281 research outputs found
Reversion of nitrate tolerance in rat aorta rings by freeze-dried red wine
No full textChronically administered organic nitrates induce nitrate tolerance and endothelial dysfunction, which limit their therapeutic use. eNOS uncoupling, ROS over-production, aldehyde dehydrogenase-2 as well as superoxide dismutase (SOD) oxidative inhibition, and cGMP desensitization are thought to play an important role. Natural polyphenols are effective antioxidants, which might counteract the mechanisms leading to nitrate tolerance. The aim of this work was to verify whether freeze-dried (dealcoholized) red wine (FDRW) was able to revert glyceryl trinitrate (GTN) tolerance and endothelial dysfunction induced in rat aorta rings with either GTN or diethyldithiocarbamate (DETCA), an irreversible inhibitor of Cu/Zn SOD. GTN induced a concentration-dependent relaxation of rings pre-contracted with phenylephrine. GTN spasmolysis was significantly reduced in rings pre-incubated with either GTN or DETCA. FDRW, at 2.8 μg of gallic acid equivalents (GAE)/mL concentration, was able to revert partially, though significantly, GTN-induced tolerance but not tolerance and endothelial dysfunction induced by DETCA. This work provides the first evidence in vitro that red wine components, at concentrations comparable to those achieved in human blood after moderate consumption of red wine, revert tolerance to nitrates with a mechanism possibly mediated by SOD
[4+2]Cycloaddition on densely functionalized cyclopentadiene
No full textThe Diels-Alder (DA) and hetero-Diels-Alder (HDA) reaction of N-(2,4-dicyano-1,5-dimethyl-3-phenylcyclopenta-2,4-dienyl)-2,2,2-trifluoroacetamide 1 can be conveniently used for the synthesis of biarylic and polycyclic compounds, depending on whether you use alkynes or alkenes as dienophiles. We observe a totally regioselectivity and endo-diastereoselectivity of the cycloaddition reactions
Gold nanoparticles potentiate CaVchannel currents in rat tail artery myocytes
No full textThis study was designed to unveil effects of 5-nm sized, polyvinylpyrrolidone-coated gold nanoparticles (AuNPs) on vascular CaV1.2 and CaV3.1 channels. Ba2+currents through both channels (IBa1.2and IBa3.1) were recorded in single myocytes isolated from the rat tail main artery by means of the whole-cell patch-clamp method. AuNPs increased IBa1.2and IBa3.1amplitude in a concentration- and Vh-dependent manner. Neither the voltage dependence of inactivation and activation curves nor inactivation and activation kinetics were affected by AuNPs. In conclusion, these findings warrant further investigation to clarify whether different types of NPs possess the same stimulatory activity and may represent a toxic hazard to humans
Photocycloaddition on 2-Methyloxazolo[5,4-b] pyridine: a route to the oxazolo[5,4-b]azocine system
No full textRegio- and stereospecific cycloaddition of acrylonitrile and 2-butenenitrile on 2-Methyloxazolo[5,4-b]pyridine, followed by ring-opening, lead to 2-Methyloxazolo[5,4-b]dihydroazocines as main products
Quercetin as a novel activator of L-type Ca2+ channels in rat tail artery smooth muscle cells
No full text1. The aim of this study was to investigate the effects of quercetin, a natural polyphenolic flavonoid, on voltage-dependent Ca(2+) channels of smooth muscle cells freshly isolated from the rat tail artery, using either the conventional or the amphotericin B-perforated whole-cell patch-clamp method. 2. Quercetin increased L-type Ca(2+) current [I(Ca(L))] in a concentration- (pEC(50)=5.09+/-0.05) and voltage-dependent manner and shifted the maximum of the current-voltage relationship by 10 mV in the hyperpolarizing direction, without, however, modifying the threshold and the equilibrium potential for Ca(2+). 3. Quercetin-induced I(Ca(L)) stimulation was reversible upon wash-out. T-type Ca(2+) current was not affected by quercetin. Quercetin shifted the voltage dependence of the steady-state inactivation and activation curves to more negative potentials by about 5.5 and 7.5 mV respectively, in the mid-potential of the curves as well as increasing the slope of activation. Quercetin slowed both the activation and the deactivation kinetics of the I(Ca(L)). The inactivation time course was also slowed but only at voltages higher than 10 mV. Moreover quercetin slowed the rate of recovery from inactivation. 4. These results prove quercetin to be a naturally-occurring L-type Ca(2+) channel activator
Trapping of photochemical intermediates as a tool in organic synthesis. Preparation of spiroaziridinopyridones, a new heterocyclic system
No full textWhereas alkyl lithium and Grignard reagents both at rt and at -80°C thermally react with 3-methylisoxazolo[5,4-b]pyridine giving alkylation and/or isoxazole ring opening products, sodium malonate and sodium boron hydride react only under UV irradiation. Selective trappings of ketenimine or azirine intermediates give an enaminopyridone or two diasteroisomeric spiroaziridinopirydones. Regioselective opening of the aziridine ring with perchloric acid gives 3(1-amino-ethyl)-1H-pyridin-2-one. © 2002 Elsevier Science Ltd. All rights reserved
Perivascular adipose tissue modulates the effects of flavonoids on rat aorta rings: role of superoxide anion and β3 receptors
No full text: Several studies demonstrate the beneficial effects of dietary flavonoids on the cardiovascular system. Since perivascular adipose tissue (PVAT) plays an active role in the regulation of vascular tone in both health and diseases, the present study aimed to assess the functional interaction between PVAT and flavonoids in vitro on rat aorta rings. Several flavonoids proved to display both antispasmodic and spasmolytic activities towards noradrenaline-induced contraction of rings deprived of PVAT (-PVAT). However, on PVAT-intact (+PVAT) rings, both actions of some flavonoids were lost and/or much decreased. In rings-PVAT, the superoxide donor pyrogallol mimicked the effect of PVAT, while in rings+PVAT the antioxidant mito-tempol restored both activities of the two most representative flavonoids, namely apigenin and chrysin. The Rho-kinase inhibitor fasudil, or apigenin and chrysin concentration-dependently relaxed the vessel active tone induced by the Rho-kinase activator NaF; the presence of PVAT counteracted apigenin spasmolytic activity, though only in the absence of mito-tempol. Similar results were obtained in rings pre-contracted by phenylephrine. Finally, when β3 receptors were blocked by SR59230A, vasorelaxation caused by both flavonoids was unaffected by PVAT. These data are consistent with the hypothesis that both noradrenaline and apigenin activated adipocyte β3 receptors with the ensuing release of mitochondrial superoxide anion, which once diffused toward myocytes counteracted flavonoid vasorelaxant activity. This phenomenon might limit the beneficial health effects of dietary flavonoids in patients affected by either obesity and/or other pathological conditions characterized by sympathetic nerve overactivity
Medical education and attitudes about acute otitis media guidelines: a survey of Italian pediatricians and otolaryngologists.
