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1.
Nature ; 584(7819): E4, 2020 Aug.
Article in English | MEDLINE | ID: mdl-32690939

ABSTRACT

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

2.
Nature ; 566(7745): 518-522, 2019 02.
Article in English | MEDLINE | ID: mdl-30742073

ABSTRACT

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.

3.
J Synchrotron Radiat ; 24(Pt 4): 836-841, 2017 Jul 01.
Article in English | MEDLINE | ID: mdl-28664891

ABSTRACT

A rotatable high-resolution angle-resolved photoemission spectroscopy (ARPES) system has been developed to utilize tunable linear-polarization geometries on the linear undulator beamline (BL-1) at Hiroshima Synchrotron Radiation Center. By rotating the whole ARPES measurement system, the photoelectron detection plane can be continuously changed from parallel to normal against the electric field vector of linearly polarized undulator radiation. This polarization tunability enables us to identify the symmetry of the initial electronic states with respect to the mirror planes, and to selectively observe the electronic states based on the dipole selection rule in the photoemission process. Specifications of the rotatable high-resolution ARPES system are described, as well as its capabilities with some representative experimental results.

4.
Osteoarthritis Cartilage ; 25(5): 727-736, 2017 05.
Article in English | MEDLINE | ID: mdl-27916560

ABSTRACT

OBJECTIVE: Moderate mechanical stress generated by normal joint loading and movement is essential for the maintenance of healthy articular cartilage. However, the effects of reduced loading caused by the absence of weight bearing or joint motion on articular cartilage and subchondral bone is still poorly understood. We aimed to characterize morphological and metabolic responses of articular cartilage and subchondral bone to decreased mechanical stress in vivo. METHODS: Mice were subjected to periods of hindlimb unloading by tail suspension or external fixation of the knee joints. The articular surface was observed with digital microscope and the epiphyseal bone was assessed by micro-CT analysis. Articular cartilage and subchondral bone were further evaluated by histomorphometric, histochemical, and immunohistochemical analyses. RESULTS: The joint surface was intact, but thickness of both the total and uncalcified layer of articular cartilage were decreased both after joint unloading and immobilization. Subchondral bone atrophy with concomitant marrow expansion predisposed osteoclast activity at bone surface to invade into cartilaginous layer. Uncalcified cartilage showed decreased aggrecan content and increased aggrecanase expression. Alkaline phosphatase (ALP) activity was increased at uncalcified cartilage, whereas decreased at calcified cartilage. The distributions of hypertrophic chondrocyte markers remained unchanged. CONCLUSION: Thinning of articular cartilage induced by mechanical unloading may be mediated by metabolic changes in chondrocytes, including accelerated aggrecan catabolism and exquisitely modulated matrix mineralization, and cartilage matrix degradation and resorption by subchondral osteoclasts. Cartilage degeneration without chondrocyte hypertrophy under unloading condition indicate the possible existence of mechanism which is different from osteoarthritis pathogenesis.


Subject(s)
Cartilage, Articular/pathology , Immobilization , Knee Joint/physiopathology , Stress, Mechanical , Analysis of Variance , Animals , Biopsy, Needle , Cartilage, Articular/physiopathology , Chondrocytes/ultrastructure , Disease Models, Animal , Immunohistochemistry , Knee Joint/pathology , Male , Mice , Mice, Inbred C57BL , Microscopy, Electron, Scanning/methods , Osteoarthritis/pathology , Osteoarthritis/physiopathology , Random Allocation , Reference Values , Sensitivity and Specificity
5.
Phys Rev Lett ; 118(9): 097002, 2017 Mar 03.
Article in English | MEDLINE | ID: mdl-28306267

ABSTRACT

We present angle-resolved photoemission spectroscopy measurements of the quasi-one-dimensional superconductor K_{2}Cr_{3}As_{3}. We find that the Fermi surface contains two Fermi surface sheets, with linearly dispersing bands not displaying any significant band renormalizations. The one-dimensional band dispersions display a suppression of spectral intensity approaching the Fermi level according to a linear power law, over an energy range of ∼200 meV. This is interpreted as a signature of Tomonoga-Luttinger liquid physics, which provides a new perspective on the possibly unconventional superconductivity in this family of compounds.

