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The potassium salts of the new S2N-heteroscorpionate ligand hydrobis(methimazolyl)(3,5-dimethylpyrazolyl)borate [HB(mt)2(pz3,5-Me)]−and its known analogue hydrobis(methimazolyl)(pyrazolyl)borate [HB(mt)2(pz)]−(prepared from KTp′ or KTp and methimazole, Hmt), and the adduct KTp·Hmt have polymeric structures in the solid state (the first a ladder and the other two chains). The iridaboratranes [IrHLL′{B(mt)2X}] (X = pz3,5-Meor pz), prepared from the heteroscorpionate anion and [{Ir(cod)(μ-Cl)}2] (LL′ = cod), subsequent carbonylation [LL′ = (CO)2] and then reaction with phosphine [LL′ = (CO)(PR3), R = Ph or Cy], have a pendant pyrazolyl ring and a bicyclo-[3.3.0] cage formed by an S2-bound B(mt)2fragment. The binuclear species [(cod)HIr{μ-B(mt)3}IrCl(cod)], the only isolated product of the reaction of KTm with [{Ir(cod)(μ-Cl)}2], also has an S2-bound iridaboratrane unit but with the third mt ring linked to square planar iridium(i). [ABSTRACT FROM AUTHOR]

The reaction of potassium hydrotris(methimazolyl)borate {KTm = HB(mt)3} with [{Rh(cod)(μ-Cl)}2] gave [Rh(cod)Tm] while the complexes [Rh(CO)(PR3)Tm] (R = Ph or NMe2) and [Rh{P(OPh)3}2Tm] were isolated from light-sensitive [Rh(CO)2Tm], prepared in situfrom KTm and [{Rh(CO)2(μ-Cl)}2], and PR3or P(OPh)3under CO. The complexes [Rh(cod)Tm] and [Rh(CO)(PR3)Tm] (R = Ph or NMe2) adopt κ3-S2Hstructures in the solid state but in all cases rapid dynamic exchange processes render the three mt rings equivalent in solution. Oxidation of [Rh(CO)(PPh3)Tm] with [Fe(η-C5H5)2][PF6] in the presence of NHPri2gave a mixture containing two monocationic rhodaboratranes. One is assigned as [Rh(CO)(PPh3){B(mt)3}][PF6] on the basis of IR and NMR spectroscopy, with boron transto the phosphine ligand. The second, structurally characterised as [Rh(PPh3){B(mt)3}][PF6], has boron transto an empty coordination site, vacated by CO. Similar oxidation of [Rh(cod)Tm] gave small quantities of the boron-fluorinated bis(scorpionate) [Rh{FB(mt)3}2][PF6]. [ABSTRACT FROM AUTHOR]

The essential amino acid leucine has been described to specifically activate signaling pathways leading to the activation of the translational machinery and the increase of total protein synthesis. Regulation of type I collagen production by hepatic stellate cells (HSC) is a multistep process involving transcriptional and post-transcriptional mechanisms. In the present work we studied the effect of leucine on translation regulation of collagen α1(I) production in HSC and the signaling pathways involved. Treatment of HSC with 5 mM leucine did not alter half-life or steady state levels of procollagen α1(I) mRNA, but caused an increase in procollagen α1(I) protein that correlated with changes of components involved in translational regulation, like enhanced 4E-BP1, Mnk-1, and eIF4E phosphorylation. Leucine also induced mTOR, ERK, and Akt phosphorylation in HSC, without affecting p38 and JNK activation. Pre-treatment of HSC with PD098059, wortmannin, or rapamycin prevented the profibrogenic action of leucine due to the inhibition of different molecular mechanisms. These results suggest leucine is a profibrogenic agent for HSC, activating signaling pathways that lead to an enhancement of collagen α1(I) production through translational regulation. J. Cell. Physiol. 209: 580–586, 2006. © 2006 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Abstract: Estrogens have been often identified as the major contributors to the endocrine-disrupting activity observed in environmental waters. However, their analysis in these, sometimes very complex, matrices is still challenging due to the very low detection limits and the selectivity required for their reliable determination at the very low concentrations at which they are physiologically active. In this work, a polyclonal enzyme-linked immunosorbent assay (ELISA) kit for 17-β-estradiol analysis, high-performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS) based on triple-quadrupole analyzer (QqQ), and a newly developed method based on ultra performance liquid chromatography–quadrupole time of flight mass spectrometry (UPLC–Q-TOF-MS) have been evaluated in terms of performance for the rapid screening, quantitative analysis, and unequivocal identification of some selected, environmentally relevant estrogens in different water matrices, including urban wastewater, river water, and ground water, after solid phase extraction. Compounds quantified and/or identified included the estrogens 17-β-estradiol, estrone, 17-α-ethynyl estradiol and estriol, and the isoflavones daidzein, genistein, and biochanin A. Except for a moderate overestimation using the ELISA kit, especially in the analysis of complex wastewater samples, results obtained by all the investigated techniques were in very good, general agreement. The instrumental sensitivity achieved increased in the order: UPLC–Q-TOF-MS