Photonic crystal nanocavity with a Q factor exceeding eleven million.

Photonic crystal nanocavities that simultaneously possess small modal volumes and high quality (Q) factors have opened up novel research areas in photonics during this decade. Here, we present an important key for the increase of Q factors to ranges beyond ten million. A systematic investigation on photon lifetimes of air-bridge-type heterostructure nanocavities fabricated from silicon on insulator (SOI) substrates indicated the importance of cleaning the bottom side (buried oxide side) of the nanaocavites. Repeated thermal oxidation and an oxide removal process applied after the removal of the buried oxide layer underneath the nanocavities realized an experimental Q factor greater than eleven million, which is the highest experimental Q ever recorded. The results provide important information not only for Si PC nanocavities but also for general Si nanophotonic devices and photonic electronic convergence systems.

Syntheses of cytotoxic novel arctigenin derivatives bearing halogen and alkyl groups on aromatic rings.

The new lignano-9,9'-lactones (α,ß-dibenzyl-γ-butyrolactone lignans), which showed the higher cytotoxicity than arctigenin, were synthesized. The well-known cytotoxic arctigenin showed activity against HL-60 cells (EC50=12µM), however, it was inactive against HeLa cells (EC50>100µM). The synthesized (3,4-dichloro, 2'-butoxy)-derivative 55 and (3,4-dichloro, 4'-butyl)-derivative 66 bearing the lignano-9,9'-lactone structures showed the EC50 values of 10µM and 9.4µM against HL-60 cells, respectively. Against HeLa cells, the EC50 value of the derivative 66 was 27µM. By comparing the activities with the corresponding 9,9'-epoxy structure (tetrahydrofuran compounds), the importance of the lactone structure of 55 and 66 for the higher activities was shown. The substituents on the aromatic ring of the lignano-9,9'-lactones affected the cytotoxicity level, observing more than 10-fold difference.

Discovery of N-sulfonyl-7-azaindoline derivatives as potent, orally available and selective M(4) muscarinic acetylcholine receptor agonists.

We designed and synthesized novel N-sulfonyl-7-azaindoline derivatives as selective M4 muscarinic acetylcholine receptor agonists. Modification of the N-carbethoxy piperidine moiety of compound 2, an M4 muscarinic acetylcholine receptor (mAChR)-preferring agonist, led to compound 1, a selective M4 mAChR agonist. Compound 1 showed a highly selective M4 mAChR agonistic activity with weak hERG inhibition in vitro. A pharmacokinetic study of compound 1 in vivo revealed good bioavailability and brain penetration in rats. Compound 1 reversed methamphetamine-induced locomotor hyperactivity in rats (1-10 mg/kg, po).

[Comparison of hypersensitivity to branded and generic paclitaxel injections in rats].

The use of injectable generic antineoplastic agents has been increasing. Few studies have compared the quality and adverse reactions of generic and branded antineoplastic agents; and therefore, generic agents have not gained wide acceptance. Paclitaxel injections, which are used for treating solid cancers, are being marketed by some companies in Japan. The degree of hypersensitive reactions to these drugs may vary because of the differences in chemical properties of the polyoxyethylene castor oil that is used as a solvent in the paclitaxel preparations. Therefore, we investigated the incidence of pulmonary edema occurring as a hypersensitive reaction in rats administered branded and generic paclitaxel injections. Moreover, we compared the chemical properties of these preparations. We found that the pH of branded and generic paclitaxel preparations diluted with saline was different. This difference in pH may be attributed to a difference in chemical properties from the additive. We observed no significant differences in pulmonary vascular permeability, arterial partial pressure of oxygen, or leakage of protein in the pulmonary alveolus, between paclitaxel preparations administered to rats. These results suggest that both paclitaxel preparations induced pulmonary edema of a similar level in rats, irrespective of the differences in their chemical properties.

Antianxiety and antidepressant-like effects of AC-5216, a novel mitochondrial benzodiazepine receptor ligand.

We investigated the ability of N-benzyl-N-ethyl-2-(7,8-dihydro-7-methyl-8-oxo-2-phenyl-9H-purin-9-yl)acetamide (AC-5216), a novel mitochondrial benzodiazepine receptor (MBR) ligand, to produce anti-anxiety and antidepressant-like effects in various animal models. AC-5216 showed high affinity for MBRs prepared from rat whole brain (Ki 0.297 nm), rat glioma cells (IC50 3.04 nm) and human glioma cells (IC50 2.73 nm), but only negligible affinity for the other main receptors including central benzodiazepine receptors. AC-5216 produced anti-anxiety effects in the Vogel-type conflict test in rats, and in the light/dark box and social interaction tests in mice at 0.1-3, 0.003-0.01 and 0.01-0.3 mg kg(-1), p.o., respectively. These effects of AC-5216 were antagonized by PK11195, an MBR antagonist. In the forced swimming test in rats, AC-5216 (3-30 mg kg(-1), p.o.) reduced the immobility time, and this effect was blocked by PK11195. AC-5216 had no myorelaxant effects, did not affect the memory or prolong hexobarbitone-induced sleep in mice, even at doses as high as 1000 mg kg(-1), p.o. Although it did slightly prolong the ethanol-induced sleep time at 1000 mg kg(-1), AC-5216 (1-100 mg kg(-1), p.o.) produced no distinct change in the rat electroencephalogram. These results indicate that AC-5216 produces anti-anxiety and antidepressant-like effects that are mediated by MBR, but does not cause the side effects normally associated with conventional benzodiazepines. Hence, AC-5216 shows potential for the treatment of stress-related disorders including anxiety and depression.