The p38 mitogen-activated protein kinase is involved in stress-induced phospholipase D activation in vascular smooth muscle cells

Oxidative stress has been implicated in mediation of vascular disorders. Earlier study showed that the exposure of vascular smooth muscle cells (VSMC) to pervanadate (hydrogen peroxide plus orthovanadate) resulted in the accumulation of [3H]phosphatidylbutanol. In this study, the effect of pervanadate on the activation of p38 mitogen-activated protein kinase (p38 MAPK) was studied in the VSMC. Pervanadate treatment activated p38 MAPK in a dose-and time-dependent manner. Interestingly, specific inhibition of p38 MAPK with SB203580 attenuated pervanadate-induced PLD activation. This correlates with the finding that expression of dominant negative mutants of MKK3/6 inhibited the PLD activation. SB203580 pretreatment also inhibited other cellular stressors (i.e. high osmolarity and UV light)-induced PLD activation. The possible correlationship of p38 MAPK activation with PKC was examined since PKC is reported to be involved in the pervanadate-induced PLD activation. Calphostin C, a PKC inhibitor, suppressed pervanadate-induced p38 MAPK and PLD activation in a dose-dependent manner. These results suggest that PKC-p38 MAPK may represent an upstream pathway of PLD in the signal transduction of cellular stress.     

Ring‐Opening Reactions of 3‐Aryl‐1‐benzylaziridine‐2‐carboxylates and Application to the Asymmetric Synthesis of an Amphetamine‐Type Compound

Nucleophilic ring‐opening reactions of 3‐aryl‐1‐benzylaziridine‐2‐carboxylates were examined by using O‐nucleophiles and aromatic C‐nucleophiles. The stereospecificity was found to depend on substrates and conditions used. Configuration inversion at C(3) was observed with O‐nucleophiles as a major reaction path in the ring‐opening reactions of aziridines carrying an electron‐poor aromatic moiety, whereas mixtures containing preferentially the syn‐diastereoisomer were generally obtained when electron‐rich aziridines were used (Tables 1–3). In the reactions of electron‐rich aziridines with C‐nucleophiles, S_N2 reactions yielding anti‐type products were observed (Table 4). Reductive ring‐opening reaction by catalytic hydrogenation of (+)‐trans‐(2S,3R)‐3‐(1,3‐benzodioxol‐5‐yl)aziridine‐2‐carboxylate (+)‐trans‐ 3c afforded the corresponding α‐amino acid derivative, which was smoothly transformed into (+)‐tert‐butyl [(1R)‐2‐(1,3‐benzodioxol‐5‐yl)‐1‐methylethyl]carbamate((+)‐ 14 ) with high retention of optical purity (Scheme 6).     

New tetradentate Schiff-base polymers: preparation of poly[2,5-(didodecyloxy)phenylene-1,4-diyl-alt-N,N-(o-phenylene)-bis(salicylideneiminato-4,4-diyl)] and poly[2,5-(didodecyloxy)phenylene-1,4-diyl-alt-N,N-(alkylidene)-bis(salicylideneiminato-4,4-diyl)]s

New tetradentate Schiff-base polymers, in which phenylene units alternate with salicylideneiminato units, have been prepared by condensation of 2,5-(didodecyloxy)-1,4-bis(3-formyl-4-hydroxyphenyl)benzene (DFHB) with appropriate diamines in a mixed solution of CHCl₃/toluene/acetic acid with 31-79% yields. DFHB as the key building block was prepared by the Suzuki reaction of 2,5-(didodecyloxy)benzene-1,4-diboronic acid with 5-bromosalicylaldehyde in a two-phase solution of tetrahydrofuran/water in the presence of NaHCO₃/Pd(PPh₃)₄ in 45% yield. The molecular structures of the prepared compounds were identified by spectroscopy. Their absorption spectroscopic profiles have been analyzed.     

On an elaboration of M. Kac's theorem concerning eigenvalues of the Laplacian in a region with randomly distributed small obstacles

We removem-balls of centersw ₁,...,w _m with the same radius α/m from a bounded domain Ω inR ³ with smooth boundary γ. Let μ _k (α/m;w(m)) denote thek-th eigenvalue of the Laplacian in Ω/m-balls under the Dirichlet condition. We consider μ _k (α/m;w(m)) as a random variable on a probability space (w ₁,...,w _m)∈Ω × ... × Ω and we examine a precise behaviour of μ _k (α/m;w(m)) asm → ∞. We give an elaboration of. M. Kac's theorem.     

