Nematic transition and highly two-dimensional superconductivity in BaTi2_2Bi2_2O revealed by 209^{209}Bi-nuclear magnetic resonance/nuclear quadrupole resonance measurements

In this Rapid Communication, a set of $^{209}$Bi-nuclear magnetic resonance (NMR)/nuclear quadrupole resonance (NQR) measurements has been performed to investigate the physical properties of superconducting (SC) BaTi$_2$Bi$_2$O from a microscopic point of view. The NMR and NQR spectra at 5~K can be reproduced with a non-zero in-plane anisotropic parameter $\eta$, indicating the breaking of the in-plane four-fold symmetry at the Bi site without any magnetic order, i.e., `the electronic nematic state'. In the SC state, the nuclear spin-lattice relaxation rate divided by temperature, $1/T_1T$, does not change even below $T_{\rm c}$, while a clear SC transition was observed with a diamagnetic signal. This observation can be attributed to the strong two-dimensionality in BaTi$_2$Bi$_2$O. Comparing the NMR/NQR results among BaTi$_2$$Pn$$_2$O ($Pn$ = As, Sb, and Bi), it was found that the normal and SC properties of BaTi$_2$Bi$_2$O were considerably different from those of BaTi$_2$Sb$_2$O and BaTi$_2$As$_2$O, which might explain the two-dome structure of $T_{\rm c}$ in this system.Comment: 5 pages, 6 figure

Structural characterization of a binuclear center of a Cu-containing NO reductase homologue from Roseobacter denitrificans: EPR and resonance Raman studies

AbstractAerobic phototrophic bacterium Roseobacter denitrificans has a nitric oxide reductase (NOR) homologue with cytochrome c oxidase (CcO) activity. It is composed of two subunits that are homologous with NorC and NorB, and contains heme c, heme b, and copper in a 1:2:1 stoichiometry. This enzyme has virtually no NOR activity. Electron paramagnetic resonance (EPR) spectra of the air-oxidized enzyme showed signals of two low-spin hemes at 15 K. The high-spin heme species having relatively low signal intensity indicated that major part of heme b3 is EPR-silent due to an antiferromagnetic coupling to an adjacent CuB forming a Fe–Cu binuclear center. Resonance Raman (RR) spectrum of the oxidized enzyme suggested that heme b3 is six-coordinate high-spin species and the other hemes are six-coordinate low-spin species. The RR spectrum of the reduced enzyme showed that all the ferrous hemes are six-coordinate low-spin species. ν(Fe–CO) and ν(C–O) stretching modes were observed at 523 and 1969 cm−1, respectively, for CO-bound enzyme. In spite of the similarity to NOR in the primary structure, the frequency of ν(Fe–CO) mode is close to those of aa3- and bo3-type oxidases rather than that of NOR

Asymmetrical membrane fluidity of bovine adrenal chromaffin cells and granules and effect of trichosporin-B-VIa

AbstractWe examined membrane fluidity of bovine adrenal chromaffin cells and chromaffin granules using cationic trimethylammonium derivative of diphenylhexatriene (TMA-DPH) as a fluorescence probe. After adding TMA-DPH to the suspension of chromaffin cells and that of granules, it first bound to the outer layer of the plasma membrane of the cells and that of the granule membrane, then gradually penetrated the inner layer of each membrane and distributed to both leaflets of the respective membranes. Accompanying increases in the ratio of incorporated probe on the cytoplasmic side of the chromaffin cell membrane, its fluorescence anisotropy gradually decreased. However, in chromaffin granules, the fluorescence anisotropy gradually increased with increases in the ratio of incorporated probe. These findings suggest that the inner layer of the plasma membrane and outer layer of the granular membrane are more fluid than the corresponding side of each membrane, which is suitable for the fusion between both membranes. We also examined the effect of trichosporin-B-VIa, a fungal ion channel forming α-aminoisobutyric acid-containing peptide, on the fluidity of chromaffin cells using TMA-DPH. The peptide decreased the fluorescence anisotropy and increased the fluorescence intensity in the concentration range that induced Ca2+ dependent catecholamine secretion, suggesting that a change in lipid dynamics of the lipid bilayer of the plasma membrane was induced by this peptide

Roles of MED1 in Quiescence of Hair Follicle Stem Cells and Maintenance of Normal Hair Cycling

MED1 (mediator complex subunit 1) is expressed by human epidermal keratinocytes and functions as a coactivator of several transcription factors. To elucidate the role of MED1 in keratinocytes, we established keratinocyte-specific Med1-null (Med1epi−/−) mice using the K5Cre/LoxP system. Development of the epidermis and appendages of Med1epi−/− mice were macroscopically and microscopically normal until the second catagen of the hair cycle. However, the hair cycle of Med1epi−/− mice was spontaneously repeated after the second telogen, which does not occur in wild-type (WT) mice. Hair follicles of Med1epi−/− mice could not enter anagen after 6 months of age, resulting in sparse pelage hair in older Med1epi−/− mice. Interfollicular epidermis (IFE) of Med1epi−/− mice was acanthotic and more proliferative than that of WT mice, whereas these findings were less evident in older Med1epi−/− mice. Flow cytometric analysis revealed that the numbers of hair follicle bulge stem cells were reduced in Med1epi−/− mice from a few months after birth. These results suggest that MED1 has roles in maintaining quiescence of keratinocytes and preventing depletion of the follicular stem cells

Bile duct adenocarcinoma with minor micropapillary component: a case report

Invasive micropapillary carcinoma (IMPC) is defined as a carcinoma composed of small clusters of tumor cells lying within clear spaces which simulate lymphovascular channels. This histologic pattern has been described in various organs, including the breast, lung, urinary bladder, ovary, stomach, pancreas, and major salivary glands. Although rarely observed as a pure histologic component, IMPC is usually mixed with conventional carcinoma, and is therefore often referred to as carcinoma with a micropapillary component. IMPCs are invariably associated with a high degree of aggressiveness, extensive lymphovascular invasion, extensive lymph node metastases, and poor prognosis. Here a case of bile duct adenocarcinoma with minor micropapillary component is described