A relevante potencialidade dos centros básicos nitrogenados disponíveis em polímeros inorgânicos e biopolímeros na remoção catiônica

This review reports the application of inorganic and organic polymeric materials for cation removal by using nitrogenated basic centers. The data demonstrate the importance of the desired groups when free or immobilized on natural or synthesized inorganic polymers through silanol groups. Thus, the most studied silica gel is followed by natural crysotile and talc polymers, and the synthesized mesopore silicas, talc-like, silicic acids, phosphates and phyllosilicates. The organic natural biopolymeric chitin and cellulose were chemically modified to improve the availability of the amine groups or the reactivity with desirable molecules to enlarge the content of basic centers. The cation removal takes place at the solid/liquid interface and some interactive effects have their thermodynamic data determined.

The syntheses of the marine metabolites 3-bromoverongiaquinol and 5-monobromocavernicolin

An efficient synthesis of the marine metabolite 3-bromoverongiaquinol (1) and the first total synthesis of 5-monobromocavernicolin (2), both isolated from the marine sponge Aplysina cavernicola, have been described based on the 1,2 addition of the lithium enolate of N,O-bistrimethylsilylacetamide (BSA, 4) to 1,4-benzoquinone (3). Bromination and purification of the crude product on silica gel chromatography provided 3-bromoverongiaquinol (1) in 50% overall yield. Under alkaline conditions, the crude product of the bromination reaction was converted to 5-monobromocavernicolin (2) in 20% yield which was also obtained in 13% yield (25% yield based on recovered starting material) from 3-bromoverongiaquinol (1).

Hidrocarbonetos aromáticos policíclicos em margarina, creme vegetal e maionese

Polycyclic aromatic hydrocarbons (PAHs) are a group of compounds that have been the subject of much concern due to their toxic potential. In this study, margarine?s, vegetable cream and mayonnaise available on the Brazilian market were analyzed for pyrene, chrysene, benzo(a)pyrene, benzo(b)fluoranthene and dibenzo(a,h)anthracene. The analytical methodology involved liquid-liquid extraction, clean-up on silica gel column and determination by high performance liquid chromatography using fluorescence detector. Variable levels of contamination were found within differents brands of the same product and within differents batches of the same brand. The total PAH content was in the range of 4.1 to 7.1mug/kg in vegetable cream, 1.7 to 3.9mug/kg in margarine and 1.0 to 21.7mug/kg in mayonnaise. In general the products which according to the label contain corn oil showed the highest levels of contamination. Based on these results and on the importance of fat, oils and derived products for the intake of PAHs, it is recommended that producers of margarine, vegetable creams and mayonnaise start to control the contamination of the vegetable oils used in the elaboration of these products, in order to reduce the exposure of consumers to excessive amounts of potentially carcinogenic compounds.

Autologous Platelet Gel: Five Cases Illustrating Use On Sickle Cell Disease Ulcers.

Leg ulcers represent a particularly disabling complication in patients with sickle cell disease (SCD). Platelet gel (PG) is a novel therapeutic strategy used for accelerating wound healing of a wide range of tissues through the continuous release of platelet growth factors. Here, we describe the use of PG preparation according to Anitua's PRGF (preparations rich in growth factors) protocol for treating chronic nonhealing ulcers in patients with SCD. A positive response occurred in 3 patients with an area reduction of 85.7% to 100%, which occurred within 7 to 10 weeks, and a 35.2% and 20.5% of area reduction in 2 other patients, who however, had large ulcers. After calcium chloride addition, the platelet-rich plasmas demonstrated enhanced platelet-derived growth factors-BB (P < .001), transforming growth factor-β1 (P = .015), vascular endothelial growth factors (P = .03), and hepatocyte growth factors (nonsignificant) secretion. Furthermore, calcium chloride addition induced a significant decrease in platelet number (P = .0134) and there was no leukocyte detection in the PG product. These results demonstrate that PG treatment might impact the healing of leg ulcers in sickle cell disease, especially in patients with small ulcers.

Microbial Evaluation Of Traumatized Teeth Treated With Triple Antibiotic Paste Or Calcium Hydroxide With 2% Chlorhexidine Gel In Pulp Revascularization.

