245 resultados para adsorbed layers
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Porphyrins are currently used in photodynamic therapy as photosensitizers. In this paper we studied the interaction of two charged porphyrins, 5, 10, 15, 20-mesotetrakis(N-metyl-4-pyridyl) porphyrin, (TMPyP/chloride salt) cationic, and 5, 10, 15, 20-meso-tetrakis(sulfonatophenyl) porphyrin, (TPPS(4)/sodium salt) anionic, nanoassembled in phospholipid Langmuir monolayers and Langmuir-Blodgett films. Furthermore, we used chitosan to mediate the interaction between the porphyrins and the model membrane, aiming to understand the role of the polysaccharide in a molecular level. The effect of the interaction of the photosensitizers on the fluidity of the lipid monolayer was investigated by using dilatational surface elasticity. We also used photoluminescence (PL) spectroscopy to identify the porphyrins adsorbed in the phospholipid films. We observed an expansion of the monolayer promoted by the adsorption of the porphyrins into the lipid-air interface which was more pronounced in the case of TMPyP, as a consequence of a strong electrostatic interaction with the anionic monolayer. The chitosan promoted a higher adsorption of the porphyrins on the phospholipid monolayers and enabled the porphyrin to stay in its monomeric form (as confirmed by PL spectroscopy), thus demonstrating that chitosan can be pointed out as a potential photosensitizer delivery system in photodynamic therapy.
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This article reports a study on the preparation, densification process, and structural and optical properties of SiO(2)-Ta(2)O(5) nanocomposite films obtained by the sol-gel process. The films were doped with Er(3+) and the Si:Ta molar ratio was 90:10. Values of refractive index, thickness and vibrational modes in terms of the number of layers and thermal annealing time are described for the films. The densification process is accompanied by OH group elimination, increase in the refractive index, and changes in film thickness. Full densification of the film is acquired after 90 min of annealing at 900 degrees C. The onset of crystallization and devitrification, with the growth of Ta(2)O(5) nanocrystals occurs with film densification, evidenced by high-resolution transmission electron microscopy. The Er(3+)-doped nanocomposite annealed at 900 degrees C consists of Ta(2)O(5) nanoparticles, with sizes around 2 nm, dispersed in the SiO(2) amorphous phase. The main emission peak of the film is detected at around 1532 nm, which can be assigned to the (4)I(13/2)->(4)I(15/2) transition of the Er(3+) ions present in the nanocomposites. This band has a full width at half medium of 64 nm, and the lifetime measured for the (4)I(13/2) levels is 5.4 ms, which is broader compared to those of other silicate systems. In conclusion, the films obtained in this work are excellent candidates for use as active planar waveguide. (C) 2010 Elsevier B.V. All rights reserved.
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Layered Double Hydroxides are a class of materials that can be described as positively charged layers of divalent and trivalent cations in the centre of edge-sharing octahedra. Cholesterol derivatives such as cholic acid are substances that play an important role in the digestion of fat components by the organism. This work presents a study on the intercalation of cholate anions in calcined MgAl-CO(3)-HDL. Isotherm experiments were performed at three different temperatures to evaluate the capacity of anion removal by sorption in the calcined LDH. The plateau was reached in all conditions. Increasing temperature results in decreasing cholate sorption. Characteristic peaks of LDH regenerated with OH(-) anions were observed at lower cholate concentrations. A peak in 2 theta equals to 7.5 degrees and peaks between 15 degrees and 20 degrees are observed. Those peaks are the same as the ones observed in the pure sodium cholate PXRD. At higher cholate concentrations the sorbed solids present PXRD related to an additional layered phase, which is related to intercalation of cholate anions with basal spacing equal to 34.3 angstrom. Thus, the cholate anions are also intercalated with a bilayer molecular arrangement at equilibrium concentrations at the isotherms plateau. (C) 2009 Elsevier Ltd. All rights reserved.
