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•Sr-morin complex spontaneously forms at Langmuir monolayers.•Sr-morin complex formation change the lipid organization at the air-liquid interface.•Complexation was followed by UV–vis ...absorption and fluorescence techniques.•LB films harboring the Sr-morin complex support in vitro osteoblast growth.
Flavonoid-metal complexes are widely studied because of their interesting luminescent behavior and biological activity. Despite the extensive exploration of flavonoid-metal coordination processes in solution, the formation of complexes using the flavonoid molecule inserted in a lipid membrane has been little investigated. This effect could provide important insight into the biological activity of flavonoids at lipid membranes and could represent an attractive strategy to design supramolecular structures. Here, we studied the complexation between Sr2+ and morin inserted in an octadecylphosphonic acid (OPA) Langmuir monolayer. This is a relevant system due to the synergism imposed by the association of the Sr2+ ability to control bone formation/resorption with the morin antioxidative effect. Morin incorporation into the OPA monolayers and further Sr2+ complexation were monitored by surface pressure isotherms. Electronic absorption spectroscopy and fluorescence techniques showed Sr-morin complexation both in solution and at the air-liquid interface. Although morin complexation has been described to occur only at basic pH, the specific thermodynamic properties at the air-liquid interface drove metal complexation. LB films were deposited on Ti surfaces, and the resulting OPA/Sr-morin coatings exhibited high surface free energy and increase on its polar component. This optimized surface feature supported further serum protein adsorption and osteoblast growth and differentiation, indicating that these lipid-based coatings are promising for bioactive coating design. This study paves the way for the use of this lipid-based coating in the design of implants for faster osteointegration. Moreover, flavonoid-metal complexation at membranes could also help to shed light on the biological role played by flavonoids.
Abstract In sheep, neither the in vivo effect of vasopressin administered by a method other than systemic infusion nor the central effects on behavior from the perspective of stress regulation has ...been fully elucidated in an intact animal. We examined changes in behavioral, adrenocorticotropic, and autonomic nervous functions after intracerebroventricular infusions of arginine vasopressin (AVP) to elucidate its central role. Intracerebroventricular infusions of AVP (0, 0.12, 1.2 and 12 μg/500 μl/30 min) evoked a dose-related increase in plasma cortisol concentration. There were significant treatment-related effects on the total duration of sham-chewing (Friedman's test, X2 = 12.75, p = .0052), on the total duration of bar-biting (Friedman's test, X2 = 15.0, p = .0018), and on the total duration of rubbing (Friedman's test, X2 = 12.0, p = .0074). AVP 12 μg treatment induced a greater degree of sham-chewing and bar-biting than the other three treatments did (Nemenyi multiple comparisons: p < 0.1). These findings indicate, together with our previous findings, that AVP has the same corticotropic potential as corticotropin-releasing hormone infused intracerebroventricularly in equal molar concentrations. Although the degree to which central stress signaling pathways are involved in these responses remains speculative, the relationships between stereotypies and central AVP are of particular interest.
Acridine orange interaction with DNA: Effect of ionic strength Amado, André M.; Pazin, Wallance M.; Ito, Amando S. ...
Biochimica et biophysica acta. General subjects,
April 2017, 2017-Apr, 2017-04-00, 20170401, Letnik:
1861, Številka:
4
Journal Article
Recenzirano
The study of acridine orange (AO) spectral characteristics and the quenching of its singlet and triplet excited states by TEMPO radical at its binding to DNA in the function of the DNA concentration ...and in the absence and presence of NaCl is reported.
The study was performed using steady-state and time resolved optical absorption and florescence, fluorescence correlation spectroscopy and resonant light scattering techniques.
The presence of different species in equilibrium: AO monomers and aggregates bound to DNA, has been demonstrated, their relative content depending on the DNA and the AO concentrations. At high DNA concentration the AO monomers are protected against the contact with other molecules, thus reducing the AO excited state quenching. The addition of NaCl reduces the AO binding constant to DNA, thus reducing the AO and DNA aggregation.
The interaction of AO with DNA is a complex process, including aggregation and disaggregation of both components. This modifies the AO excited state characteristics and AO accessibility to other molecules. The salt reduces the DNA effects on the AO excited state characteristics thus attenuating its effects on the AO efficacy in applications.
This study demonstrates that the interaction of photosensitizers with DNA, depending on their relative concentrations, can both decrease and increase the photosensitizer efficacy in applications. The salt is able to attenuate these effects.
•DNA in low concentrations stimulates the Acridine Orange (AO) aggregation.•The further DNA concentration increase induces the AO disaggregation.•At high DNA concentrations it forms aggregates around AO molecules.•The binding with DNA reduces the probability of the AO contacts with other molecules.•The presence of NaCl reduces the probability of the AO binding with DNA and the AO aggregation.
