Physicochemical characterization of nanoparticles formed between DNA and phosphorylcholine substituted chitosans

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Vesicle-micelle transition in aqueous mixtures of the cationic dioctadecyldimethylammonium and octadecyltrimethylammonium bromide surfactants

The vesicle-micelle transition in aqueous mixtures of dioctadecyidimethylammonium and octadecyltrimethylammonium bromide (DODAB and C(18)TAB) cationic surfactants, having respectively double and single chain, was investigated by differential scanning calorimetry (DSQ, steady-state fluorescence, dynamic light scattering (DLS) and surface tension. The experiments performed at constant total surfactant concentration, up to 1.0 mM, reveal that these homologous surfactants mix together to form mixed vesicles and/or micelles, depending on the relative amount of the surfactants. The melting temperature T-m of the mixed DODAB-C(18)TAB vesicles is larger than that for the neat DODAB in water owing to the incorporation of C(18)TAB in the vesicle bilayer. The surface tension decreases sigmoidally with C(18)TAB concentration and the inflection point lies around (XDODAB) approximate to 0.4, indicating the onset of micelle formation owing to saturation of DODAB vesicles by C(18)TAB molecules. When XDODAB > 0.5 C(18)TAB molecules are mainly solubilised by the vesicles, but when XDODAB < 0.25 micelles are dominant. Fluorescence data of the Nile Red probe incorporated in the system at different surfactant molar fractions indicate the formation of micelle and vesicle structures. These structures have apparent hydrodynamic radius RH of about 180 and 500-800 nm, respectively, as obtained by DLS measurements. (C) 2007 Elsevier B.V. All rights reserved.

Extruded vesicles of dioctadecyldimethylammonium bromide and chloride investigated by light scattering and cryogenic transmission electron microscopy

Combined dynamic and static light scattering (DLS, SLS) and cryogenic transmission electron microscopy (cryo-TEM) were used to investigate extruded cationic vesicles of dioctadecyldimethylammonium chloride and bromide (DODAX, X being Cl- or Br-). In salt-free dispersions the mean hydrodynamic diameter, D-h, and the weight average molecular weight, M-w, are larger for DODAB than for DODAC vesicles, and both D-h and M-w increase with the diameter (phi) of the extrusion filter. NaCl (NaBr) decreases (increases) the DODAB (DODAC) vesicle size, reflecting the general trend of DODAB to assemble as larger vesicles than DODAC. The polydispersity index is lower than 0.25, indicating the dispersions are rather polydisperse. Cryo-TEM micrographs show that the smaller vesicles are spherical while the larger ones are oblong or faceted, and the vesicle samples are fairly polydisperse in size and morphology. They also indicate that the vesicle size increases with phi and DODAB assembles as larger vesicles than DODAC. Lens-shaped vesicles were observed in the extruded preparations. Both light scattering and cryo-TEM indicate that the vesicle size is larger or smaller than phi when phi is smaller or larger than the optimal phi* approximate to 200 nm. (C) 2008 Elsevier B.V. All rights reserved.

Aggregation behavior of aqueous dioctadecyldimethylammonium bromide/monoolein mixtures: A multitechnique investigation on the composition and temperature

A recently described non-viral gene delivery system [dioctadecyldimethylammonium bromide (DODAB)/monoolein (MO)] has been studied in detail to improve knowledge on the interactions between lamellar (DODAB) and non-lamellar-forming (MO) lipids, as a means to enhance their final cell transfection efficiency. Indeed, the morphology, fluidity, and size of these cationic surfactant/neutral lipid mixtures play an important role in the ability of these systems to complex nucleic acids. The different techniques used in this work, namely dynamic light scattering (DLS), fluorescence spectroscopy, differential scanning calorimetry (DSC), cryogenic transmission electron microscopy (cryo-TEM), light microscopy (LM), and surface pressure-area isotherms, allowed fully characterization of the phase behavior and aggregate morphology of DODAB/MO mixtures at different molar ratios. Overall, the results indicate that the final morphology of DODAB/MO aggregates depends on the balance between the tendency of DODAB to form zero-curvature bilayer structures and the propensity of MO to form non-bilayer structures with negative curvature. These results also show that in the MO-rich region, an increase in temperature has a similar effect on aggregate morphology as an increase in MO concentration. (C) 2012 Elsevier B.V. All rights reserved.

