Akiko Saito

Upregulation of Nitric Oxide Production in Vascular Endothelial Cells by All-trans Retinoic Acid Through the Phosphoinositide 3-Kinase/Akt Pathway

Background—A natural retinoid all-trans retinoic acid (ATRA) contains various beneficial effects on vasculature, including suppression of neointima formation after balloon injury. However, little is known about the effects of ATRA on vascular endothelial function. We therefore studied its role in nitric oxide (NO) production of vascular endothelial cells (ECs). Methods and Results—Human dermal microvascular ECs, human umbilical vein ECs, and SV40-transformed rat lung vascular ECs were incubated with or without ATRA (1 &mgr;mol/L) for 48 hours. Their NO production was determined with the use of a fluorescent NO indicator, diaminofluorescein-2 diacetate. ATRA significantly increased their basal as well as acetylcholine-induced NO production. Treatment with N&ohgr;-nitro-l-arginine methyl ester or carboxy-PTIO suppressed their fluorescence. Increase of NO production was also observed by incubation with retinoic acid receptor (RAR) agonist Am580. ATRA-induced NO increase was abolished by coincubation with RAR antagonist LE540. Moreover, the NO increase was completely inhibited by the phosphoinositide 3-kinase (PI3K) inhibitor wortmannin and LY294002. ATRA as well as Am580 enhanced endothelial NO synthase (eNOS) phosphorylation at Ser-1177 as well as Akt phosphorylation at Ser-473 without changing their protein expression. Overexpression of dominant-negative Akt inhibited the eNOS phosphorylation. Moreover, ATRA increased PI3K activity as well as PI3K catalytic subunit p110β protein expression, which was completely inhibited by LE540 treatment. Real-time polymerase chain reaction analyses demonstrated that ATRA increased PI3K catalytic subunit p110β mRNA expression without affecting its stability. Finally, ATRA-induced NO increase was observed in COS-1 cells transfected with wild-type eNOS and RARα, but not with mutated eNOS whose Ser-1177 was substituted. Conclusions—ATRA increases NO production by eNOS phosphorylation through RAR-mediated PI3K/Akt pathway activation in vascular ECs and possibly plays beneficial roles in vascular endothelium. Retinoids may therefore be candidates as novel therapeutic agents against vascular disorders with endothelial damage.

Microbiological degradation of (-)-geosmin

One of the musty odour components in drinking water, (-)-geosmin was microbiologically degraded with the backwash water collected from a biological filter pilot plant at Lake Biwa (Japan) and activated sludge obtained from Sendai City Sewerage Bureau; in this process the presence of ethanol was essential for acceleration of the reaction. Four biodegradation products were detected by gas chromatography, among which a dehydration product and an oxidation product were identified by mass spectroscopic comparison with unambiguously synthesized authentic samples.

An efficient method for converting alcohols to azides with 2,4,4,6-tetrabromo-2,5-cyclohexadienone/PPh3/Zn(N3)2·2Py

Treatment of the salt generated from 2,4,4,6-tetrabromo-2,5-cyclohexadienone and PPh3 in a mixed solvent of CH3CNtoluene with primary and secondary alcohols in the presence of Zn(N3)2·2Py led to azides in excellent yields with inversion of configuration. Addition of hexamethylphosphorictriamide considerably accelerated the reaction.

Efficacy of sumatriptan in two pediatric cases with abdominal pain-related functional gastrointestinal disorders: does the mechanism overlap that of migraine?

We successfully treated 2 pediatric cases of abdominal pain-related functional gastrointestinal disorder with sumatriptan. When 9 years old, patient 1 developed periodic abdominal pain that was intractable to medication and remitted spontaneously. She was diagnosed with abdominal migraine, categorized as H2c in the Rome III criteria for functional gastrointestinal disorders. At age 12, intranasal sumatriptan relieved her pain, and her attacks halted 2 years later. Patient 2 was a 9-year-old girl diagnosed with attention-deficit hyperactivity disorder (ADHD), who began to have intermittent abdominal pain of variable severity, which sometimes restricted daily activity. She was diagnosed with childhood functional abdominal pain syndrome, categorized as H2d1 using the Rome III criteria. Intranasal sumatriptan also relieved her pain. These cases suggest that the mechanism of pain in abdominal pain-related functional gastrointestinal disorders is similar to that of migraine, with probable central hypersensitivity, at least in a subset of cases.

