Reversible RNA phosphorylation stabilizes tRNA for cellular thermotolerance.

Post-transcriptional modifications have critical roles in tRNA stability and function1-4. In thermophiles, tRNAs are heavily modified to maintain their thermal stability under extreme growth temperatures5,6. Here we identified 2'-phosphouridine (Up) at position 47 of tRNAs from thermophilic archaea. Up47 confers thermal stability and nuclease resistance to tRNAs. Atomic structures of native archaeal tRNA showed a unique metastable core structure stabilized by Up47. The 2'-phosphate of Up47 protrudes from the tRNA core and prevents backbone rotation during thermal denaturation. In addition, we identified the arkI gene, which encodes an archaeal RNA kinase responsible for Up47 formation. Structural studies showed that ArkI has a non-canonical kinase motif surrounded by a positively charged patch for tRNA binding. A knockout strain of arkI grew slowly at high temperatures and exhibited a synthetic growth defect when a second tRNA-modifying enzyme was depleted. We also identified an archaeal homologue of KptA as an eraser that efficiently dephosphorylates Up47 in vitro and in vivo. Taken together, our findings show that Up47 is a reversible RNA modification mediated by ArkI and KptA that fine-tunes the structural rigidity of tRNAs under extreme environmental conditions.

Publisher Correction: A weak topological insulator state in quasi-one-dimensional bismuth iodide.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

A weak topological insulator state in quasi-one-dimensional bismuth iodide.

The major breakthroughs in understanding of topological materials over the past decade were all triggered by the discovery of the Z2-type topological insulator-a type of material that is insulating in its interior but allows electron flow on its surface. In three dimensions, a topological insulator is classified as either 'strong' or 'weak'1,2, and experimental confirmations of the strong topological insulator rapidly followed theoretical predictions3-5. By contrast, the weak topological insulator (WTI) has so far eluded experimental verification, because the topological surface states emerge only on particular side surfaces, which are typically undetectable in real three-dimensional crystals6-10. Here we provide experimental evidence for the WTI state in a bismuth iodide, ß-Bi4I4. Notably, the crystal has naturally cleavable top and side planes-stacked via van der Waals forces-which have long been desirable for the experimental realization of the WTI state11,12. As a definitive signature of this state, we find a quasi-one-dimensional Dirac topological surface state at the side surface (the (100) plane), while the top surface (the (001) plane) is topologically dark with an absence of topological surface states. We also find that a crystal transition from the ß-phase to the α-phase drives a topological phase transition from a nontrivial WTI to a normal insulator at roughly room temperature. The weak topological phase-viewed as quantum spin Hall insulators stacked three-dimensionally13,14-will lay a foundation for technology that benefits from highly directional, dense spin currents that are protected against backscattering.

[Surgical Left Atrial Ablation Through the Left Atrial Appendage During Aortic Valve Replacement].

This is a 2-case report of concomitant left atrial( LA) surgical ablation through the left atrial appendage( LAA) for atrial fibrillation( AF) during aortic valve replacement( AVR). Case 1, a 74-year-old man, and Case 2, an 85-years-old woman, were presented for AVR and AF. Under the cardio-pulmonary bypass, right and left pulmonary vein isolations( PVIs) were performed with radiofrequency( RF) ablation devices. Through the opened LAA, an RF lesion was placed to connect the bilateral PVIs and the LAA, and another RF line was placed toward the mitral annulus. A right atrial( RA) isthmus ablation was also performed through a RA incision. Postoperatively, sinus rhythm and both RA and LA contraction were obtained, and have been maintained for 7.5 and 5 years without classⅠ/Ⅲ antiarrhythmic drugs in Case 1 and 2, respectively. This procedure is considered to be effective and safe, although further study is needed.

Visualization of the strain-induced topological phase transition in a quasi-one-dimensional superconductor TaSe3.

Control of the phase transition from topological to normal insulators can allow for an on/off switching of spin current. While topological phase transitions have been realized by elemental substitution in semiconducting alloys, such an approach requires preparation of materials with various compositions. Thus it is quite far from a feasible device application, which demands a reversible operation. Here we use angle-resolved photoemission spectroscopy and spin- and angle-resolved photoemission spectroscopy to visualize the strain-driven band-structure evolution of the quasi-one-dimensional superconductor TaSe3. We demonstrate that it undergoes reversible strain-induced topological phase transitions from a strong topological insulator phase with spin-polarized, quasi-one-dimensional topological surface states, to topologically trivial semimetal and band insulating phases. The quasi-one-dimensional superconductor TaSe3 provides a suitable platform for engineering the topological spintronics, for example as an on/off switch for a spin current that is robust against impurity scattering.

