Ethanol-induced vasoconstriction is mediated via redox-sensitive cyclo-oxygenase-dependent mechanisms

The present study investigated the role of ROS (reactive oxygen species) and COX (cyclooxygenase) in ethanol-induced contraction and elevation of [Ca(2+)](i) (intracellular [Ca(2+)]). Vascular reactivity experiments, using standard muscle bath procedures, showed that ethanol (1-800 mmol/l) induced contraction in endothelium-intact (EC(50): 306 +/- 34 mmol/l) and endothelium-denuded (EC(50): 180 +/- 40 mmol/l) rat aortic rings. Endothelial removal enhanced ethanol-induced contraction. Preincubation of intact rings with L-NAME [N(G)-nitro-L-arginine methyl ester; non-selective NOS (NO synthase) inhibitor, 100 mu mol/l], 7-nitroindazole [selective nNOS (neuronal NOS) inhibitor, 100 mu mol/l], oxyhaemoglobin (NO scavenger, 10 mu mol/l) and ODQ (selective inhibitor of guanylate cyclase enzyme, 1 mu mol/l) increased ethanol-induced contraction. Tiron [O(2)(-) (superoxide anion) scavenger, 1 mmol/l] and catalase (H(2)O(2) scavenger, 300 units/ml) reduced ethanol-induced contraction to a similar extent in both endothelium-intact and denuded rings. Similarly, indomethacin (non-selective COX inhibitor, 10 mu mol/l), SC560 (selective COX- I inhibitor, 1 mu mol/l), AH6809 [PGF(2 alpha) (prostaglandin F(2 alpha))] receptor antagonist, 10 mu mol/l] or SQ29584 [PGH(2)(prostaglandin H(2))/TXA(2) (thromboxane A(2)) receptor antagonist, 3 mu mol/l] inhibited ethanol-induced contraction in aortic rings with and without intact endothelium. In cultured aortic VSMCs (vascular smooth muscle cells), ethanol stimulated generation of O(2)(-) and H(2)O(2). Ethanol induced a transient increase in [Ca(2+)](i), which was significantly inhibited in VSMCs pre-exposed to tiron or indomethacin. Our data suggest that ethanol induces vasoconstriction via redox-sensitive and COX-dependent pathways, probably through direct effects on ROS production and Ca(2+) signalling. These findings identify putative molecular mechanisms whereby ethanol, at high concentrations, influences vascular reactivity. Whether similar phenomena occur in vivo at lower concentrations of ethanol remains unclear.

Chemical similarities between Galactic bulge and local thick disk red giants: O, Na, Mg, Al, Si, Ca, and Ti

Context. The formation and evolution of the Galactic bulge and its relationship with the other Galactic populations is still poorly understood. Aims. To establish the chemical differences and similarities between the bulge and other stellar populations, we performed an elemental abundance analysis of alpha- (O, Mg, Si, Ca, and Ti) and Z-odd (Na and Al) elements of red giant stars in the bulge as well as of local thin disk, thick disk and halo giants. Methods. We use high-resolution optical spectra of 25 bulge giants in Baade's window and 55 comparison giants (4 halo, 29 thin disk and 22 thick disk giants) in the solar neighborhood. All stars have similar stellar parameters but cover a broad range in metallicity (-1.5 < [Fe/H] < +0.5). A standard 1D local thermodynamic equilibrium analysis using both Kurucz and MARCS models yielded the abundances of O, Na, Mg, Al, Si, Ca, Ti and Fe. Our homogeneous and differential analysis of the Galactic stellar populations ensured that systematic errors were minimized. Results. We confirm the well-established differences for [alpha/Fe] at a given metallicity between the local thin and thick disks. For all the elements investigated, we find no chemical distinction between the bulge and the local thick disk, in agreement with our previous study of C, N and O but in contrast to other groups relying on literature values for nearby disk dwarf stars. For -1.5 < [Fe/H] < -0.3 exactly the same trend is followed by both the bulge and thick disk stars, with a star-to-star scatter of only 0.03 dex. Furthermore, both populations share the location of the knee in the [alpha/Fe] vs. [Fe/H] diagram. It still remains to be confirmed that the local thick disk extends to super-solar metallicities as is the case for the bulge. These are the most stringent constraints to date on the chemical similarity of these stellar populations. Conclusions. Our findings suggest that the bulge and local thick disk stars experienced similar formation timescales, star formation rates and initial mass functions, confirming thus the main outcomes of our previous homogeneous analysis of [O/Fe] from infrared spectra for nearly the same sample. The identical a-enhancements of thick disk and bulge stars may reflect a rapid chemical evolution taking place before the bulge and thick disk structures we see today were formed, or it may reflect Galactic orbital migration of inner disk/bulge stars resulting in stars in the solar neighborhood with thick-disk kinematics.

