1,721,034 research outputs found
On the interaction between xanthine oxidase and actin.
No full textXanthine oxidase increases the rate of actin polymerization. This occurs at oxidase concentrations as low as 40 nM provided the concentration of the polymerizing agent is low (0.5 mM MgCl2). In the presence of 0.1 M KCl plus 1 mM MgCl2 as the polymerizing agents, xanthine oxidase does not affect the rate of the polymerization but increases significantly the rate of the conversion of F(ATP)actin into F(ADP.Pi)actin and probably also the rate of the orthophosphate release
Sulmazole effect on PGE2 and D-Ala2-Met-Enkephalinamide modulation of cyclic AMP synthesis and neurotransmitter release in guinea-pig superior cervical ganglion
No full textIn the guinea-pig superior cervical ganglion, the Gi blocking agent sulmazole enhanced the basal and prostaglandin E2-induced stimulation of cyclic AMP synthesis but had no effect on the prostaglandin-dependent inhibition of acetylcholine release. On the contrary sulmazole counteracted the inhibitory effect of D-Ala2-Met-enkephalinamide both on cyclic AMP formation and acetylcholine release. Moreover sulmazole eliminated the supra-additive effect of the combination of prostaglandin + opiate on cyclic AMP synthesis. The presence of a Gi-coupled opiate receptor at the pre-and postsynaptic levels is suggeste
Spray dried Eudragit microparticles as encapsulation devices for vitamin C
No full textThe aim of the present study was to produce methacrylate microparticles for the delivery (administration) of ascorbic acid via oral route. Vitamin C is an important antioxidant that may be involved in the reduction of the risk of certain types of cancer, such as colorectal cancer. As polymers different acrylic compounds were considered, namely Eudragit® RL, L and RS. Spray-drying was used as preparation method of vitamin C/Eudragit® microspheres. Microspheres were first characterized by size and morphology by scanning electron microscopy, then in vitro release kinetics by mean of dialysis method were studied. Although the produced microparticles were unable to slow down the release of the drug with respect to the free form of ascorbic acid, these microspheres showed a good morphology and size distribution that permit to propose them as candidate for the delivery of vitamin C as associated therapy in the treatment of colorectal cancer by oral route
Production of Eudragit microparticles by spray-drying technique: Influence of experimental parameters on morphological and dimensional characteristics
No full textPurpose. The aim of this study was to evaluate the influence of operating parameters on the characteristics of methacrylate microparticles prepared by spray drying technique.
Methods. Eudragit microparticles were prepared by a spray drying method. The influence of different experimental parameters (i.e. solvent, feed rate, air flow rate, air drying temperature and aspiration flow rate) was studied on microparticle morphology, size distribution and recovery. In addition different Eudragit type and Eudragit RS concentration were employed. Optical and electron microscopy were employed in order to analyse microparticle morphology and dimensional distribution. Finally prednisolone as model drug was encapsulated in Eudragit RS microparticles.
Results. Low feed rate values enabled to obtain the best results in term of microparticle morphology. Changes in nebulizing air flow did not result in a corresponding effect on microparticle characteristics. An increase of air drying temperature resulted in a reduction of microparticle dimension and recovery. A low flow of drying air was preferable as this resulted in microparticles with an optimal morphology. The polymer concentration affected both morphology and dimensions of microparticles. The encapsulation of prednisolone led to good incorporation efficiencies without altering percentage of recovery, morphology and mean dimension of the microparticles.
Conclusions. The selection of appropriate parameters enabled to obtain spray dried Eudragit RS microparticles characterized by good morphology and narrow dimensional distribution
Liver damage due to the administration of phenylhydrazine in Ictalurus sp.
No full textSpecimens of catfish (Ictalurus sp.) were treated with a sublethal dose of phenylhydrazine in order to reveal any liver ultrastructural alterations. Transmission electron microscope ultrastructural analysis of hepatocytes from liver fragments were compared with controls. From the 3rd day after administration of phenylhydrazine, in the vicinity of blood vessels, ultrastructural alterations of the hepatocytes were observed. By day 15 the hepatic parenchyma was manifesting maximum degeneration. An autoregenerative phase of the liver parenchyma was evident on the 21st da
Biodegradable microparticles for sustained delivery of tetracycline to the periodontal pocket: Formulatory and drug release studies
No full textThis paper describes the production and characterization of biodegradable microparticles containing tetracycline, designed for periodontal diseases therapy. The influence of production parameters was studied on microparticle characteristics and antibiotic release modality. Microparticles were made by using different preparation procedures and different polyesters, namely poly(L-lactide), L-PLA, poly(DL-lactide), DL-PLA and poly(DL-lactide-co-glycolide) 50:50, DL-PLG. A double emulsion preparation method together with a concentrated salt solution as external phase gave the best result in term of tetracycline incorporation efficacy. In vitro release experiments demonstrated that tetracycline is slowly and appropriately released from microparticles. Release kinetics were found to be influenced by the type of polymer utilized for microparticle production. In vitro experiments simulating in vivo condition, were carried out up to 30 days. Only DL-PLG microparticles showed significant changes in their morphology, whereas L-PLA and DL-PLA were found almost intact after the same period of time
"Low" concentrations of sodium fluoride inhibit neurotransmitter release from the guinea-pig superior cervical ganglion.