Evidence for a higher-order topological insulator in a three-dimensional material built from van der Waals stacking of bismuth-halide chains.

Low-dimensional van der Waals materials have been extensively studied as a platform with which to generate quantum effects. Advancing this research, topological quantum materials with van der Waals structures are currently receiving a great deal of attention. Here, we use the concept of designing topological materials by the van der Waals stacking of quantum spin Hall insulators. Most interestingly, we find that a slight shift of inversion centre in the unit cell caused by a modification of stacking induces a transition from a trivial insulator to a higher-order topological insulator. Based on this, we present angle-resolved photoemission spectroscopy results showing that the real three-dimensional material Bi4Br4 is a higher-order topological insulator. Our demonstration that various topological states can be selected by stacking chains differently, combined with the advantages of van der Waals materials, offers a playground for engineering topologically non-trivial edge states towards future spintronics applications.

[Tricuspid Valve Ring Annuloplasty with Posterior Annular Plication for Functional Tricuspid Regurgitation].

This report presents a modified procedure of tricuspid valve ring annuloplasty (R-TAP) with posterior annular plication for functional tricuspid regurgitation (TR). Sutures on the native annulus were placed by a standard fashion in R-TAP, and those on the posterior annulus and its bilateral commissures were passed through in a narrow range between the 3 and 4 o'clock positions of the 26-mm ring. The other sutures were done with an usual manner and the ring was fixed to the annulus, resulting in the posterior annular plication( bicuspidization). Follow-up was performed for more than 5 years( mean: 7.9 years, range:5.5~11.5 years) by echocardiography in 13 cases. Postoperative TR reduced significantly to less than moderate, which was maintained during the entire follow-up period, even in the case with atrial fibrillation. There was no sign of tricuspid stenosis. R-TAP with posterior annular plication was feasible, reproducible, and effective, although further investigation is needed.

[Preservation of the Spinal Perfusion Artery during Descending Thoracic and Thoracoabdominal Aortic Surgery].

This is a 3-case report of successful descending thoracic and thoracoabdominal aortic surgery by preserving the spinal perfusion artery (SPA) identified preoperatively. In Case 1, an 85-year-old woman, computed tomography (CT) showed Crawford type Ⅴ thoracoabdominal aortic aneurysm (TAAA:60 mm) and a SPA originated from L2. In Case 2, a 76-year-old man, CT revealed type Ⅳ TAAA( 58 mm) and a SPA originated from Th11. In Case 3, a 74-year-old man, CT detected an infectious pseudoaneurysm(44 mm) in the descending thoracic aorta with 2 SPAs originating from Th10 and L2. The ranges of graft replacement were Th7-Th12, Th12-L4, and Th8-Th10, respectively, while preserving all SPAs. All patients recovered well without postoperative neurological deficits. Although the protective effect of the SPA preservation against the spinal cord ischemia is still controversial, preoperative identification of the SPA was useful for planning a surgical strategy for descending thoracic and thoracoabdominal aortic repair surgery.

[Graft Harvesting for Coronary Artery Bypass Grafting].

In coronary artery bypass grafting, graft harvesting is a fundamental and important technique of cardiovascular surgeons. Young cardiovascular surgeons typically experience graft harvesting for the first time early in their training. While several methods for graft harvesting have been developed in recent years with the goal of improving graft patency and reducing surgical invasiveness, the conventional and basic procedures remain important and are performed widely in cardiovascular institutions throughout Japan. Becoming familiarized with these basic graft harvest procedures is considered extremely important and useful for young cardiovascular surgeons. In this chapter, we discuss the basic methods of harvesting grafts of the internal thoracic artery, radial artery, gastroepiploic artery, and saphenous vein.

[Mitral Valve Replacement with the On-X Valve].