Revascularization outcome depends on microbial elimination because apical repair will not happen in the presence of infected tissues. This study evaluated the microbial composition of traumatized immature teeth and assessed their reduction during different stages of the revascularization procedures performed with 2 intracanal medicaments. Fifteen patients (7-17 years old) with immature teeth were submitted to the revascularization procedures; they were divided into 2 groups according to the intracanal medicament used: TAP group (n = 7), medicated with a triple antibiotic paste, and CHP group (n = 8), dressed with calcium hydroxide + 2% chlorhexidine gel. Samples were taken before any treatment (S1), after irrigation with 6% NaOCl (S2), after irrigation with 2% chlorhexidine (S3), after intracanal dressing (S4), and after 17% EDTA irrigation (S5). Cultivable bacteria recovered from the 5 stages were counted and identified by means of polymerase chain reaction assay (16S rRNA). Both groups had colony-forming unit counts significantly reduced after S2 (P < .05); however, no significant difference was found between the irrigants (S2 and S3, P = .99). No difference in bacteria counts was found between the intracanal medicaments used (P = .95). The most prevalent bacteria detected were Actinomyces naeslundii (66.67%), followed by Porphyromonas endodontalis, Parvimonas micra, and Fusobacterium nucleatum, which were detected in 33.34% of the root canals. An average of 2.13 species per canal was found, and no statistical correlation was observed between bacterial species and clinical/radiographic features. The microbial profile of infected immature teeth is similar to that of primarily infected permanent teeth. The greatest bacterial reduction was promoted by the irrigation solutions. The revascularization protocols that used the tested intracanal medicaments were efficient in reducing viable bacteria in necrotic immature teeth.

Improved Selective Cholesterol Adsorption By Molecularly Imprinted Poly(methacrylic Acid)/silica (pmaa-sio₂) Hybrid Material Synthesized With Different Molar Ratios.

The present paper describes the synthesis of molecularly imprinted polymer - poly(methacrylic acid)/silica and reports its performance feasibility with desired adsorption capacity and selectivity for cholesterol extraction. Two imprinted hybrid materials were synthesized at different methacrylic acid (MAA)/tetraethoxysilane (TEOS) molar ratios (6:1 and 1:5) and characterized by FT-IR, TGA, SEM and textural data. Cholesterol adsorption on hybrid materials took place preferably in apolar solvent medium, especially in chloroform. From the kinetic data, the equilibrium time was reached quickly, being 12 and 20 min for the polymers synthesized at MAA/TEOS molar ratio of 6:1 and 1:5, respectively. The pseudo-second-order model provided the best fit for cholesterol adsorption on polymers, confirming the chemical nature of the adsorption process, while the dual-site Langmuir-Freundlich equation presented the best fit to the experimental data, suggesting the existence of two kinds of adsorption sites on both polymers. The maximum adsorption capacities obtained for the polymers synthesized at MAA/TEOS molar ratios of 6:1 and 1:5 were found to be 214.8 and 166.4 mg g(-1), respectively. The results from isotherm data also indicated higher adsorption capacity for both imprinted polymers regarding to corresponding non-imprinted polymers. Nevertheless, taking into account the retention parameters and selectivity of cholesterol in the presence of structurally analogue compounds (5-α-cholestane and 7-dehydrocholesterol), it was observed that the polymer synthesized at the MAA/TEOS molar ratio of 6:1 was much more selective for cholesterol than the one prepared at the ratio of 1:5, thus suggesting that selective binding sites ascribed to the carboxyl group from MAA play a central role in the imprinting effect created on MIP.

Recolonization Of Mutans Streptococci After Application Of Chlorhexidine Gel.

Streptococcus mutans is specifically suppressed by intensive treatment with chlorhexidine gel, but the time for recolonization and the effect on other oral bacteria are not totally clear. In this study, recolonization of mutans streptococci was evaluated in nine healthy adult volunteers, who were highly colonized with this microorganism. Stimulated saliva was collected before (baseline) and at 1, 7, 14, 21 and 28 days after application of 1% chlorhexidine gel on volunteers' teeth for two consecutive days. On each day, the gel was applied using disposable trays for 3 x 5 min with intervals of 5 min between each application. Saliva was plated on blood agar to determine total microorganisms (TM); on mitis salivarius agar to determine total streptococci (TS) and on mitis salivarius agar plus bacitracin to determine mutans streptococci (MS). Chlorhexidine was capable of reducing the counts of MS and the proportion of MS with regard to total microorganisms (%MS/TM) (p<0.05), but these values did not differ statistically from baseline (p>0.05) after 14 days for MS and 21 days for %MS/TM. The counts of TM and TS and the proportion of MS to total streptococci did not differ statistically from baseline (p>0.05) after chlorhexidine treatment. The results suggest that the effect of chlorhexidine gel treatment on suppression of mutans streptococci is limited to less than a month in highly colonized individuals.