6.
Sci Rep ; 14(1): 127, 2024 Jan 04.
Article in English | MEDLINE | ID: mdl-38177136

ABSTRACT

We have developed a state-of-the-art apparatus for laser-based spin- and angle-resolved photoemission spectroscopy with micrometer spatial resolution (µ-SARPES). This equipment is realized by the combination of a high-resolution photoelectron spectrometer, a 6 eV laser with high photon flux that is focused down to a few micrometers, a high-precision sample stage control system, and a double very-low-energy-electron-diffraction spin detector. The setup achieves an energy resolution of 1.5 (5.5) meV without (with) the spin detection mode, compatible with a spatial resolution better than 10 µm. This enables us to probe both spatially-resolved electronic structures and vector information of spin polarization in three dimensions. The performance of µ-SARPES apparatus is demonstrated by presenting ARPES and SARPES results from topological insulators and Au photolithography patterns on a Si (001) substrate.

7.
Phys Rev Lett ; 109(6): 066404, 2012 Aug 10.
Article in English | MEDLINE | ID: mdl-23006289

ABSTRACT

We reveal a "high-energy anomaly" (HEA) in the band dispersion of the unconventional ruthenate superconductor Sr2RuO4, by means of high-resolution angle-resolved photoemission spectroscopy (ARPES) with tunable energy and polarization of incident photons. This observation provides another class of correlated materials exhibiting this anomaly beyond high-T(c) cuprates. We demonstrate that two distinct types of band renormalization associated with and without the HEA occur as a natural consequence of the energetics in the bandwidth and the energy scale of the HEA. Our results are well reproduced by a simple analytical form of the self-energy based on the Fermi-liquid theory, indicating that the HEA exists at a characteristic energy scale of the multielectron excitations. We propose that the HEA universally emerges if the systems have such a characteristic energy scale inside of the bandwidth.

8.
Phys Rev Lett ; 105(22): 226406, 2010 Nov 26.
Article in English | MEDLINE | ID: mdl-21231406

ABSTRACT

Using polarization- and hν-dependent angle-resolved photoemission spectroscopy, we uncovered the fine details of a quasiparticle's dynamics of a typical multiband superconductor, Sr2RuO4. We found strong hybridization between the in-plane and out-of-plane quasiparticles via the Coulomb and spin-orbit interactions. This effect enhances the quasiparticle mass due to the inflow of out-of-plane quasiparticles into the two-dimensional Fermi surface sheet, where the quasiparticles are further subjected to the multiple electron-boson interactions. We suggest that the spin-triplet p-wave superconductivity of Sr2RuO4 is phonon mediated.

9.
Phys Rev Lett ; 105(7): 076802, 2010 Aug 13.
Article in English | MEDLINE | ID: mdl-20868066

ABSTRACT

A hexagonal deformation of the Fermi surface of Bi2Se3 has been for the first time observed by angle-resolved photoemission spectroscopy. This is in contrast to the general belief that Bi2Se3 possesses an ideal Dirac cone. The hexagonal shape is found to disappear near the Dirac node, which would protect the surface state electrons from backscattering. It is also demonstrated that the Fermi energy of naturally electron-doped Bi2Se3 can be tuned by 1% Mg doping in order to realize the quantum topological transport.

10.
J Natl Cancer Inst ; 69(1): 95-101, 1982 Jul.
Article in English | MEDLINE | ID: mdl-6954327

ABSTRACT

In SD female rats sterilized by a single injection of testosterone propionate at 2 days after birth, the spontaneous occurrence of atypical hyperplasia and adenocarcinoma of the uterus was observed for a fairly long period (greater than 2 yr). Two atypical hyperplasias and 2 adenocarcinomas were detected in 25 androgen-sterilized rats (ASR) after 500 days of age; in contrast, in 111 normal control rats no abnormal uterine proliferation was detected during a 750-day observation period. These results indicate that a persistence of both hormone imbalances and dysfunctional uteri in ASR induces abnormal uterine proliferation at a late age.


