral anticoagulant therapy during and following the procedure (68.9% and 97.5%, respectively). Pulmonary vein isolation (PVI) was performed in 97.5% of the patients; ipsilateral encircling PVI was the preferred technique (79.7%). Three-dimensional (3D) mapping systems and irrigated-tip catheters were used in 94.8% and 87.7% of the procedures, respectively. Ablation methods other than PVI were performed in 78.8% of all the patients and 73.5% of the patients with paroxysmal AF. Acute complications were reported in 6.2% of the patients, but no early deaths were recorded.ConclusionsIpsilateral encircling PVI, using 3D mapping and irrigated-tip catheters, is the standard AF ablation method in Japan. However, adjunctive ablations were performed frequently, even in patients with paroxysmal AF

Mutational spectrum of hepatitis C virus in patients with chronic hepatitis C determined by single molecule real-time sequencing

The emergence of hepatitis C virus (HCV) with resistance-associated substitution (RAS), produced by mutations in the HCV genome, is a major problem in direct acting antivirals (DAA) treatment. This study aimed to clarify the mutational spectrum in HCV-RNA and the substitution pattern for the emergence of RASs in patients with chronic HCV infection. HCV-RNA from two HCV replicon cell lines and the serum HCV-RNA of four non-liver transplant and four post-liver transplant patients with unsuccessful DAA treatment were analyzed using high-accuracy single-molecule real-time long-read sequencing. Transition substitutions, especially A>G and U>C, occurred prominently under DAAs in both non-transplant and post-transplant patients, with a mutational bias identical to that occurring in HCV replicon cell lines during 10-year culturing. These mutational biases were reproduced in natural courses after DAA treatment. RASs emerged via both transition and transversion substitutions. NS3-D168 and NS5A-L31 RASs resulted from transversion mutations, while NS5A-Y93 RASs was caused by transition substitutions. The fidelity of the RNA-dependent RNA polymerase, HCV-NS5B, produces mutational bias in the HCV genome, characterized by dominant transition mutations, notably A>G and U>C substitutions. However, RASs are acquired by both transition and transversion substitutions, and the RASs-positive HCV clones are selected and proliferated under DAA treatment pressure

Quasiparticle excitation in and around the vortex core of underdoped YBa_2Cu_4O_8 studied by site-selective NMR

We report a site-selective ^{17}O spin-lattice relaxation rate T_1^{-1} in the vortex state of underdoped YBa_2Cu_4O_8. We found that T_1^{-1} at the planar sites exhibits an unusual nonmonotonic NMR frequency dependence. In the region well outside the vortex core, T_1^{-1} cannot be simply explained by the density of states of the Doppler-shifted quasiparticles in the d-wave superconductor. Based on T_1^{-1} in the vortex core region, we establish strong evidence that the local density of states within the vortex core is strongly reduced.Comment: 5 pages, 3 figure

LDL-C/HDL-C Ratio Predicts Carotid Intima-Media Thickness Progression Better Than HDL-C or LDL-C Alone

High-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) are strong predictors of atherosclerosis. Statin-induced changes in the ratio of LDL-C to HDL-C (LDL-C/HDL-C) predicted atherosclerosis progression better than LDL-C or HDL-C alone. However, the best predictor of subclinical atherosclerosis remains unknown. Our objective was to investigate this issue by measuring changes in carotid intima-media thickness (IMT). A total of 1,920 subjects received health examinations in 1999, and were followed up in 2007. Changes in IMT (follow-up IMT/baseline IMT × 100) were measured by ultrasonography. Our results showed that changes in IMT after eight years were significantly related to HDL-C (inversely, P < 0.05) and to LDL-C/HDL-C ratio (P < 0.05). When the LDL-C/HDL-C ratios were divided into quartiles, analysis of covariance showed that increases in the ratio were related to IMT progression (P < 0.05). This prospective study demonstrated the LDL-C/HDL-C ratio is a better predictor of IMT progression than HDL-C or LDL-C alone

Charged Vortices in High Temperature Superconductors Probed by NMR

We report a first experimental evidence that a vortex in the high temperature superconductors (HTSC) traps a finite electric charge from the high resolution measurements of the nuclear quadrupole frequencies. In slightly overdoped YBa_2Cu_3O_7 the vortex is negatively charged by trapping electrons, while in underdoped YBa_2Cu_4O_8 it is positively charged by expelling electrons. The sign of the trapped charge is opposite to the sign predicted by the conventional BCS theory. Moreover, in both materials, the deviation of the magnitude of the charge from the theory is also significant. These unexpected features can be attributed to the novel electronic structure of the vortex in HTSC.Comment: 6 pages, 7 figures, to be published in Phys Rev.