Enhancement of Photoluminescence from Cu-doped β-FeSi2/Si Heterostructures

We have investigated photoluminescence (PL) behaviors of the Cu-doped β-FeSi2 thin film/Si heterostructure. Pronounced enhancement of an intrinsic A band and an impurity-related C band emissions has been observed in all the Cu-doped samples. The photo-carrier injection (PCI)-PL measurements have revealed that the PL enhancement is attributed to dynamic process of migration of holes where a repeated trap process of holes can be controlled by Cu-doping.International Conference and Summer School on Advanced Silicide Technology 2014, July 19–21, 2014, Tokyo, Japa

Characterization of Tight Junctions and Their Disruption by UVB in Human Epidermis and Cultured Keratinocytes

It has not been confirmed whether tight junctions (TJs) function as a paracellular permeability barrier in adult human skin. To clarify this issue, we performed a TJ permeability assay using human skin obtained from abdominal plastic surgery. Occludin, a marker protein of TJs, was expressed in the granular layer, in which a subcutaneously injected paracellular tracer, Sulfo-NHS-LC-Biotin (556.59Da), was halted. Incubation with ochratoxin A decreased the expression of claudin-4, an integral membrane protein of TJs, and the diffusion of paracellular tracer was no longer prevented at the TJs. These results demonstrate that human epidermis possesses TJs that function as an intercellular permeability barrier at least against small molecules (∼550Da). UVB irradiation of human skin xenografts and human skin equivalents (HSEs) resulted in functional deterioration of TJs. Immunocytochemical staining of cultured keratinocytes showed that occludin was localized into dot-like shapes and formed a discontinuous network when exposed to UVB irradiation. Furthermore, UVB irradiation downregulated the active forms of Rac1 and atypical protein kinase C, suggesting that their inactivation caused functional deterioration of TJs. In conclusion, TJs function as a paracellular barrier against small molecules (∼550Da) in human epidermis and are functionally deteriorated by UVB irradiation

New vasorelaxant indole alkaloids, villocarines A-D from Uncaria villosa.

Villocarines A–D (1–4), four new indole alkaloids have been isolated from the leaves of Uncaria villosa (Rubiaceae) and their structures were elucidated by 2D NMR methods and chemical correlations. Villocarine A (1) showed vasorelaxation activity against rat aortic ring and showed inhibition effect on vasocontraction of depolarized aorta with high concentration potassium, and also inhibition effect on phenylephrine (PE)-induced contraction in the presence of nicardipine in a Ca2+ concentration-dependent manner. The vasorelaxant effect by 1 might be attributed mainly to inhibition of calcium influx from extracellular space through voltage-dependent calcium channels (VDC) and/or receptor-operated Ca2+-channels (ROC), and also partly mediated through the increased release of NO from endothelial cells and opening of voltage-gated K+-channels

Tight junctions in Schwann cells of peripheral myelinated axons: a lesson from claudin-19–deficient mice

Tight junction (TJ)–like structures have been reported in Schwann cells, but their molecular composition and physiological function remain elusive. We found that claudin-19, a novel member of the claudin family (TJ adhesion molecules in epithelia), constituted these structures. Claudin-19–deficient mice were generated, and they exhibited behavioral abnormalities that could be attributed to peripheral nervous system deficits. Electrophysiological analyses showed that the claudin-19 deficiency affected the nerve conduction of peripheral myelinated fibers. Interestingly, the overall morphology of Schwann cells lacking claudin-19 expression appeared to be normal not only in the internodal region but also at the node of Ranvier, except that TJs completely disappeared, at least from the outer/inner mesaxons. These findings have indicated that, similar to epithelial cells, Schwann cells also bear claudin-based TJs, and they have also suggested that these TJs are not involved in the polarized morphogenesis but are involved in the electrophysiological “sealing” function of Schwann cells

Alkaloids from the seeds of Peganum harmala showing antiplasmodial and vasorelaxant activities

Bioassay-guided purification from the seeds of Peganum harmala led to the isolation of harmine (1), harmaline (2), vasicinone (3), and deoxyvasicinone (4). Harmine (1) and harmaline (2) showed a moderate in vitro antiplasmodial activity against Plasmodium falciparum. Quinazoline alkaloid, vasicinone (3), showed a vasorelaxant activity against phenylephrine-induced contraction of isolated rat aorta

Vasorelaxant activity of indole alkaloids from Tabernaemontana dichotoma.

The aim of this study was to search for bioactive natural products from medicinal plants targeting vasorelaxant activity and we found the methanol extract from bark of Tabernaemontana dichotoma showed vasorelaxant activity on rat aorta. We isolated eight indole alkaloids including 10-methoxyalstonerine (1), a new macroline type indole alkaloid, from bark of T. dichotoma. These were respectively identified as 10-methoxyaffinisine (2), lochnerine (3), cathafoline (4), (−)-alstonerine (5), 19,20-dehydro-10-methoxytalcarpine (6), alstonisine (7), and alstonal (8) based on spectroscopic analysis. Among them, sarpagine type (2 and 3), akuammiline type (4), and macroline oxindole type (7 and 8) showed potent vasorelaxant activity. Mechanism of action on vasorelaxant activity of 10-methoxyaffinisine (2), cathafoline (4), and alstonisine (7) was clarified. Effects of 10-methoxyaffinisine (2), cathafoline (4), and alstonisine (7) were partially mediated the NO release from endothelial cells. Furthermore, 10-methoxyaffinisine (2) and alstonisine (7) attribute to the inhibitory effect of VDC and ROC, and cathafoline (4) have inhibitory effect on Ca2+ influx via ROC. In addition, 10-methoxyaffinisine (2) as a major compound from bark of T. dichotoma showed hypotensive effect on normotensive rats in vivo

Alstiphyllanines I–O, ajmaline type alkaloids from Alstonia macrophylla showing vasorelaxant activity

Seven new ajmaline type alkaloids, alstiphyllanines I–O (1–7) were isolated from the leaves of Alstonia macrophylla together with six related alkaloids (8–13). Structures and stereochemistry of 1–7 were fully elucidated and characterized by 2D NMR analysis. A series of alstiphyllanines I–O (1–7) as well as the known ajmaline type alkaloids (8–13) showed that they relaxed phenylephrine (PE)-induced contractions against rat aortic ring. Among them, vincamedine (10) showed potent vasorelaxant activity, which may be mediated through inhibition of Ca2+ influx through voltage-dependent Ca2+ channels (VDCs) and/or receptor-operated Ca2+ channels (ROCs) as well as partially mediated the NO release from endothelial cells. The presence of substituents at both N-1 and C-17 may be important to show vasorelaxation activity