This is a 3-case report of mitral valve replacement (MVR) with an On-X mechanical valve followed up to 10 years. Case 1(64-year-old man) and case 2 (66-year-old woman) experienced traffic accident and traumatic event, respectively, in their chronic phase after MVR. Case 1 had multiple bone fractures of the bilateral lower limbs, which was followed by systemic infection and pyogenic spondylitis. He needed long-term antibiotics therapy for more than 4 years. Case 2 fell down at home and severely hit her head, which resulted in a traumatic subarachnoid hemorrhage. She was in a deep coma, and needed discontinuation of anticoagulation therapy for 4 weeks. Case1, 2, and 3(54-year-old man) are doing well in New York Heart Association functional class I without any valve-related thromboembolic or hemorrhagic events at 10, 9 and 8 years after MVR, respectively. On-X valve performance has also been found well maintained in all cases by echocardiography, even after traumatic accident or discontinuation of anticoagulation in Case 1 and 2. In this report, the On-X mechanical valve demonstrated good midterm result of its valve performance in the mitral position and its potential advantages in antithrombogenicity.

[Concurrent Mitral and Tricuspid Valve Surgery in a Patient with Left Collapsed Lung;Report of a Case].

A 77-year-old man was referred to our hospital with severe mitral valve regurgitation. Secondary to left partial lobectomy for tuberculosis 55 years earlier, his mediastinum was shifted to the left, and his pulmonary function was moderately decreased. Mitral valve replacement and tricuspid annuloplasty were performed with a median sternotomy. Although the heart was shifted to the left, the mitral valve was easily visualized when the right side of the pericardium was extensively elevated. The tracheal intubation tube was removed 1 day after the operation. The patient's postoperative course was uneventful, and he was discharged on the 13th postoperative day. We describe our surgical strategy in this patient with a literature review.

[Intraoperative Endoscopic Evaluation of the Aortic Valve in Aortic Valve Repair].

This report discusses intraoperative endoscopic evaluation of the aortic valve performed in 2 cases of aortic valve repair. The "direct" or real image by the endoscopy helped to confirm the preoperatively-known lesion and even to detect a new legion which was not detected preoperatively. The endoscopy also enabled the evaluation of the aortic valve under the pressure-loaded condition without releasing the aortic clamp. Postoperative aortic regurgitation was grade I or less in both cases, although it progressed to grade II at 1 year in case 2. Echocardiographic parameters demonstrated no change in the size of the aortic root configuration for 8 and 5 years in case 1 and case 2, respectively. Intraoperative aortic endoscopy was useful to define the pathogenesis of aortic regurgitation and to evaluate the cusp repair procedures, which may contribute to a good mid-term result of aortic valve repair.

[Primary cardiac leiomyosarcoma originating from the left atrium].

Primary malignant cardiac tumors occur extremely rarely. Among these, leiomyosarcomas are exceptionally rare. We described a case of left atrial leiomyosarcoma in which surgical intervention was followed by adjuvant radiation therapy. A 74-year-old male was admitted for dyspnea. Chest X-ray showed severe pulmonary congestion. Echocardiography revealed large tumor in the left atrium. Emergency operation was performed. The tumor invaded the left atrial wall and the mitral valve, and the lesion was resected as extensively as possible. Postoperative pathologic examination confirmed leiomyosarcoma. He underwent adjuvant radiotherapy postoperatively. However, early local recurrence was recognized. He died due to sudden circulatory collapse in 8th postoperative month. As cardiac leiomyosarcomas have extremely poor prognosis, complete resection and effective postoperative adjuvant therapy are necessary.

Caloforines A-G, coumarins from the bark of Calophyllum scriblitifolium.

Bioactivity-guided separation of the methanol extract of Calophyllum scriblitifolium bark led to the isolation of five new pyranocoumarins, caloforines A-E (1-5) and two new coumarins, caloforines F and G (6 and 7). Their structures were elucidated by 1D and 2D NMR spectroscopy, and their absolute configurations were investigated by a combination of CD spectroscopy and DFT calculation. Caloforines A-F (1-6) showed moderate antimalarial activity against Plasmodium falciparum 3D7 strain.

Structure-based prediction of the IgE epitopes of the major dog allergen Can f 1.