Effect of uroguanylin on potassium and bicarbonate transport in rat renal tubules

The effect of uroguanylin (UGN) oil K(+) and H(+) secretion in the renal tubules of the rat kidney was studied using in vivo stationary microperfusion. For the study of K(+) secretion, a tubule was Punctured to inject a column of FDC-green-colored Ringer's solution with 0.5 mmol KCI/L 10(-6)(mol UGN/L, and oil was Used to block fluid flow. K(+) activity and transepithelial potential differences (PD) were measured with double microelectrodes (K(+) ion-selective resin vs. reference) in the distal tubules of the same nephron. During perfusion, K(+) activity rose exponentially, from 0.5 mmol/L to stationary concentration, allowing for the calculation of K(+) secretion J(K)). JK increased from 0.63 +/- 0.06 nmol.cm(-2).s(-1) in the control croup to 0.85 +/- 0.06 in the UGN group (p < 0.01). PD was -51.0 +/- 5.3 mV in the control group and -50.3 +/- 4.98 mV in the UGN group. In the presence of 10(-7) mol iberiotoxin/L, the UGN effect was abolished: JK was 0.37 +/- 0.038 nmol-cm(-2).s(-1) in the absence of, and 0.38 +/- 0.025 in the presence of, UGN. indicating its action oil rnaxi-K channels. In another series of experiments, renal tubule acidification was studied, using similar method: proximal and distal tubules were perfused with solutions containing 25 mmol NaHCO(3)/L. Acidification half-time was increased both in proximal and distal segments and, as a consequence, bicarbonate reabsorption decreased in the presence of UGN (in proximal tubules, from 2.40 +/- 0.26 to 1.56 +/- 0.21 nmol-cm(-2).s(-1)). When the Na(+)/H(+) exchanger was inhibited by 10(-4) mol hexamethylene amiloride (HMA)/L, the control and UGN groups were not significantly different. In the late distal tubule, after HMA, UGN significantly reduced J(HCO3)(-). indicating all effect of UGN oil H(+)-ATPase. These data show that UGN stimulated J(K)(+) by actin, oil maxi-K channels. and decreased J(HCO3)(-) by acting on NHE3 in proximal and H(+)-ATPase in distal tubules.

pH at the micellar interface: Synthesis of pH probes derived from salicylic acid, acid-base dissociation in sodium dodecyl sulfate micelles, and Poisson-Boltzmann simulation

The study of the H+ concentration at the micellar interface is a convenient system for modeling the distribution of H+ at interfaces. We have synthesized salicylic acid derivatives to analyze the proton dissociation of both the carboxylic and phenol groups of' the probes, determining spectrophotometrically the apparent pK(a)'s (pK(ap)) in sodium dodecyl Sulfate, SDS, micelles with and without added salt. The synthesized probes were 2-hydroxy-5-(2-trimethylammoniumacetyl)benzoate; 2-hydroxy-5-(2-dimethylhexadecylammoniumacetyl)benzoate- 2-hydroxy-5-(2-dimethylhexadecylammoniumhexanoyl)benzoate-, 2-hydroxy-5-(2-diniethylhexadecylammoniumundecanoyl)betizoate; 2-hydroxy-5-acetylbenzoic acids and 2-hydroxy-5-dodecanoylbenzoic acid. Upon incorporation into SDS micelles the pK(ap)'s of both carboxylic and phenol groups increased by ca. 3 pH units and NaCl addition caused a decrease in the probe-incorporated pKap. The experimental results were fitted with a cell model Poisson-Boltzmann (P-B) equation taking in consideration the effect of salt on the aggregation number of SDS and using the distance of' the dissociating group as a parameter. The conformations of the probes were analyzed theoretically using two dielectric constants, e.g., 2 and 78. Both the P-B analysis and conformation calculations can be interpreted by assuming that the acid groups dissociate very close to, or at, the interface. Our results are consistent with the assumption that the intrinsic pK(a)'s of both carboxylic and phenol groups of the salicylic acid probes used here can be taken as those in water. Using this assumption the micellar and salt effects on the pKap's of the (trialkylammonium)benzoate probes were described accurately using a cell model P-B analysis. (c) 2005 Elsevier B.V. All rights reserved.