Lymphocyte Activation In Silica-exposed Workers.

Exposure to silica dust has been examined as a possible risk factor for autoimmune diseases, including systemic sclerosis, rheumatoid arthritis, systemic lupus erythematosus and ANCA-associated vasculitis. However, the underlying cellular and molecular mechanisms resulting in the increased prevalence of autoimmunity remain elusive. To clarify these mechanisms, we studied various markers of immune activation in individuals occupationally exposed to silica dust, i.e., serum levels of soluble IL-2 receptor (sIL-2R), levels of IL-2, other pro- and anti-inflammatory cytokines and lymphoproliferation. Our results demonstrate that silica-exposed individuals present important alterations in their immune response when compared to controls, as shown by increased serum sIL-2R levels, decreased production of IL-2 and increased levels of the pro-inflammatory (IFN-γ, IL-1α, TNF-α, IL-6) as well as anti-inflammatory (IL-10 and TGF-β) cytokines. Furthermore, silica-exposed individuals presented enhanced lymphoproliferative responses. Our findings provide evidence that the maintenance of immune homeostasis may be disturbed in silica-exposed individuals, possibly resulting in autoimmune disorders.

Liposomal Lidocaine Gel For Topical Use At The Oral Mucosa: Characterization, In Vitro Assays And In Vivo Anesthetic Efficacy In Humans.

To characterize liposomal-lidocaine formulations for topical use on oral mucosa and to compare their in vitro permeation and in vivo anesthetic efficacy with commercially available lidocaine formulations. Large unilamellar liposomes (400 nm) containing lidocaine were prepared using phosphatidylcholine, cholesterol, and α-tocoferol (4:3:0.07, w:w:w) and were characterized in terms of membrane/water partition coefficient, encapsulation efficiency, size, polydispersity, zeta potential, and in vitro release. In vitro permeation across pig palatal mucosa and in vivo topical anesthetic efficacy on the palatal mucosa in healthy volunteers (double-blinded cross-over, placebo controlled study) were performed. The following formulations were tested: liposome-encapsulated 5% lidocaine (Liposome-Lido5); liposome-encapsulated 2.5% lidocaine (Liposome-Lido2.5); 5% lidocaine ointment (Xylocaina®), and eutectic mixture of lidocaine and prilocaine 2.5% (EMLA®). The Liposome-Lido5 and EMLA showed the best in vitro permeation parameters (flux and permeability coefficient) in comparison with Xylocaina and placebo groups, as well as the best in vivo topical anesthetic efficacy. We successfully developed and characterized a liposome encapsulated 5% lidocaine gel. It could be considered an option to other topical anesthetic agents for oral mucosa.

Síntese e estudo de ortossilicatos de zinco luminescentes com aplicação da técnica sol-gel

Usually, the concepts of the Sol-Gel technique are not applied in experimental chemistry courses. This work presents a feasible experiment for chemistry instruction, which involves the synthesis of luminescent materials - Zn2SiO4, with and without Mn2+ as a dopant - by the Sol-Gel technique. The obtained materials were analyzed by scanning electron microscopy, X-Ray diffraction, IR spectroscopy and luminescence measures by UV-vis spectroscopy. The results allow the students to confirm the luminescent properties of the zinc orthosilicate luminophores as well as the structural features expected from literature data.

CROMATOGRAFIA DE AFINIDADE COM CORANTE RED A versus TROCA IÔNICA-PERMEABILIDADE EM GEL: COMPARAÇÃO DA PRATICIDADE NA PURIFICAÇÃO DE ENTEROTOXINA ESTAFILOCÓCICA A

Culture supernatant of Staphylococcus aureus 722 in 3% triptone plus 1% yeast extract was used for EEA purification, proceeding comparison between dye ligand Red A affinity chromatography and classic chromatography. The capture of SEA with Amberlite CG-50 allowed rapid enterotoxin concentration from the culture supernatant. However, the ratio of 15 mg of the resin to a total of 150 mg of the toxin satured the resin, giving only 10 to 30% of SEA recuperation from the supernatant. The elution of concentrated material throught the Red A column resulted in a recovery of 60,87% of the toxin, and required 76 hours, indicating advantage on classic chromatography. Ion exchange column plus gel filtration recovered only 6,5 % of the SEA, and required 114 hours to conclude the procedure. The eletrophoresis of purified SEA indicated high grade of toxin obtained from Red A column, with 90 % of purity, compared to 60 % of classic column.