Intracellular Ca(2+) Regulation During Neuronal Differentiation of Murine Embryonal Carcinoma and Mesenchymal Stem Cells

Changes in intracellular Ca(2+) concentration ([Ca(2+)](i)) play a central role in neuronal differentiation. However, Ca(2+) signaling in this process remains poorly understood and it is unknown whether embryonic and adult stem cells share the same signaling pathways. To clarify this issue, neuronal differentiation was analyzed in two cell lines: embryonic P19 carcinoma stem cells (CSCs) and adult murine bone-marrow mesenchymal stem cells (MSC). We studied Ca(2+) release from the endoplasmic reticulum via intracellular ryanodine-sensitive (RyR) and IP(3)-sensitive (IP(3)R) receptors. We observed that caffeine, a RyR agonist, induced a [Ca(2+)](i) response that increased throughout neuronal differentiation. We also demonstrated a functional coupling between RyRs and L-but not with N-, P-, or Q-type Ca(v)1 Ca(2+) channels, both in embryonal CSC and adult MSC. We also found that agonists of L-type channels and of RyRs increase neurogenesis and neuronal differentiation, while antagonists of these channels have the opposite effect. Thus, our data demonstrate that in both cell lines RyRs control internal Ca(2+) release following voltage-dependent Ca(2+) entry via L-type Ca(2+) channels. This study shows that both in embryonal CSC and adult MSC [Ca(2+)](i) is controlled by a common pathway, indicating that coupling of L-type Ca(2+) channels and RyRs may be a conserved mechanism necessary for neuronal differentiation.

Transport Barkhausen-like noise in uniaxially pressed Bi(1.65)Pb(0.35)Sr(2)Ca(2)Cu(3)O(10+delta) ceramic samples

We report on the detection of the transport Barkhausen-like noise (TBN) in polycrystalline samples of Bi(1.65)Pb(0.35)Sr(2)Ca(2) Cu(3)O(10+delta) (Bi-2223) which were subjected to different uniaxial compacting pressures. The transport Barkhausen-like noise was measured when the sample was subjected to an ac triangular-shape magnetic field (f similar to 1 Hz) with maximum amplitude B(max) approximate to 5.5 mT, in order to avoid the flux penetration within the superconducting grains. Analysis of the TBN signal, measured for several values of excitation current density, indicated that the applied magnetic field in which the noise signal first appears, B(a)(t(i)), is closely related to the magnetic-flux pinning capability of the material. The combined results are consistent with the existence of three different superconducting levels within the samples: (i) the superconducting grains; (ii) the superconducting clusters; and (iii) the weak-links. We finally argue that TBN measurements constitute a powerful tool for probing features of the intergranular transport properties in polycrystalline samples of high-T(c) superconductors. (C) 2010 Elsevier B.V. All rights reserved.

Experimental and theoretical study of transport properties in uniaxially pressed (Bi, Pb)(2)Sr(2)Ca(2)Cu(3)O(10+delta) ceramic samples

Experimental and theoretical studies on the magnetic field dependence of the electrical resistance R(B(a)) and the transport noise (TN) in polycrystalline high-T(c) superconductors subjected to different uniaxial compacting pressures were conducted. X-ray diffraction rocking curves were performed in different surfaces of the samples in order to investigated the degree of texture The results indicated an improvement of the degree of texture with increasing the uniaxial compacting pressure In theoretical simulations of the data, the polycrystalline superconductors were described as a series-parallel array of Josephson devices The intergranular magnetic field is described within the framework of the intragranular flux-trapping model and the distribution of the grain-boundary angles is assumed to follow the Rayleigh statistical function The proposed model describes well the experimental magnetoresistance R(B(a)) data We have found that the behavior of the R(B(a)) curves changes appreciably when different uniaxially compacting pressures are applied to the sample and such a changes are reproduced by the model when different grain-boundary angles distributions are used In addition, changes in the R(B(a)) dependence have their counterparts in the experimental transport noise signals (C) 2009 Elsevier B.V. All rights reserved

Impact of adenosine nucleotide translocase (ANT) proline isomerization on Ca(2+)-induced cysteine relative mobility/mitochondrial permeability transition pore