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One major challenge for the widespread application of direct methanol fuel cells (DMFCs) is to decrease the amount of platinum used in the electrodes, which has motivated a search for novel electrodes containing platinum nanoparticles. In this study, platinum nanoparticles were electrodeposited on layer-by-layer (LbL) films from TiO(2) and poly(vinyl sulfonic) (PVS), by immersing the films into a H(2)PtCl(6) solution and applying a 100 mu A current during different electrode position times. Scanning tunnel microscopy (STM) and atomic force microscopy (AFM) images showed increased platinum particle size and electrode roughness for increasing electrodeposition times. The potentiodynamic profile of the electrodes indicated that oxygen-like species in 0.5 mol L(-1) H(2)SO(4) were formed at less positive potentials for the smallest platinum particles. Electrochemical impedance spectroscopy measurements confirmed the high reactivity for the water dissociation and the large amount of oxygen-like species adsorbed on the smallest platinum nanoparticles. This high oxophilicity of the smallest nanoparticles was responsible for the electrocatalytic activity of Pt-TiO(2)/PVS systems for methanol electrooxidation, according to the Langmuir-Hinshelwood bifunctional mechanism. Significantly, the approach used here combining platinum electrodeposition and LbL matrices allows one to both control the particle size and optimize methanol electrooxidation, being therefore promising for producing membrane-electrode assemblies of DMFCs.
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Layered Double Hydroxides are a class of materials that can be described as positively charged planar layers consisting of divalent and trivalent cations in the center of edge-sharing octahedra. The positive charge in the LDH layers must be compensated by anion intercalation. These materials have applications that include adsorption and/or sorption of anionic species. Cholic acid is one of the main acids produced by the liver. It promotes transport of lipids through aqueous systems. This work reports on the adsorption of Cholic acid anions in MgAl-CO3-LDH taking ionic strength, pH, and temperature effects into account. The adsorbent was characterized by different techniques. Cholate anion adsorption was performed at two different temperatures (298 and 323 K), two different ionic strength conditions (0.0 and 0.1 M of NaCl), and two different pH values (7.0 and 10.0). The results show that the sorption of Cholate anions in calcined LDH can remove a considerable amount of these anions from the medium. Cholate anion adsorption in the LDH with no calcining also occurs, but at a lower amount.
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In this work we report the adsorption of phenylalanine (Phe) on Magnesium Aluminum Layered Double Hydroxides (Mg-Al-CO(3)-LDH) at two different temperatures (298 and 310 K) and under two distinct ionic strength conditions (with and without the addition 0.1 M of NaCl). The adsorption isotherms exhibit the same profile in all conditions, and they only differ in the amount of removed Phe. At lower ionic strength, the isotherms are almost identical at both temperatures, except for the last points, where the increase in temperature causes a decrease in the amount of adsorbed Phe. An increase in ionic strength results in a decrease in Phe adsorption. The electrokinetic potential decreases as the amount of adsorbed Phe increases, and only positive values are observed. This indicates that the surface of the adsorbent is not totally neutralized and suggests that more Phe could be removed by adsorption. The presence of Phe on the solid is confirmed by FTIR spectra, which present the specific bands assigned to Phe. The hydrophobicity of the amino acid probably contributes to its extraction, thus enabling the removal of a great amount of Phe. In conclusion, LDH is potentially applicable in the removal of Phe from wastewater.
