Bisanthraquinone metabolites produced by the endophytic fungus Diaporthe sp

Two bisanthraquinones named (+)-epicytoskyrin (1) and (+)-1,1'-bislunatin (2) were produced by the endophytic fungus from a tea plant, which is a species closely related to Diaporthe phaseolorum strain sw-93-13. The chemical structures of the metabolites were elucidated on the basis of the physicochemical properties including the circular dichroism (CD) spectrum.     

Imaging findings of solitary fibrous tumor of the prostate: a case report

The imaging findings of a solitary fibrous tumor of the prostate are presented. A 35-year-old male presented with urinary retention and was found on transrectal ultrasonography to have a hypoechoic tumor of the prostate, measuring 5.5 cm in size. Magnetic resonance imaging on, the tumor showed low signal intensity on T1-weighted images and heterogeneous mixed signal intensity on T2-weighted images. Gadolinium-enhanced dynamic study showed gradual enhancement from the periphery to the center, and the enhancement is sustained. On immunohistochemistry, the spindle cells of the tumor showed positive staining for CD34 and bcl-2. Although the tumor was labeled as a low-grade malignancy on account of a low mitotic index (MIB-1 index) of about 5%, the patient developed local recurrence of the tumor with bladder wall invasion 12 months later.     

Loop coproducts in string topology and triviality of higher genus TQFT operations

Cohen and Godin constructed a positive boundary topological quantum field theory (TQFT) structure on the homology of free loop spaces of oriented closed smooth manifolds by associating certain operations called string operations to orientable surfaces with parametrized boundaries. We show that all TQFT string operations associated to surfaces of genus at least one vanish identically. This is a simple consequence of properties of the loop coproduct which will be discussed in detail. One interesting property is that the loop coproduct is nontrivial only on the degree d homology group of the connected component of LM consisting of contractible loops, where d=dimM, with values in the degree 0 homology group of constant loops. Thus the loop coproduct behaves in a dramatically simpler way than the loop product.     

Dihydropyrene annelated with dihydrothieno[3.4-b]pyrazine: synthesis and photoswitching property

In this study, 9,10-diacetoxyl-2,7-di-tert-butyl-trans-10b,10c-dimethyl-10b,10c-dihydropyrene annelated with a dihydrothieno[3.4-b]pyrazine unit (1a) was prepared, for the first time, from 5,13-di-tert-butyl-8,16-dimethyl-1,2,9,10-tetrahydroxy[2.2]metacyclophane and 3,4-diaminothiophene in two steps. The photoisomerization property of 1 was investigated by UV and ¹H NMR spectroscopies, and the quantitative isomerization between the more stable dihydropyrene (DHP) form and the less stable metacyclophane-diene (MCPD) form was observed. A thermally induced return reaction from the MCPD to the DHP form was examined at various temperatures, and the reaction rate was 0.0049 min⁻¹ at 45 °C, which is slower than that of the parent MCPD.     

New strategy for drastic enhancement of selectivity via chemical modification of counter anions in ionic liquid polymer phase

A new strategy for the design of a new chromatographic stationary phase via simple modifications of the counter anions in poly(ionic liquid)-grafted silica phase based on ionic self-assembly technology is proposed. The phase with methyl orange dye as counter anions exhibits ultra-high selectivity towards shape-constrained isomers.     

Synthesis of novel crownophanes containing two phenolic moieties via a tandem claisen rearrangement

A series of crownophanes containing two phenolic moieties within a macrocyclic ring have been successfully synthesized by a one-step thermal reaction from the corresponding macrocyclic polyethers by using a “Tandem Claisen Rearrangement”.     

Interference, fluctuation, and alternation of electron tunneling in protein media. 1. Two tunneling routes in photosynthetic reaction center alternate due to thermal fluctuation of protein conformation

Electron tunneling routes for the electron transfer from the bacteriopheophytin anion to the primary quinone in the bacterial photosynthetic reaction center of Rhodobactor sphaeroides are investigated by a combined method of molecular dynamics simulations for the protein conformation fluctuation and quantum chemical calculations for the electronic states of the donor, acceptor, and protein medium. The analysis of the tunneling route is made by mapping interatomic electron tunneling currents for each protein conformation. We found that there are two dominant routes mainly passing through Trp(M252) (Trp route) or mainly passing through Met(M218) (Met route). Actual electron tunneling pathways alternate between the two routes, depending on the protein conformation which varies with time. When either the Trp route or the Met route dominates, the electron tunneling matrix element /T(DA)/ becomes large. When both the Trp route and the Met route dominate, /T(DA)/ becomes very small due to the destructive interference of the electron tunneling currents between the two routes. We found that a linear relationship exists between the value of /T(DA)/ and the inverse of the degree of destructive interference Q for a wide range of values (ca. 3-10(3) for Q). A similar relationship was also found previously for electron transfer in ruthenium-modified azurins, suggesting that this relationship holds true in general. From these results, we are led to the conclusion that /T(DA)/ cannot exceed a maximum value at Q = 1, even if much variation of /T(DA)/ happens due to the fluctuation of protein conformation. We also conclude that the property of the electron transfer alternates between constructive and destructive interference, due to the fluctuation of protein conformation. It is impossible to keep a system in either constructive or destructive interference because thermal fluctuation of protein conformation takes place.     

Possible Mechanisms of Vascular Relaxation Induced by Pulsed-UV Laser

This study was designed to examine the mechanism of vasorelaxation induced by pulsed-UV laser. Luminal diameters of rat femoral arteries were measured prior to and following krypton-fluoride excimer laser irradiation of 248 nm in wavelength. The diameter was enlarged to 1.3 times the preirradiated size at 1 or 10 Hz irradiation when the fluence was over 2.0 mj/pulse/mm², while the diameter reached 1.8 times at 100 Hz with a fluence of 0.8 mj/pulse/mm². Vasorelaxation by the 100 Hz irradiation was inhibited when the artery was pretreated with methylene blue but was enhanced with superoxide dis-mutase. Pathological analysis revealed an ablation crater and vacuole formation in the vessel at 1 or 10 Hz irradiation, but these changes were not remarkable in the 100 Hz-exposed sample. These findings suggest that vasorelaxation induced by the pulsed UV irradiation at 1 or 10 Hz results from structural alteration of vascular smooth muscle by the ablation crater or vacuolization. On the other hand, a possible mechanism of vasorelaxation at the 100 Hz irradiation is partially related to nitric oxide.     

Photosensitized NADH formation system with multilayer TiO2 film

A TiO(2)/polymer film on a quartz plate fabricated by a layer-by-layer method was employed for NADH production from NAD(+) with lipoamide dehydrogenase and methyl viologen in Tris-HCl buffer on irradiation with UV light, and the ultra thin film prevented from enzyme deactivating effectively.