Allergy to dogs has become increasingly prominent worldwide. Seven dog allergens have been identified, including Canis familiaris allergen 1-7 (Can f 1-7). Although Can f 1 is a major dog allergen sensitized to 50-75% of dog-allergic subjects, its IgE epitopes have not been identified. The structural analysis of an allergen is important to identify conformational epitopes. In this study, we generated a recombinant Can f 1 protein and determined its crystal structure using X-ray crystallography. Can f 1 had a typical lipocalin fold, which is composed of an eight-stranded ß-barrel and α-helix, and has high similarity to Can f 2, Can f 4, and Can f 6 in overall structure. However, the localizations of surface charges on these proteins were quite different. Based on sequence alignment and tertiary structure, we predicted five critical residues (His86, Glu98, Arg111, Glu138, and Arg152) for the IgE epitopes. The relevance of these residues to IgE reactivity was assessed by generating Can f 1 mutants with these residues substituted for alanine. Although the effects of the mutation on IgE binding depended on the sera of dog-allergic patients, H86A and R152A mutants showed reduced IgE reactivity compared with wild-type Can f 1. These results suggest that Can f 1 residues His86 and Arg152 are candidates for the IgE conformational epitope.

[Mitral valve replacement in a patient with multiple myeloma].

We herein report a case of a 71-year-old male with untreated multiple myeloma (MM) and congestive heart failure due to moderate mitaral regurgitation, who successfully underwent mitral valve replacement and tricuspid annuloplasty. MM has various complications such as bleeding tendency, anemia, renal dysfunction, hyperviscosity syndrome, and susceptibility to bacterial infection. Considering bleeding tendency and post-operative anti-coagulant therapy, a bioprosthesis was chosen in this case. The postoperative course was uneventful. When cardiac surgery is indicated in patients with MM, we must carefully consider and manage the specific perioperative problems and indications for cardiac procedures.

Observation and control of the weak topological insulator state in ZrTe5.

A quantum spin Hall (QSH) insulator hosts topological states at the one-dimensional (1D) edge, along which backscattering by nonmagnetic impurities is strictly prohibited. Its 3D analogue, a weak topological insulator (WTI), possesses similar quasi-1D topological states confined at side surfaces. The enhanced confinement could provide a route for dissipationless current and better advantages for applications relative to strong topological insulators (STIs). However, the topological side surface is usually not cleavable and is thus hard to observe. Here, we visualize the topological states of the WTI candidate ZrTe5 by spin and angle-resolved photoemission spectroscopy (ARPES): a quasi-1D band with spin-momentum locking was revealed on the side surface. We further demonstrate that the bulk band gap is controlled by external strain, realizing a more stable WTI state or an ideal Dirac semimetal (DS) state. The highly directional spin-current and the tunable band gap in ZrTe5 will provide an excellent platform for applications.

Observation of small Fermi pockets protected by clean CuO2 sheets of a high-T c superconductor.

In cuprate superconductors with high critical transition temperature (T c), light hole-doping to the parent compound, which is an antiferromagnetic Mott insulator, has been predicted to lead to the formation of small Fermi pockets. These pockets, however, have not been observed. Here, we investigate the electronic structure of the five-layered Ba2Ca4Cu5O10(F,O)2, which has inner copper oxide (CuO2) planes with extremely low disorder, and find small Fermi pockets centered at (π/2, π/2) of the Brillouin zone by angle-resolved photoemission spectroscopy and quantum oscillation measurements. The d-wave superconducting gap opens along the pocket, revealing the coexistence between superconductivity and antiferromagnetic ordering in the same CuO2 sheet. These data further indicate that superconductivity can occur without contribution from the antinodal region around (π, 0), which is shared by other competing excitations.

Experimental Methods for Spin- and Angle-Resolved Photoemission Spectroscopy Combined with Polarization-Variable Laser.

The goal of this protocol is to present how to perform spin- and angle-resolved photoemission spectroscopy combined with polarization-variable 7-eV laser (laser-SARPES), and demonstrate a power of this technique for studying solid state physics. Laser-SARPES achieves two great capabilities. Firstly, by examining orbital selection rule of linearly polarized lasers, orbital selective excitation can be carried out in SAPRES experiment. Secondly, the technique can show full information of a variation of the spin quantum axis as a function of the light polarization. To demonstrate the power of the collaboration of these capabilities in laser-SARPES, we apply this technique for the investigations of spin-orbit coupled surface states of Bi2Se3. This technique affords to decompose spin and orbital components from the spin-orbit coupled wavefunctions. Moreover, as a representative advantage of using the direct spin detection collaborated with the polarization-variable laser, the technique unambiguously visualizes the light polarization dependence of the spin quantum axis in three-dimension. Laser-SARPES dramatically increases a capability of photoemission technique.