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The mineralogy and origin of micas were investigated in incipient soils surrounding a modem alkaline-saline lake of Nhecolandia, a sub-region of Pantanal wetland. Soils were sampled along a toposequence and analyzed by XRD, TEM-EDS, and ICP-MS. The studied micas, mainly concentrated in a green horizon, are dioctahedral, strongly associated with Fe(3+) and Al, and interstratified with smectite layers. Classification of individual crystals shows that glauconite and Fe-illite are the dominant micas, but one crystal of illite was recognized. Si-rich amorphous materials are associated with small crystallites in the mica-enriched horizon. A recent study shows that water samples from the studied lake and the surrounding water table have high pH, negative Eh, temperatures up to 40 C. high concentration of K. and low concentration of Si(OH)(4). Experimental studies of micas synthesis reported in the literature show that similar water conditions allow for dioctahedral mica crystallization from initial precipitation of amorphous hydroxides. Therefore, water characteristics combined with presence of Si-rich amorphous materials in the mica-enriched horizon suggest that the micas of the study area are neoformed. The alternated origin of illite, glauconite, and Fe-illite mixed-layer minerals probably occurs due to seasonal variations of pH. temperature, and chemical composition of waters in microenvironments, since the changes at this scale are possibly faster and more extreme. (C) 2010 Elsevier B.V. All rights reserved.
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Aims: To analyse the expression of three homeobox genes (HOXA7, PITX1 and PRRX1) in oral squanous cell carcinomas (OSCC) and the relationship of such expression to certain distinct histopathological features of OSCC and in comparison to adjacent non-neoplastic epithelium (NT). Methods and results: Digoxigenin-labelled riboprobes that are specific for each homeobox gene were generated and in situ hybridization was carried out on frozen sections. In NT samples, HOXA7 and PITX1 transcripts were found more frequently in all epithelial layers, while PRRX1 was expressed in the basal layer. With OSCC samples, expression of the three genes was associated with all histological features. However, the HOXA7 and PITX1 signals were more intense in sheets and nests and PRRX1 in small nests and isolated cells. Conclusion: HOXA7, PIXT1 and PRRX1 homeobox genes have different patterns of expression in OSCC depending on its histological features.
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Protrusion of the abdominal wall secondary to abdominoplasty may occur in patients with weakness of the aponeurotic structures. The anterior layer of the rectus abdominis muscle consists of fibers that are transverse rather than vertical. Based on this anatomical feature, vertical sutures are suggested for the correction of diastasis recti, since they include a greater amount of fascial fibers and thus would be more resistant to tensile strength than horizontal ones. The anterior layers of the rectus abdominis muscles of 15 fresh cadavers were dissected. Two vertical lines were marked on each side of the linea alba, corresponding to the site where plication is usually performed in abdominoplasties. Three abdominal levels were evaluated: the supraumbilical, umbilical, and infraumbilical levels. A simple suture was placed in the vertical direction in one group and in the horizontal direction in the other group, at each of the three levels previously described. These sutures were connected to a dynamometer, which was pulled medially toward the linea alba until rupture of the aponeurosis occurred. The mean strength required to rupture the aponeurotic structures in which the vertical sutures had been placed was greater than for the horizontal ones (p < 0.0001). The vertical suture of the rectus abdominis sheaths was stronger than the horizontal suture because of the more transversal arrangement of its aponeurotic fibers. Thus, routine use of the vertical suture in plications of the aponeurosis of the rectus abdominis muscles is suggested.
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Purpose: The bladder is normally impermeable to possible hostile environmental factors and toxic urinary wastes. Any disruption of the permeability barrier would permit the leakage of urine constituents into the underlying cells layers and subsequent inflammation. Protamine sulfate, which increases urothelial permeability, is used in experimental models of cystitis. We examined whether protamine sulfate alone could cause bladder inflammation or if the association of protamine sulfate and urine is needed for this condition. Materials and Methods: Female Wistar rats (Center for the Development of Experimental Models for Medicine and Biology, Federal University of Sao Paulo, Sao Paulo, Brazil) had the bladder catheterized and instilled with protamine sulfate (10 mg) or sterile saline for 30 minutes. To exclude urine other groups of rats underwent bilateral nephrectomy and the same procedure was used. One day after instillation the bladders were removed for histopathology. Edema and vascular congestion were graded from 0-none to 3-severe. Polymorphonuclear and mast cells were counted. The Kruskal-Wallis test was performed for statistical analysis. Results: Intravesical instillation of protamine sulfate in nonnephrectomized rats led to inflammation, in contrast to findings in rats instilled with saline. On the other hand, nephrectomized rats showed no inflammatory changes following the instillation of protamine sulfate or saline. The mast cell count was similar in all groups. Conclusions: Bladder inflammation in this experimental model of urothelial injury was not due to protamine sulfate alone. The association of protamine sulfate and urine was necessary to trigger the inflammatory cascade. Thus, urine indeed has an important role in the development of bladder inflammation in an environment of higher urothelial permeability.