No full textThe role of G proteins and related second messenger system on the modulation of acetylcholine release from [3H]choline-preloaded guinea-pig superior cervical ganglion was investigated using the potent general activator NaF. The electrically evoked (1 Hz, 5 min) [3H] release was inhibited by “low” F− concentrations (1-2.5 mM), by the adenylyl cyclase blocker MDL 12330A (10 μM), alone and in combination with 1 mM NaF, and increased by 0.5 mM 8Br-cAMP, 100 μM forskolin and 0.5 mM 3-isobutyl-1-methylxantine. No effect of 1 mM F− was observed on spontaneous release. Fluoride-induced inhibition was counteracted by the G protein blocker sulmazole (1 mM), forskolin and alteration of calcium influx by increasing [Ca2+]out from 2.2 to 6 mM, raising the rate of stimulation (10 Hz, 30 s), or broadening the presynaptic action potential with 10 μM 4-aminopyridine and 50 μM tetraethylammonium chloride. Thus a NaF-sensitive G protein, linked to cAMP synthesis, is determinant for the inhibition of neurosecretion in this cholinergic synapse, involving Ca2+-dependent mechanisms
Keratinocytes oxidative damage mechanisms related to airbone particle matter exposure
Full text linkEpidemiological evidences have correlated airbone particulate matter (PM) to adverse health effects, mainly linking to pulmonary and cardiovascular disease. Nevertheless, only recently, some studies reported detrimental effects of PM on other organs such as skin. In a recent work, we have reported increased oxidative and inflammatory responses in Reconstituted Human Epidermis (RHE) exposed to ambient particles (CAPs) and we also demonstrated the ability of CAPs to penetrate the skin tissue.The present study was aimed to better understand the cellular mechanisms beyond the oxidative changes induced by CAPs (5-10-25. μg/mL) in human immortalized keratinocytes (HaCaT).After 24. h of treatment, CAPs were able to enter the cells leading to a decrease in viability, increased levels of 4-hydroxinonenal products (4-HNE) and IL-1α release. Overall these data, suggest lipid and protein oxidative damage, as well as an increase of inflammatory response after being challenged with CAPs. In addition, 3. h after CAPs exposure we found a significant increase in NF-kB and Nrf2 translocation into the nucleus. In contrast, no differences in gene expression and enzymatic activity of Nrf2 target genes were detected. This last finding could be explained by the ability of CAPs to possibly alter the binding of Nrf2 to the ARE DNA sequence.Fil: Romani, Arianna. Università di Ferrara; ItaliaFil: Cervellati, Carlo. Università di Ferrara; ItaliaFil: Muresan, Ximena M.. Università di Ferrara; ItaliaFil: Belmonte, Giuseppe. Università di Ferrara; ItaliaFil: Pecorelli, Alessandra. North Carolina State University; Estados UnidosFil: Cervellati, Franco. Università di Ferrara; ItaliaFil: Benedusi, Mascia. Università di Ferrara; ItaliaFil: Evelson, Pablo Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Bioquímica y Medicina Molecular. Universidad de Buenos Aires. Facultad Medicina. Instituto de Bioquímica y Medicina Molecular. Departamento de Patología; ArgentinaFil: Valacchi, Giuseppe. Università di Ferrara; Italia. North Carolina State University; Estados Unido
Skin damage mechanisms related to airborne particulate matter exposure
Full text linkEpidemiological studies suggest a correlation between increased airborne particulate matter (PM) and adverse health effects. The mechanisms of PM-health effects are believed to involve oxidative stress and inflammation. To evaluate the ability of PM promoting skin tissue damage, one of the main organs exposed to outdoor pollutants, we analyzed the effect of concentrated ambient particles (CAPs) in a reconstructed human epidermis (RHE) model. RHE tissues were exposed to 25 or 100 μg/ml CAPs for 24 or 48 h. Data showed that RHE seems to be more susceptible to CAPs-induced toxicity after 48 h exposure than after 24 h. We found a local reactive O2 species (ROS) production increase generated from metals present on the particle, which contributes to lipids oxidation. Furthermore, as a consequence of altered redox status, NFkB nucleus translocation was increase upon CAPs exposure, as well as cyclooxygenase 2 and cytochrome P450 levels, which may be involved in the inflammatory response initiated by PM. CAPs also triggered an apoptotic process in skin. Surprisingly, by transition electron microscopy analysis we showed that CAPs were able to penetrate skin tissues. These findings contribute to the understanding of the cutaneous pathophysiological mechanisms initiated by CAPs exposure, where oxidative stress and inflammation may play predominant roles.Fil: Magnani, Natalia Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Bioquímica y Medicina Molecular. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Bioquímica y Medicina Molecular; ArgentinaFil: Muresan, Ximena M.. Universita Di Ferrara; ItaliaFil: Belmonte, Giuseppe. Universita Di Ferrara; ItaliaFil: Cervellati, Franco. Universita Di Ferrara; ItaliaFil: Sticozzi, Claudia. Universita Di Ferrara; ItaliaFil: Pecorelli, Alessandra. Universita Di Ferrara; ItaliaFil: Miracco, Clelia. Università Degli Studi Di Siena; ItaliaFil: Marchini, Timoteo Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Bioquímica y Medicina Molecular. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Bioquímica y Medicina Molecular; ArgentinaFil: Evelson, Pablo Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Bioquímica y Medicina Molecular. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Bioquímica y Medicina Molecular; ArgentinaFil: Valacchi, Giuseppe. Universita Di Ferrara; Itali
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