Mitochondrial membrane carriers containing proline and cysteine, such as adenine nucleotide translocase (ANT), are potential targets of cyclophilin D (CyP-D) and potential Ca(2+)-induced permeability transition pore (PTP) components or regulators; CyP-D, a mitochondrial peptidyl-prolyl cis-trans isomerase, is the probable target of the PTP inhibitor cyclosporine A (CsA). In the present study, the impact of proline isomerization (from trans to cis) on the mitochondrial membrane carriers containing proline and cysteine was addressed using ANT as model. For this purpose, two different approaches were used: (i) Molecular dynamic (MD) analysis of ANT-Cys(56) relative mobility and (ii) light scattering techniques employing rat liver isolated mitochondria to assess both Ca(2+)-induced ANT conformational change and mitochondrial swelling. ANT-Pro(61) isomerization increased ANT-Cys(56) relative mobility and, moreover, desensitized ANT to the prevention of this effect by ADP. In addition, Ca(2+) induced ANT ""c"" conformation and opened PTP; while the first effect was fully inhibited, the second was only attenuated by CsA or ADP. Atractyloside (ATR), in turn, stabilized Ca(2+)-induced ANT ""c"" conformation, rendering the ANT conformational change and PTP opening less sensitive to the inhibition by CsA or ADP. These results suggest that Ca(2+) induces the ANT ""c"" conformation, apparently associated with PTP opening, but requires the CyP-D peptidyl-prolyl cis-trans isomerase activity for sustaining both effects.

Ca(2+) binding to c-state of adenine nucleotide translocase (ANT)-surrounding cardiolipins enhances (ANT)-Cys(56) relative mobility: A computational-based mitochondrial permeability transition study

The oxidation of critical cysteines/related thiols of adenine nucleotide translocase (ANT) is believed to be an important event of the Ca(2+)-induced mitochondrial permeability transition (MPT), a process mediated by a cyclosporine A/ADP-sensitive permeability transition pores (PTP) opening. We addressed the ANT-Cys(56) relative mobility status resulting from the interaction of ANT/surrounding cardiolipins with Ca(2+) and/or ADP by means of computational chemistry analysis (Molecular Interaction Fields and Molecular Dynamics studies), supported by classic mitochondrial swelling assays. The following events were predicted: (i) Ca(2+) interacts preferentially with the ANT surrounding cardiolipins bound to the H4 helix of translocase, (ii) weakens the cardiolipins/ANT interactions and (iii) destabilizes the initial ANT-Cys(56) residue increasing its relative mobility. The binding of ADP that stabilizes the conformation ""m"" of ANT and/or cardiolipin, respectively to H5 and H4 helices, could stabilize their contacts with the short helix h56 that includes Cys(56), accounting for reducing its relative mobility. The results suggest that Ca(2+) binding to adenine nucleotide translocase (ANT)-surrounding cardiolipins in c-state of the translocase enhances (ANT)-Cys(56) relative mobility and that this may constitute a potential critical step of Ca(2+)-induced PTP opening. (C) 2009 Elsevier B.V. All rights reserved.

Reduced pH induces an inactive non-native conformation of the monomeric bothropstoxin-I (Lys49-PLA(2))

Bothropstoxin-I (BthTx-I), a Lys49-PLA(2) from Bothrops jararacussu venom, permeabilizes membranes by a non-hydrolytic Ca(2+)-independent mechanism. The BthTx-I showed activity against liposomes including 10% and 50% negatively charged lipids at pH 7.0, but not at pH 5.0. Nevertheless, ultracentrifugation and FRET demonstrated that at pH 5.0 the BthTx-I is bound to 50% negatively charged membranes. ANS binding identified a non-native monomeric conformation at pH 5.0, suggesting that tertiary structure alterations result in activity loss of the BthTx-I at low pH. (C) 2009 Elsevier Ltd. All rights reserved.

Collagen Type I, Collagen Type III, and Versican in Vocal Fold Lamina Propria

Objective: To analyze the distributions of collagen type I, collagen type III, and versican in the lamina propria of the human vocal fold. Design: Cross-sectional analysis of cadaveric vocal folds of adult human larynges. Setting: Academic tertiary referral center. Subjects: Larynges harvested at autopsy from 10 adult men and 10 adult women. Main Outcome Measures: Immunohistochemical reactions were performed using antihuman monoclonal antibodies to analyze the expression of collagen type I, collagen type III, and versican. Results: Collagen type I density was lower in the intermediate layer compared with the superficial and deep layers of vocal folds. Collagen type III density was lower in the intermediate layer compared with the deep layer. Versican density was lower in the superficial layer compared with the intermediate and deep layers. Versican density was lower in the lamina propria of women compared with men; this difference was noted in the superficial layer only. There was a positive correlation between collagen type III and versican densities within the lamina propria. Conclusion: Collagen type I, collagen type III, and versican are distributed differently within the lamina propria layers of the adult vocal folds.