Differential antagonism by conotoxin p-TIA of contractions mediated by distinct alpha(1)-adrenoceptor subtypes in rat vas deferens, spleen and aorta

The ability of the conotoxin p-TIA, a 19-amino acid peptide isolated from the marine snail Conus tulipa, to antagonize contractions induced by noradrenaline through activation of alpha(1A)-adrenoceptors in rat vas deferens, alpha(1B)-adrenoceptors in rat spleen and alpha(ID)-adrenoceptors in rat aorta, and to inhibit the binding of [I-125]HEAT (2-[[beta-(4-hydroxyphenyl)ethyl]aminomethyl]-1-tetralone) to membranes of human embryonic kidney (HEK) 293 cells expressing each of the recombinant rat alpha(1)-adrenoceptors was investigated. p-TIA (100 nM to 1 muM) antagonized the contractions of vas deferens and aorta in response to noradrenaline without affecting maximal effects and with similar potencies (pA(2)similar to7.2, n=4). This suggests that p-TIA is a competitive antagonist of alpha(1A)- and alpha(1D)-adrenoceptors with no selectivity between these subtypes. Incubation of p-TIA (30 to 300 nM) with rat spleen caused a significant reduction of the maximal response to noradrenaline, suggesting that p-TIA is a non-competitive antagonist at alpha(1B)-adrenoceptors. After receptor inactivation with phenoxybenzamine, the potency of p-TIA in inhibiting contractions was examined with similar occupancies (similar to25%) at each subtype. Its potency (pIC(50)) was 12 times higher in spleen (8.3 +/- 0.1, n=4) than in vas deferens (7.2 +/- 0.1, n=4) or aorta (7.2 0.1, n=4). In radioligand binding assays, p-TIA decreased the number of binding sites (B,,,,,,) in membranes from HEK293 cells expressing the rat alpha(1B)-adrenoceptors without affecting affinity (K-D), In contrast, in HEK293 cells expressing rat alpha(1A)- or alpha(1D)-adrenoceptors, p-TTA decreased the KD without affecting the B-max. It is concluded that p-TIA will be useful for distinguishing the role of particular alpha(1)-adrenoceptor subtypes in native tissues. (C) 2004 Elsevier B.V. All rights reserved.

Structure characterization of molecular complexes for non-linear optical materials. II. 1 : 1 complexes of 4-methyl-morpholine-N-oxide (1) and 3-picoline-N-oxide (2) with 2,4,6-trinitrophenol, studied by X-ray, AM1 and DFT calculations

(1) C6H2N3O7- center dot C5H12NO2+, Mr = 346.26, P2(1)/c, a = 7.2356(6), b = 10.5765(9), c = 19.593(2) angstrom, 3 beta=95.101(6)degrees, V = 1493.5(2) angstrom(3), Z = 4, R-1 = 0.0414; (2) C6H2N3O7- center dot C6H8NO+, Mr = 38.24, P2(1)/n, a = 7.8713(5), b = 6.1979(7), c = 28.697(3) angstrom, beta = 90.028(7)degrees, V = 1400.0(2) angstrom(3), Z = 4, R-1 = 0.0416. The packing units in both compounds consist of hydrogen bonded cation-anion pairs. The (hyper)polarizabilities have been calculated for the crystallographic and optimized molecules, by AM1 and at the DFT/B3LYP(6-31G**) level.

Modulation of thyroid hormone receptors, TR alpha and TR beta, by using different doses of triiodothyronine (T3) at different times

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Transforming growth factor beta and apoptosis in leprosy skin lesions: possible relationship with the control of the tissue immune response in the Mycobacterium leprae infection

The course of leprosy depends of the host immune response which ranges from the lepromatous pole (LL) to the tuberculoid pole (TT). A comparative study was conducted in 60 patients with the LL and TT The results showed a mean expression of TGF-beta of 339 +/- 99.4 cells/field for TT and of 519.2 +/- 68.2 cells/field for LL. Frequency of apoptosis was 6.3 +/- 1.8 in TT and 14.0 +/- 6.1 in LL. A correlation (p = 0.0251) between TGF-beta and caspase-3 in the LL was found. This finding indicates a role of TGF-beta and apoptosis in the immune response in leprosy. (C) 2012 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

Oxidized low density lipoprotein impairs endothelial progenitor cell function by downregulation of E-selectin and integrin alpha(v)beta5

BACKGROUND: Oxidized low density lipoprotein (oxLDL) has been shown to induce apoptosis and senescence of endothelial progenitor cells (EPC). In the present study, we hypothesized that even sub-apoptotic concentrations of oxLDL impair the angiogenic potential of EPC and investigated if this effect is mediated by affecting adhesion and incorporation. METHODS: A co-culture system of human microvascular endothelial cells and EPC was used to study the effect of sub-apoptotic concentrations of native (nLDL) and oxLDL on cell-cell interaction. The expression and the functional role of angiogenic adhesion molecules and integrins was monitored by FACS and neutralizing assay, respectively. RESULTS: We observed an inhibition of tube formation and impairment of EPC integration into the vascular network of mature endothelial cells by oxLDL. In contrast, nLDL did not affect angiogenic properties of EPC. Incubation of EPC with sub-apoptotic oxLDL concentrations significantly decreased E-selectin and integrin alpha(v)beta(5) expression (37.6% positive events vs. 71.5% and 24.3% vs. 49.9% compared to control culture media without oxLDL). Interestingly, expression of alpha(v)beta(3), VE-cadherin and CD31 remained unchanged. Blocking of E-selectin and integrin alpha(v)beta(5) by neutralizing antibody effectively inhibited adhesion of EPC to differentiated endothelial cells (56.5% and 41.9% of control; p<0.001). CONCLUSION: In conclusion, oxidative alteration of LDL impairs angiogenic properties of EPC at sub-apoptotic levels by downregulation of E-selectin and integrin alpha(v)beta(5), both substantial mediators of EPC-endothelial cell interaction.