Subject(s)
Adenocarcinoma/chemically induced , Sterilization, Reproductive , Testosterone , Uterine Neoplasms/chemically induced , Uterus/pathology , Animals , Body Weight , Female , Hyperplasia , Pregnancy , Rats , Rats, Inbred Strains , Uterus/drug effects
11.
Cancer Res ; 39(3): 1108-12, 1979 Mar.
Article in English | MEDLINE | ID: mdl-106957

ABSTRACT

When 7,12-dimethylbenz[a]anthracene-impregnated sutures were directly applied to the ovarian parenchyma of 8-week-old Sprague-Dawley rats (the clipping method), adenocarcinomas developed in 29 (39%) of the 75 rats during the 50-week observation period. When 20-methylcholanthrene was used, adenocarcinomas developed only in 1 (3%) of the 31 rats. Thus, the clipping method using 7,12-dimethylbenz[a]anthracene is satisfactory as an animal model of ovarian adenocarcinoma which comprises 85 to 90% of human malignant ovarian tumors. On the other hand, attempts were made to isolate cloned cell lines from these experimental ovarian adenocarcinomas in vitro, and two cloned cell lines were obtained. They were epithelioid and produced undifferentiated adenocarcinomas by back-transplantation into isologous newborn rats.


Subject(s)
9,10-Dimethyl-1,2-benzanthracene/administration & dosage , Adenocarcinoma/chemically induced , Benz(a)Anthracenes/administration & dosage , Ovarian Neoplasms/chemically induced , Adenocarcinoma/pathology , Animals , Cell Line , Female , Methylcholanthrene/administration & dosage , Neoplasm Transplantation , Neoplasms, Experimental/chemically induced , Ovarian Neoplasms/pathology , Rats , Transplantation, Isogeneic
12.
Endocrinology ; 133(1): 321-7, 1993 Jul.
Article in English | MEDLINE | ID: mdl-8319579

ABSTRACT

Spermiation, the process in which vertebrate spermatozoa are detached from investing Sertoli cells into the lumen of the seminiferous tubule, is a prerequisite for the successful fertilization. Using an in vitro Rana nigromaculata spermiation bioassay, we have shown that gonadotropin initiates spermiation by inducing the synthesis of delta 4-steroids by testis fragments. Among all of the delta 4-steroid metabolites produced by R. nigromaculata testis fragments, spermiation-inducing activity was confined to only one metabolite; this metabolite was identified as 17 alpha,20 alpha-dihydroxy-4-pregnen-3-one (17 alpha,20 alpha-DP). Induction of spermiation by gonadotropin in vitro was accompanied by marked elevations in 17 alpha,20 alpha-DP concentrations in incubation media. These findings provide evidence that 17 alpha,20 alpha-DP is the nautrally occurring spermiation-inducing hormone in R. nigromaculata.


Subject(s)
Hydroxyprogesterones/metabolism , Ranidae , Spermatogenesis/drug effects , 17-alpha-Hydroxyprogesterone , Animals , Biological Assay , Chorionic Gonadotropin/pharmacology , Cyanoketone/pharmacology , Hydroxyprogesterones/pharmacology , Male , Microscopy, Electron , Progesterone/metabolism , Testis/drug effects , Testis/metabolism
13.
FEBS Lett ; 375(1-2): 151-4, 1995 Nov 13.
Article in English | MEDLINE | ID: mdl-7498467

ABSTRACT

The endoplasmic streaming in Characean cells is an actin-dependent movement. The motor protein responsible for the streaming was partially purified and characterized. It was soluble at low ionic strength, an ATPase of a molecular mass of 225 kDa and activated more than 100 times by muscle F-actin. Surprisingly, in an in vitro motility assay, the motor protein moved muscle F-actin at 60 microns/s, which is similar to the velocity of streaming in a living cell and 10 times faster than muscle myosin. Proteolytic cleavage of actin impaired movement crucially on muscle myosin, but did not affect movement at all on the Chara motor protein, suggesting that the Chara motor protein would interact with actin via a set of sites different from those of muscle myosin.