It is well known that beta-adrenoceptor agonists (beta-agonists) cause relaxation in airway smooth muscle mediated by a reduction in the concentration of intracellular Ca2+ (Ca2+(i)). However, little ...is currently known regarding whether reduced sensitization to Ca2+ is involved in the beta-adrenergic relaxation.
This study was designed to determine the intracellular mechanisms underlying suppression of Ca2+ sensitization in beta-adrenergic relaxation (Ca(2+)-independent relaxation by beta-agonists). Methods Isometric tension and Ca2+(i) were simultaneously measured in fura-2-loaded strips isolated from guinea-pig tracheal smooth muscles. The relationships between tension and Ca2+(i) were examined in the inhibitory action of isoprenaline (ISO) and other cAMP-related agents against methacholine-induced contraction.
The concentration-inhibition curve for ISO against methacholine in tension was significantly dissociated from the curve for ISO in Ca2+(i). In ISO-induced relaxation, a reduction in tension was significantly greater than that in Ca2+(i.) This phenomenon was mimicked by other cAMP-related agents: forskolin and dibutyryl-cAMP. In contrast, the inhibitory action of SKF-96365, a non-selective inhibitor of Ca(2+) channels, was associated with that in Ca2+(i). In the presence of Rp-cAMPS, an inhibitor of protein kinase A (PKA), ISO caused an equivalent relaxation with less reduction in Ca2+(i). The effects of ISO were not affected by Y-27632, an inhibitor of Rho-kinase, or by bisindolylmaleimide, an inhibitor of protein kinase C. ISO failed to inhibit contraction elicited by calyculin A, an inhibitor of myosin phosphatase. Conclusion beta-Adrenergic action antagonizes not only Ca2+ mobilization but also Ca2+ sensitization in methacholine-induced contraction. The cAMP/PKA-independent, G(s)-direct action is more potent in Ca(2+)-independent relaxation by beta-agonists than the cAMP/PKA-dependent pathway. Moreover, myosin phosphatase is a fundamentally affected protein in the reduced response to Ca2+ mediated by beta-agonist. Our results may provide evidence that this Ca2+ desensitization is a novel target for a reliever medication using rapid-acting beta-agonists in acute asthma management.
We have studied the transcription regulation of the rat thromboxane synthase (TXS) gene by peroxisome proliferator-activated receptor γ (PPARγ) in macrophages. The transcription activity of a cloned ...5′-flanking region (1.6 kilobases) of the rat TXS gene (5′FL-TXS) was examined by luciferase reporter gene assay. TXS mRNA expression and the transcription activity of 5′FL-TXS were inhibited by PPARγ ligands, 15-deoxy-Δ12,14-prostaglandin J2(PGJ2), and the thiazolidinedione troglitazone (TRO) in a dose-dependent manner. Overexpression of PPARγ also significantly suppressed transcription, and further addition of PGJ2 or TRO augmented the suppression. Deletion analysis showed that the element responsible for the PPARγ effect is located in a region containing the nuclear factor E2 (NF-E2)/AP-1 site (−98/−88), which was indicated to be the major promoter of the TXS gene. By electrophoretic mobility shift assay using the NF-E2/AP-1 site and nuclear extracts from macrophages, we observed a specific protein-DNA complex formation, which was inhibited by a specific antibody against the transcription factor NRF2 (NF-E2-related factor2). Moreover, the complex was decreased with PGJ2, TRO, or in vitro translated PPARγ. The transcription suppression by PPARγ was confirmed using this truncated NRF2-binding element (−98/−88) by the reporter gene assay. Finally, a direct interaction between PPARγ and NRF2 was confirmed by glutathione S-transferase pull-down assay. In conclusion, the NRF2-binding site (−98/−88) is the major promoter of 5′FL-TXS which can be suppressed by activated PPARγ via a protein-protein interaction with NRF2 in macrophages.
Authors have grown AlN films on (Mn,Zn)Fe2O4 by pulsed laser deposition and investigated the growth temperature dependence of their structural properties using grazing-incidence X-ray reflection ...(GIXR), AFM, reflection high-energy electron diffraction (RHEED) and X-ray diffraction. Authors have confirmed that high-quality AlN films can be grown in the substrate temperature range from room temperature to 800 C. Authors have also found that the films grown at low temperatures have greater strain and smoother surfaces due to the reduced motion of atoms during growth. GIXR measurements have revealed that the abruptness of the heterointerface between the AlN films and the substrates is improved by a reduction in the growth temperature. 20 refs.
This article presents two methods for the fast computation of macroscopic magnetization model called assembled domain structure model. First, an efficient method for computing the demagnetizing field ...is proposed. Secondly, a direct searching method of equilibrium point is developed, which greatly reduces the computation time.
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