Stimulatory Effects of Low-Dose 3-Hydroxy-3-Methylglutaryl Coenzyme A Reductase Inhibitor Fluvastatin on Hepatocyte Growth Factor-Induced Angiogenesis: Involvement of p38 Mitogen-Activated Protein Kinase

Therapeutic angiogenesis has received much attention for its potential benefits in ischemic vascular disorders. Recently, the clinical application of hepatocyte growth factor (HGF) for therapeutic angiogenesis has become well known. Statins have also been reported to promote angiogenesis and ameliorate ischemic conditions. In the present study, we examined the effects of fluvastatin on HGF-induced angiogenesis using a human umbilical vein endothelial cell (HUVEC)/normal human dermal fibroblast (NHDF) co-culture system. The HGF-induced angiogenesis was augmented by fluvastatin at low dose, but it was decreased at high dose. Although fluvastatin increased vascular endothelial growth factor expression in NHDFs, it was observed only at a high dose. Low-dose fluvastatin decreased the HGF-induced p38 mitogen-activated protein kinase (MAPK) phosphorylation (Thr-180/Tyr-182) and HUVEC apoptosis in the presence of HGF. SB203580, a p38 MAPK inhibitor, ameliorated anisomycin (a p38 MAPK activator)-induced angiogenesis suppression in the presence of HGF. Moreover, the augmentation of the HGF-induced angiogenesis by fluvastatin was abrogated by the p38 MAPK inhibitors, SB203580, SB202190, and FR167653. High-dose fluvastatin decreased Akt phosphorylation (Ser-473) and HUVEC proliferation, and it increased p27kip1 in HUVECs. Interestingly, fluvastatin decreased the mRNA expression of integrins and tissue inhibitor of metalloproteinases (TIMPs) in HUVECs. Our data therefore indicate that the stimulatory effects of low-dose fluvastatin on the HGF-induced angiogenesis are mediated by its inhibitory effects on p38 MAPK phosphorylation induced by HGF, which may result in the suppression of EC apoptosis. High-dose fluvastatin inhibits Akt phosphorylation and HUVEC proliferation, and it increases p27kip1, which may result in its inhibitory effects on angiogenesis. In addition, integrins and TIMPs are candidates for angiogenesis regulation by fluvastatin.

A practical synthesis of enantiomerically pure (−)-geosmin via highly diastereoselective reduction of (4aS,8S)-4,4a,5,6,7,8-hexahydro-4a,8-dimethyl-2(3H)-naphthalenone

Abstract An asymmetric synthesis of (−)-geosmin 1via highly diastereoselective reduction of the enantiomerically pure title ketone 3 is described. Diisobutylaluminum hydride reduction of 3 in a mixed solvent of tetrahydrofuran and 1,2-dimethoxyethane led to allylic alcohol 4 in 96% d.e., which by recrystallization from hexane, afforded a diastereomerically pure sample. This was then converted to 1 in high overall yield through a five-step reaction sequence including a completely stereoselective epoxidation of silyl ether 6 and a one-pot process of epoxy silyl ether 7 to mesylate 9.

Lipase-catalyzed Asymmetric Synthesis of Enantiomerically Pure (2S,4aS,8S)-4a,8-Dimethyl-2,3,4,4a,5,6,7,8-octahydro-2-naphthalenol

Enantiomerically pure (2S,4aS,8S)-(+)-4a,8-dimethyl-2,3,4,4a,5,6,7,8-octahydro-2-naphthalenol (3), a key intermediate in the synthesis of natural geosmin (1), was prepared by enzymatic kinetic resolution. When racemic 3 was submitted to lipase (PS-30)-catalyzed asymmetric acetylation, employing vinyl acetate as the acyl donor, requisite product (+)-3 with a high enantiomeric excess was attained as the remaining alcohol. Recrystallization resulted in an enantiomerically pure sample.