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Medical Education and Attitudes About Acute Otitis Media Guidelines A Survey of Italian Pediatricians and Otolaryngologists
Author(s): Marchisio, P (Marchisio, Paola); Mira, E (Mira, Eugenio)2; Klersy, C (Klersy, Catherine)3; Pagella, F (Pagella, Fabio)2; Esposito, S (Esposito, Susanna); Bianchini, S (Bianchini, Sonia); Di Mauro, G (Di Mauro, Giuseppe)4; Fusi, M (Fusi, Michela); Nazzari, E (Nazzari, Erica); Tagliabue, M (Tagliabue, Marta)2; Bellussi, L (Bellussi, Luisa)5; Principi, N (Principi, Nicola)1
Source: PEDIATRIC INFECTIOUS DISEASE JOURNAL Volume: 28 Issue: 1 Pages: 1-4 DOI: 10.1097/INF.0b013e318184ef02 Published: JAN 2009
Times Cited: 7 (from Web of Science)
Cited References: 36 [ view related records ] Citation Map
Abstract: Background: Medical education and guidelines have been advocated as major means of improving the managernent of otitis media. Limited data are available concerning medical education in acute otitis media (AOM), and the association between medical education and attitudes about AOM guidelines has never been explored.
Objectives: To assess the prevalence of medical education concerning AOM, of a Positive attitude toward AOM guidelines and of appropriate diagnostic methods in a large sample of Italian pediatricians (PEDs) and otolaryngologist (ENTs) and to look for possible associations between them.
Subjects and Methods: This cross-sectional survey was based on the responses of 2012 physicians (1160 PEDs and 852 ENTs) to a mailed anonymous questionnaire.
Results: Very few (9%) of the responders had received any AOM medical education during Medical school, but the number increased (hiring residency (38%) and peaked in the postresidency period (53%) with slight differences between PEDs and ENTs. Forty percent reported a positive attitude toward AOM guidelines, with PEDs having a better attitude than ENTs (46% vs. 32%, P < 0.001), An appropriate diagnostic method for AOM was reported by only 21% of the physicians (PEDs 11% vs. ENTs 35%, P < 0.001). AOM Medical education during postresidency and reporting the use of appropriate diagnostic methods were significantly associated With a positive attitude about AOM guidelines.
Conclusions: Specific educational programs concerning AOM should be implemented and rigorously evaluated, before physicians become fully trained PEDs and ENTs, and maintained during postresidency. Evidence-based guidelines should be further incorporated into everyday practice of both PEDs and ENTs
Quercetin antagonism of Bay K 8644 effects on rat tail artery L-type Ca(2+) channels
No full textThe functional interaction between two L-type Ca(2+) channel activators, quercetin and (S)-(-)-methyl-1,4-dihydro-2,6-dimethyl-3-nitro-4-(2-trifluoromethylphenyl)pyridine-5-carboxylate (Bay K 8644), has been investigated in vascular smooth muscle cells. L-type Ca(2+) currents [I(Ca(L))] were recorded in freshly isolated rat tail main artery myocytes using the whole-cell patch-clamp method. Bay K 8644 increased I(Ca(L)) in a concentration-dependent manner with a pEC(50) value of 8.25. Pre-incubation of myocytes with concentrations of quercetin per se ineffective as an L-type Ca(2+) channel activator (0.1 and 0.3 microM) inhibited significantly the maximal response evoked by Bay K 8644, but left unaltered its potency. Quercetin (0.1 microM) prevented the hyperpolarizing shift of the steady-state inactivation curve induced by 0.1 microM Bay K 8644 and its stimulation of I(Ca(L)) tail current intensity without modifying Bay K 8644-induced effects on I(Ca(L)) activation, inactivation, deactivation kinetics as well as on use-dependence and recovery from inactivation. Quercetin at nutritionally meaningful concentrations, limited the responsiveness of vascular L-type Ca(2+) channels to the pharmacological stimulation operated by Bay K 8644. These data contribute to a better understanding of quercetin effects on experimental in vivo cardioprotection
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