High-throughput screening assay for the quantification of Cer d18:1/16:0, d18:1/24:0, d18:1/24:1, d18:1/18:0, d18:1/14:0, d18:1/20:0, and d18:1/22:0 in HepG2 cells using RapidFire mass spectrometry

Ceramides are known to be involved in various biological processes with their physiological levels elevated in various disease conditions such as diabetes, Alzheimer's, atherosclerosis. To facilitate the rapid screening of Cer d18:1/16:0, d18:1/24:0, d18:1/24:1, d18:1/18:0, d18:1/14:0, d18:1/20:0, and d18:1/22:0 inhibition in HepG2 cells, a RapidFire coupled to tandem mass spectrometry (RF–MS/MS) method has been developed. The RF platform provides an automated solid-phase extraction system that gave a throughput of 12.6 s per sample to an MS/MS system using electrospray ionization under the positive ion mode. Chromatographic separation of Cer d18:1/16:0, d18:1/24:0, d18:1/24:1, d18:1/18:0, d18:1/14:0, d18:1/20:0, and d18:1/22:0 was achieved using a ternary gradient on C₈ type E cartridge. The MS/MS ion transitions monitored were 538.2 → 264.2, 650.7 → 264.2, 648.6 → 264.2, 566.4 → 264.2, 510.4 → 264.2, 594.4 → 264.2, 622.5 → 264.2, and 552.3 → 250.2 for Cer d18:1/16:0, d18:1/24:0, d18:1/24:1, d18:1/18:0, d18:1/14:0, d18:1/20:0, d18:1/22:0, and the internal standard (Cer d17:1/18:0), respectively. The RF–MS/MS methodology showed an excellent performance with an average Z′ value of 0.5–0.7. This is the first report of an RF–MS/MS assay for screening of ceramides which is amenable for high-throughput screening.     

微量元素与癫痫(1)

癫痫是神经系统疾病中仅次于脑血管病的第二大病症。我国目前约有850万癫痫患者,每年新发40万人,给个人、家庭和社会带来了严重的负面影响。从癫痫流行病学、危险因素、微量元素失衡、微量元素再分布及微量元素脑影像学五个方面阐述了微量元素与癫痫的关系。     

A total synthesis of d,1-histrionicotoxin

The first total synthesis of d,1-histrionicotoxin (1) from the spirolactam (5) is reported.     

Synthesis and properties of isocyanate and isothiocyanate d1- and d2-complexes of vanadocene

The reactions of vanadocene and its halides Cp₂VCl and Cp₂VCl₂ with R₃MNCX (M  Sn, Si, X  O, S) and R₂M(NCX)₂ in various molar ratios have been studied. The reactions proceed either by an exchange of groups, with no change in the oxidation state of vanadium, or by an oxidative addition of pseudohalide ligand: V^II → V^III; V^III → V^IV. Oxidative addition results in the formation of (R₃M)₂ or gaseous hydrogen (in the reaction with HCl) in the reaction products.We have prepared the first ever monomeric and readily oxidisable d²-complexes of V^III of Cp₂VNCX-type and asymmetric d¹-complexes of Cp₂V(Cl)NCX type, which, although rather stable in air, undergo disproportionation into symmetric d¹-complexes on heating. In transmetallation reactions the ligand activity is found to increase in the order C1 < NCO < NCS. The complexes were characterised by GLC analysis, IR and ESR spectroscopy. A general scheme for the disproportionation reaction of asymmetric complexes of vanadocene is supported by differential thermal analysis data.     

Recherches sur les arǒmes. 16e communication [1]. Sur l'arǒme du cacao III

The isolation and analysis of a cocoa concentrate is described: 62 constituents have been identified, 42 of which for the first time. Most identifications are based upon mass spectrometry combined in many cases with IR. spectrometry, and comparison with reference compounds. A number of minor constituents could not be identified.     

Total synthesis of d,1-occidentalol by photoannelation

A nine step synthesis of an intermediate previously used in the synthesis of the sesquiterpene occidentalol is reported which incorporates a 2+2 photocycloaddition reaction as the key carbon carbon bond forming step.     

Pseudotetrahedral d(0), d(1), and d(2) metal-oxo cores within a tris(alkoxide) platform

Low-coordinate first-row metal complexes of d(0) [vanadium(V)], d(1) [chromium(V)], and d(2) [chromium(IV)] assume the unusual ligand field of a pseudotetrahedron when supported by a tripodal tBu(2)(Me)CO(-) alkoxide framework. Structural, spectroscopic, and reactivity studies, supported by density functional theory calculations, indicate that the d electrons in the chromium(V) and -(IV) oxo complexes reside in metal-oxygen antibonding orbitals, engendering disparate reactivity of the metal-oxo, depending on the number of d electrons present.     

Inelastic neutron scattering on a d1-d1-2 mixed-valence trimer cluster

We have carried out the calculations for inelastic neutron scattering spectra for thermal neutrons scattering on amixed-valence trimer d¹-d¹-d² cluster, and we have investigated the selection rules. The forbidden transitions include the A₁ A₂ transitions, independently of spin, as well as the¹A₂ ¹E transition. The rest of the transitions with S = 0, 1 are allowed, and in turn are subdivided according to intensity into strong and weak transitions. The scattering cross sections of the latter include the differences in the form factors of the mixedvalence ions (the indicated form factors are close) and are small in magnitude. The scattering cross sections and the line positions in the spectrum depend considerably on the tunneling and exchange parameters of the cluster.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 3, pp. 329–332, May–June, 1989.     

Recherches sur les arǒmes. 17e communication. Sur l'arǒme de framboise,IV

The neutral fraction of medium volatility from raspberry oil has been analysed by gas chromatography and mass spectrometry. From the large number of constituents thirtynine have been identified, 24 of them for the first time, including dihydro-β-ionone (I), epoxy-β-ionone (II), damascenone (III)¹, theaspirane (IV) and 2-hexen-4-olide (V). According to these results raspberry oil consists mainly of alcohols, ketones, aldehydes and lactones.