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The present study aimed to verify the time course of the effects of environmental levels of urban air pollution toxicity on lung arterioles. BALB/c mice (n = 56) were continuously exposed to selective chambers equipped with (filtered, F) or without (non-filtered, NF) filter devices for particles and toxic gases for 24 h/day, over 14, 21, 30 or 45 days. After exposure, we evaluated the lumen-wall relationship (an estimator of arteriolar narrowing), endothelial nitric oxide synthase (eNOS) and endothelin type A receptor (ETAr) expression in the vascular wall and inflammatory influx of the peribronchiolar area. Concentrations of fine particulate matter (PM <= 2.5 mu g/m(3)), nitrogen dioxide (NO(2)), black smoke (BS), humidity and temperature in both the environment and inside the chambers were measured daily. Filters cleared 100% of BS and 97% of PM inside the F chamber. The arteriole wall of the lungs of mice from NF chamber had an increased ETAr expression (p <= 0.042) concomitant to a decrease in the lumen/wall ratio (p = 0.02) on the early days of exposure, compared to controls. They also presented a progressive increment of inflammatory influx in the peribronchiolar area during the study (p = 0.04) and decrement of the eNOS expression on the 45th day of exposure in both vascular layers (p <= 0.03). We found that after 14 days of exposure, the ambient levels of air pollutants in Sao Paulo induced vasoconstriction that was associated with an increase in ETAr expression. These vascular results do not appear to be coupled to the progressive inflammatory influx in lung tissue, suggesting a down-regulation of vasoconstrictive mechanisms through an imbalance in the cytokines network. It is likely that these responses are protective measures that decrease tissue damage brought about by continuous exposure to air pollutants. (C) 2010 Elsevier Inc. All rights reserved.
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Background Molluscum contagiosum (MC) is a Molluscipox virus infection of keratinocytes with hyperplasia and intracytoplasmic inclusions-the molluscum bodies (MBs). Few papers address cytokeratins (K) profile in MC, mainly focusing terminal keratinization process. Methods Forty-one MC lesions were subjected to immunohistochemical technique to verify K1, K10, K14, K16, involucrin, filaggrin, E-cadherin and p63 expression. MC immunolabeling pattern was compared to adjacent normal appearing epidermis (ANAE). Results In MC and ANAE, K1/K10 were expressed in suprabasal layers, K14 was expressed in basal and suprabasal layers and K16 was expressed through all spinous layer. Involucrin and filaggrin were observed in granular, spinous and in basal layer of ANAE and MC. E-cadherin was present up to the first layers of MC while ANAE exhibited E-cadherin labeling at basal and spinous layers. Basal and spinous layers keratinocytes nuclei, in both MC and ANAE, express p63. Conclusion Infection by Molluscipox virus alters keratinocyte differentiation status. The presence of K14 and p63 in spinous layer, as well as early expression of involucrin and filaggrin, associated to a hyperproliferative state disclosed by K16 expression, may be a result of disruption in keratinocytes maturation process. The changes observed at ANAE may represent early events in keratinization disturbance. Callegaro CF, Sotto MN. Molluscum contagiosum: immunomorphological aspects of keratinocytes markers of differentiation and adhesion.