INTRATRACHEAL INJECTION OF NICKEL CHLORIDE AND COPPER-ZINC SUPEROXIDE-DISMUTASE ACTIVITY IN LUNG OF RATS

Superoxide radical (O2-) is a free radical that may be involved in various toxic processes. Cu-Zn superoxide dismutase catalyses the dismutation of the superoxide free radical and protects cells from oxidative damage, and it has been used clinically. The concentration of Ni2+ and Cu-Zn superoxide dismutase activity were measured in lungs of rats at time intervals of 5, 12, 19, 26, 33, and 40 days following an intratracheal injection of 127 nmol of NiCl2. Nickel chloride increased nickel content and resulted in a significant increase of Cu-Zn superoxide dismutase activity in lungs. This elevation of Cu-Zn superoxide dismutase activity was highest on the 12th day (approximately threefold) and is at levels comparable to controls rats on day 40 onwards. Since Cu-Zn superoxide dismutase activity was increased in lung throughout our experimental period without corresponding increases of Cu2+ and Zn2+, we speculate that the elevation of Cu-Zn superoxide dismutase activity might be due to an increased half-life of the enzyme, induced by nickel.

Synthesis, growth process and photoluminescence properties of SrWO4 powders

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Adsorption of MX2 (M = Mn, Ni, Cu, Zn, and Cd; X = Cl, Br, and I) and FeCl3 by modified silica surface with imidazolylpropyl group

Silica gel surface modified with imidazolylpropyl group was used to adsorb MX2 (M = Mn, Ni, Cu, Zn, and Cd; X = Cl, Br, and I) and FeCl3 from ethanol and acetone solution. The adsorption capacity and the intensity of the adsorption were determined by using the Langmuir equation. The influences of the solvent, temperature, and degree of functionalization on the adsorption were also studied. The infrared spectra of the functionalized silica were recorded between 1700-1300 cm-1. The bands of the imidazole skeletal vibrations are shifted to higher frequencies upon metal-to-base nitrogen interaction. © 1985.

Adsorption of various ions from acetone and ethanol on silica gel modified with 2-, 3-, and 4-aminobenzoate

Chemically bonded phases were obtained by reaction of 2-, 3-, and 4-aminobenzoate with 3-chloropropyl-silica gel. These phases were employed for metal cation adsorption in a batch method and applied to the separation of transition metal cations by chromatographic analysis.

Tracheobronchial consequences of the use of heat and moisture exchangers in dogs

Purpose: To determine the effect of heat and moisture exchange (HME) on the tracheobronchial tree (TBT) using a unidirectional anesthesic circuit with or without CO2 absorber and high or low fresh gas flow (FGF), in dogs. Methods: Thirty-two dogs were randomly allocated to four groups: G1 (n = 8) valvular circuit without CO2 absorber and high FGF (5 L·min-1); G2 (n = 8) as G1 with HME; G3 (n = 8) circuit with CO2 absorber with a low FGF (1 L·min-1); G4 (n = 8) as G3 with HME. Anesthesia was induced and maintained with pentobarbital. Tympanic temperature (TT), inhaled gas temperature (IGT), relative (RH) and absolute humidity (AH) of inhaled gas were measured at 15 (control), 60, 120 and 180 min of controlled ventilation. Dogs were euthanized and biopsies in the areas of TBT were performed by scanning electron microscopy. Results: The G2 and G4 groups showed the highest AH (>20 mgH2O·L-1) and G1 the lowest (< 10 mgH2O·L-1) and G3 was intermediate (<20 mgH2O·L-1) (P < 0.01). There was no difference of TT and IGT among groups. Alterations of the mucociliary system were greatest in G1, least in G2 and G4, and intermediate in G3. Conclusion: In dogs, introduction of HME to a unidirectional anesthetic circuit with/without CO2 absorber and high or low FGF preserved humidity of inspired gases. HME attenuated but did not prevent alterations of the mucociliary system of the TBT.