Subject(s)
Actins/metabolism , Adenosine Triphosphatases/metabolism , Chlorophyta/physiology , Adenosine Triphosphatases/isolation & purification , Animals , Binding Sites , Electrophoresis, Polyacrylamide Gel , Endopeptidases/metabolism , Kinetics , Molecular Weight , Muscle, Skeletal/physiology
14.
Eur J Pharmacol ; 142(1): 133-6, 1987 Oct 06.
Article in English | MEDLINE | ID: mdl-3121362

ABSTRACT

Ultrasonic distress calls elicited in male rats by footshock under inescapable conditions were suppressed by diazepam. The suppression was blocked by pretreatment with Ro15-1788 or CGS8216, selective benzodiazepine receptor antagonists, while an opiate antagonist naloxone failed to modify the effect of diazepam. In contrast, naloxone antagonized but Ro15-1788 and CGS8216 did not antagonize beta-endorphin which also suppressed the ultrasonic vocalization. These findings suggest that benzodiazepine and opioid receptors may contribute separately to antianxiety activity.


Subject(s)
Diazepam/pharmacology , Endorphins/pharmacology , Vocalization, Animal/drug effects , Animals , Convulsants/pharmacology , Depression, Chemical , Flumazenil/pharmacology , Injections, Subcutaneous , Male , Pyrazoles/pharmacology , Rats , Rats, Inbred Strains , Ultrasonics
15.
Anat Embryol (Berl) ; 180(2): 165-73, 1989.
Article in English | MEDLINE | ID: mdl-2802180

ABSTRACT

Gonadal development in Rhacophorus arboreus, a sexually semidifferentiated type of tree frog, was observed by means of the electron microscope, and cell proliferation kinetics were examined autoradiographically. The genital ridge consisted of coelomic epithelial cells and primordial germ cells. The gonadal medulla was formed by the segregation of epithelial cells within the primordial gonad. Thereafter, the medullary cell mass was well developed and oogenesis began in the gonadal cortex, irrespective of genetic sex. During metamorphosis, the ovarian cavity was formed in the medullary mass. This ovarian structure developed further in females. In males, on the other hand, a layer of medullary cells comprising the epithelium of the ovarian cavity proliferated rapidly and reformed a large cell mass. The degeneration of ovarian follicles and the formation of cell cords (rudimentary seminiferous tubules) were seen in the cortex. These cell cords were separated from the superficial epithelium and continued to the medullary mass (rudimentary testicular rete). These results clearly indicate that both the cortical and medullary cells are derived from the coelomic epithelium and that the development of the cortex and medulla is not always antagonistic in the course of sexual differentiation.


Subject(s)
Gonads/embryology , Ranidae/embryology , Animals , Autoradiography , Female , Gonads/cytology , Male , Microscopy, Electron , Ovary/embryology , Sex Differentiation , Testis/embryology
16.
Carbohydr Res ; 230(1): 117-49, 1992 Jun 04.
Article in English | MEDLINE | ID: mdl-1511450

ABSTRACT

omega-(Methoxycarbonyl)alkyl glycopyranosides of D-mannose having C4, C7, C9, C12, and C15 carbon chains, L-fucose and 2-acetamido-2-deoxy-D-mannose having C7 and C9 carbon chains, D-xylose and 2-acetamido-2-deoxy-L-fucose having a C9 carbon chain, and 9-(methoxycarbonyl)-3,6-dioxanonyl glycopyranosides of D-mannose, 2-acetamido-2-deoxy-D-mannose, and L-fucose were synthesized as intermediates for coupling to human serum albumin in order to examine the effect of chain length and hydrophobicity of the spacer arm on the binding specificity of lectins. 8-(Methoxycarbonyl)octyl glycosides of beta-D-Man-(1----2)-alpha-D-Man, alpha-D-Man-(1----2)-alpha-D-Man, alpha-D-ManNAc-(1----2)-alpha-D-Man, beta-D-GlcNAc-(1----2)-alpha-D-Man, and their 6-O-positional isomers, beta-D-Man-(1----6)-alpha-D-Man, alpha-D-Man-(1----6)-alpha-D-Man, alpha-D-ManNAc-(1----6)-alpha-D-Man, and beta-D-GlcNAc-(1----6)-alpha-D-Man, were also synthesized.