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Background: Epidermodysplasia verruciformis (EV) is a rare genodermatosis with susceptibility to human papillomavirus (HPV) infection, and high risk of skin cancer considered a model of viral oncogenesis. Methods: Fifteen cases of EV plane wart (PW)-type lesions (EV) and 14 cases of PW in healthy individuals were subjected to immunohistochemical technique for cytokeratins (K) 1, 10, 14, 16, 4, involucrin, filaggrin and e-cadherin. Results: K1/10 showed retarded or negative expression in EV, being substituted by K14. Expression of K14 occurred in the basal and suprabasal layers in both groups, but in EV, its expression was observed up to the more superficial layers. Both groups showed positivity for K16 and K4, involucrin expression in lower levels of the spinous layer and unaltered filaggrin expression. E-cadherin expression was diminished at the koilocytotic foci of both lesions, more superficially in EV. Conclusion: Infection by HPV may alter the differentiation status of the epidermis, leading to a major expression of K14, delayed or absent expression of K1/10 and earlier involucrin expression, especially in EV. It also stimulates the expression of K16 and K4. Filaggrin expression is not altered, and e-cadherin is diminished in superficial koilocytotic cells` foci in EV.
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This paper analyzes the astroglial and neuronal responses in subtelencephalic structures, following a bilateral ablation of the telencephalon in the Columba livia pigeons. Control birds received a sham operation. Four months later the birds were sacrificed and their brains processed for glial fribillary acid protein (GFAP) and neurofilament immunohistochemistry, markers for astrocytes and neurons, respectively. Computer-assisted image analysis was employed for quantification of the immunoreactive labeling in the nucleus rotundus (N.Rt) and the optic tectum (OT) of the birds. An increased number of GFAP immunoreactive astrocytes were found in several subregions of the N.Rt (p .001), as well as in layers 1, 2cd, 3, and 6 of the OT (p .001) of the lesioned animals. Neurofilament immunoreactivity decreased massively in the entire N.Rt of the lesioned birds; however, remaining neurons with healthy aspect showing large cytoplasm and ramified branches were detected mainly in the periphery of the nucleus. In view of the recently described paracrine neurotrophic properties of the activated astrocytes, the data of the present study may suggest a long-lasting neuroglial interaction in regions of the lesioned bird brain far from injury. Such events may trigger neuronal plasticity in remaining brain structures that may lead spontaneous behavior recovery as the one promoted here even after a massive injury.
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Study Objective: To estimate the relationship between the depth of lesions of rectal endometriosis and the percentage of the circumference of the bowel segment affected by the disease. Design: A prospective pathologic analysis of 45 surgical specimens of bowel endometriosis obtained by laparoscopic segmental resection of the rectosigmoid (Canadian Task Force classification II-1). Setting: Tertiary referral hospital. Patients: forty-five patients were submitted to a segmental resection of the rectum due to endometriosis between July 2004 and September 2006. Interventions: Morphometric aspects of endometriotic lesions were analyzed, such as size and thickness of the lesion, deepest layer of bowel affected by lesion, and percentage of circumference of bowel affected by endometriosis. Measurements and Main Results: Results showed that in lesions that reached the submucous layer of the bowel, the circumference affected was 31.6% greater than in lesions that reached only the outer muscular layer, whereas in lesions that reached the mucous layer, the circumference affected was 52.5% greater than in those that reached the outer muscular layer of the bowel. In addition, 89.3% of lesions with an affected circumference greater than 40% were those affecting the submucous or mucous layers of the bowel. These results suggest that when a lesion reaches these 2 deepest layers of the rectosiamoid, risk increases that the circumference affected will be greater than 40% (relative risk = 1.5; 95% CI: 1.0-2.3; p =.03). Conclusion: In endometriotic lesions affecting the rectosigmoid beyond the inner muscular layer of the bowel wall, more than 40% of the circumference of the rectosigmoid is affected by the disease, confirming the recommendation of segmental resection of the bowel for this form of the disease.