Synergistic action of olive oil supplementation and dietary restriction on serum lipids and cardiac antioxidant defences

Caloric intake is higher than recommended in many populations. Therefore, enhancing olive oil intake alone may not be the most effective way to prevent cardiovascular diseases. The purpose of the present study was to analyse the association of olive oil and dietary restriction on lipid profile and myocardial antioxidant defences. Male Wistar rats (180-200 g, n = 6) were divided into 4 groups: control ad libitum diet (C), 50% restricted diet (DR), fed ad libitum and supplemented with olive oil (3 mL/(kg-day)) (OO), and 50% restricted diet and supplemented with olive oil (DROO). After 30 days of treatments, OO, DR, and DROO groups had increased total cholesterol and high-density lipoprotein cholesterol concentrations. DR and DROO animals showed decreased low-density lipoprotein cholesterol. DROO had the lowest low-density lipoprotein cholesterol concentration. Total lipids and triacylglycerols were raised by dietary restriction and diminished by olive oil. OO rats had higher myocardial Superoxide dismutase and lower catalase and glutathione peroxidase activities than C rats. DR and DROO showed enhanced cardiac Superoxide dismutase, catalase, and glutathione peroxidase activities from the control. Olive oil supplementation alone improved the lipid profile but was more effective when coupled with dietary restriction. There was a synergistic beneficial action of dietary restriction and olive oil on serum lipids and myocardial antioxidant defences.

Effects of olive oil and its minor constituents on serum lipids, oxidative stress, and energy metabolism in cardiac muscle

Recent lines of evidence suggest that the beneficial effects of olive oil are not only related to its high content of oleic acid, but also to the antioxidant potential of its polyphenols. The aim of this work was determine the effects of olive oil and its components, oleic acid and the polyphenol dihydroxyphenylethanol (DPE), on serum lipids, oxidative stress, and energy metabolism on cardiac tissue. Twenty four male Wistar rats, 200 g, were divided into the following 4 groups (n = 6): control (C), OO group that received extra-virgin olive oil (7.5 mL/kg), OA group was treated with oleic acid (3.45 mL/kg), and the DPE group that received the polyphenol DPE (7.5 mg/kg). These components were administered by gavage over 30 days, twice a week. All animals were provided with food and water ad libitum The results show that olive oil was more effective than its isolated components in improving lipid profile, elevating high-density lipoprotein, and diminishing low-density lipoprotein cholesterol concentrations. Olive oil induced decreased antioxidant Mn-superoxide dismutase activity and diminished protein carbonyl concentration, indicating that olive oil may exert direct antioxidant effect on myocardium. DPE, considered as potential antioxidant, induced elevated aerobic metabolism, triacylglycerols, and lipid hydroperoxides concentrations in cardiac muscle, indicating that long-term intake of this polyphenol may induce its undesirable pro-oxidant activity on myocardium. © 2006 NRC Canada.

Application of a serum/protein-free medium for the growth of mammalian cell lines and high level production of classical, variant and very virulent strain of infectious bursal disease virus (IBDV)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Highlights from the I international symposium of thrombosis and anticoagulation in internal medicine, October 23-25, 2008, Sao Paulo, Brazil

The importance of thrombosis and anticoagulation in clinical practice is rooted firmly in several fundamental constructs that can be applied both broadly and globally. Awareness and the appropriate use of anticoagulant therapy remain the keys to prevention and treatment. However, to assure maximal efficacy and safety, the clinician must, according to the available evidence, choose the right drug, at the right dose, for the right patient, under the right indication, and for the right duration of time. The first International Symposium of Thrombosis and Anticoagulation in Internal Medicine was a scientific program developed by clinicians for clinicians. The primary objective of the meeting was to educate, motivate and inspire internists, cardiologists and hematologists by convening national and international visionaries, thought-leaders and dedicated clinician-scientists in Sao Paulo, Brazil. This article is a focused summary of the symposium proceedings. © Springer Science+Business Media, LLC 2009.