Induction of nitric oxide synthase (NOS) by soluble glucocorticoid induced tumor necrosis factor receptor (sGITR) is modulated by IFN-gamma in murine macrophage

Earlier study showed that glucocorticoid induced tumor necrosis factor receptor (GITR), a new TNFR family, activated murine macrophages to express inducible nitric oxide synthase (iNOS) and to generate nitric oxide (NO). A possible involvement of pro-inflammatory cytokines on NO production by GITR was investigated in vitro systems and signaling molecules contributing to sGITR-induced iNOS production are determined in Raw 264.7 cells, a murine macrophage cell line. The result showed that the synergy was afforded by the combination of GITR with IFN-g in a dose-dependent manner but IFN-gamma alone was not able to induce NOS. No effects were observed with TNF-alpha, IL-1beta, or IL-6 co-treated with GITR. To determine signaling molecules contributing to sGITR-induced iNOS production, a specific inhibitor for signal pathway proteins tested showed that PDTC (NF-kappaB) and genistein (tyrosine kinase) inhibited NOS induction significantly, while sodium orthovanadate (tyrosine phosphatase) potentiated NOS expression. These results suggest that activations of NF-kappaB were involved in induction of iNOS by GITR and IFN-gamma priming caused earlier and stronger NF-kappaB activation.     

Isolation of a potent anti-MRSA sesquiterpenoid quinone from Ulmus davidiana var. japonica

A highly potent anti-MRSA sesquiterpenoid has been isolated from Ulmus davidiana var. japonica, which has been traditionally used to treat infectious diseases in Korea. This naturally occurring antibiotic was identified as mansonone F (1). This compound has been found to be highly active specifically against MRSA and showed an MIC range of 0.39-3.13 microg/ml which is comparable to that of vancomycin.     

Efficient chemoselective deprotection of silyl ethers using catalytic 1-chloroethyl chloroformate in methanol

Fast and chemoselective desilylation of silyl-protected alcohols was achieved using a catalytic amount of 1-chloroethyl chloroformate in methanol. With a minimal amount of 1-chloroethyl chloroformate as the source for anhydrous HCl, extremely efficient cleavage of silyl ethers of primary and secondary alcohols was accomplished, and chemoselective deprotection of one silyl ether in the presence of another silyl or other acid-labile group was possible through controlling the amount of the chloroformate and reaction time.     

Facile syntheses of 3-spiro- and 3,6-bridged 2,5-piperazinediones

The intramolecular addition of hydroxyl group of 3-(3-hydroxyl)propylidene-2,5-piperazinedione to 3-position and the same substitution of 3-(3-hydroxy)propyl derivative to 6-position gave the corresponding 3-spiro- and 3,6-bridged 2,5-piperazinediones, respectively.     

Self-assemblies of new rigid angular ligands and metal centers toward the rational construction and modification of novel coordination polymer networks

Self-assemblies of rigid angular ligands with 120 degrees molecular angle and metal centers have been investigated with the aim of achieving the rational construction and modification of coordination polymer structures. The reactions of Co(NCS)(2) with 1,3-bis(trans-4-styrylpyridyl)benzene (L(1)()), 2,6-bis(trans-4-styrylpyridyl)pyridine (L(2)()), 1,3-bis(trans-4-styrylpyrimidyl)benzene (L(3)()), and 1,3-bis(trans-4-styrylquinoly)benzene (L(4)()) afford complexes [Co(L(1)())(2)(NCS)(2)]( infinity ) (1), [Co(L(2)())(2)(NCS)(2)]( infinity ) (2), Co(L(3)())(2)(NCS)(2)(CH(3)OH)(2) (3), and [Co(L(4)())(NCS)(2)]( infinity ) (4), respectively. The resulting complexes exhibit open framework, stairlike hydrogen-bonded chain and single-stranded helical coil structures, which are controlled by the variation of the geometry around the coordination site in ligands. Moreover, the coordination of L(1)() and L(2)() to Mn(hfac)(2) (hfac = 1,1,1,5,5,5-hexafluoroacetylacetonate) yields single-stranded helical coordination polymers of [Mn(L(1)())(hfac)(2)]( infinity ) (5) and [Mn(L(2)())(hfac)(2)]( infinity ) (6), respectively.     

Electronic structure and field emission of multiwalled carbon nanotubes depending on growth temperature

The electronic structure of multiwalled carbon nanotubes (CNTs) has been investigated, depending on the growth temperature, using synchrotron X-ray photoelectron spectroscopy (XPS) and field emission measurements. The vertically aligned CNTs are grown via pyrolysis of ferrocene and acetylene in a broad temperature range 600-1000 degrees C. The CNTs have a cylindrical structure with a uniform diameter of 20 nm. As growth temperature increases, due to an improved crystallinity of the graphitic sheets, the width of the XPS C 1s peak becomes narrower and the intensity of the valence band increases. Field emission from the as-grown CNTs exhibits a large enhancement of current density with growth temperature, strongly correlated with the electronic structure revealed by XPS.