Subject(s)
Carrier Proteins/chemical synthesis , Drug Carriers/chemistry , Glycosides/chemistry , Receptors, Cell Surface , Carbohydrate Sequence , Drug Carriers/chemical synthesis , Glycosides/chemical synthesis , Molecular Sequence Data
17.
J Antibiot (Tokyo) ; 35(12): 1665-9, 1982 Dec.
Article in English | MEDLINE | ID: mdl-6926749

ABSTRACT

The method for chemical modification of spergualin with retention of the configuration at the C-11 has been achieved by the use of tetrahydropyranyl group for protection of the 11-hydroxyl group. (-)-15-Deoxyspergualin (2), which shows about eight times stronger inhibition against mouse leukemia L-1210 than the natural (-)-spergualin(1), and (-)-spergualin-15-phosphate(3) possessing a good antitumor activity have been synthesized starting from 1.


Subject(s)
Antibiotics, Antineoplastic/chemical synthesis , Animals , Antibiotics, Antineoplastic/therapeutic use , Chemical Phenomena , Chemistry , Guanidines/chemical synthesis , Guanidines/pharmacology , Leukemia L1210/drug therapy , Mice
18.
Phys Rev E Stat Nonlin Soft Matter Phys ; 68(1 Pt 2): 016215, 2003 Jul.
Article in English | MEDLINE | ID: mdl-12935233

ABSTRACT

We experimentally demonstrate synchronization of chaos in one-way coupled He-Ne lasers with optical feedback. We observe different types of synchronization such as identical synchronization, inverse synchronization, and random amplification. These dynamics are maintained only for a short duration of several hundred milliseconds. We also observe generalized synchronization of chaos by using one master and two slave lasers. The generalized synchronization is achieved for a long duration of tens of seconds under injection locking. The generalized synchronization is always maintained while the injection locking is achieved.

19.
Drugs Exp Clin Res ; 21(1): 7-16, 1995.
Article in English | MEDLINE | ID: mdl-7796712

ABSTRACT

Antimicrobial activity of everninomicin (SCH) 27899) in comparison with two glycopeptides (vancomycin, teicoplanin) and six beta-lactam agents was evaluated against recent clinical isolates of Gram-positive bacteria. Everninomicin showed the highest activity against the species tested and MICs90% of everninomicin against Streptococcus pneumoniae, Streptococcus pyogenes, Enterococcus faecalis, Enterococcus faecium and Clostridium difficile were 0.1, 0.1, 0.2, 0.39, 0.1 microgram/ml, respectively. MICs90% of everninomicin against methicillin-resistant Staphylococcus aureus (MRSA) and Staphylococcus epidermidis (MRSE) were 0.78 microgram/ml. Laboratory induced resistance to everninomicin in strains of S. aureus and E. faecalis occurred in a stepwise manner and at a very slow rate. Post-antibiotic effect against strains of S. aureus and E. faecalis were 1.8 and 2.6 h, respectively, and a little longer than that of vancomycin. Adherence to glass surface of an MRSA strain was strongly repressed by the addition of sub MIC of everninomicin in combination with fosfomycin.


Subject(s)
Aminoglycosides , Anti-Bacterial Agents/pharmacology , Oligosaccharides/pharmacology , Bacterial Adhesion/drug effects , Drug Synergism , Gram-Positive Bacteria/drug effects , Microbial Sensitivity Tests
20.
Eur J Gynaecol Oncol ; 5(1): 16-20, 1984.
Article in English | MEDLINE | ID: mdl-6698049

ABSTRACT

Five cases of malignant change of ovarian dermoid cyst are presented. Two of these cases were of special interest due to the unusual nature of the malignancy. One case (an adenosquamous cell carcinoma) was apparently a malignant change of the columnar epithelium and its squamous metaplasia. The other case (a clear cell carcinoma) appeared to represent coincidental development of two tumors.


Subject(s)
Adenocarcinoma/pathology , Carcinoma, Squamous Cell/pathology , Dermoid Cyst/pathology , Neoplasms, Multiple Primary/pathology , Ovarian Neoplasms/pathology , Adult , Aged , Female , Humans , Middle Aged
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