José Pedrazzoli Júnior

Avaliação do dano oxidativo ao DNA de células normais e neoplásicas da mucosa cólica de doentes com câncer colorretal

Oxidative stress on mucosal cells of the colon, resulting from the action of free radicals present in the intestinal lumen, represents one of the initial phenomena in colorectal carcinogenesis, because it may induce gene mutations relating to cell cycle control. Quantification of the oxidative damage to the DNA in colorectal cancer patients has been little studied so far. OBJECTIVE: To measure the levels of oxidative damage to the DNA in cells isolated from the colon mucosa in colorectal patients, and to compare normal and neoplastic tissues and make correlations with anatomopathological variables. METHOD: Thirty colorectal adenocarcinoma patients (eighteen women) of mean age 60.6 ± 15.5 years who consecutively underwent operations performed by the same surgical team between 2005 and 2006 were studied. The oxidative damage to the DNA was evaluated by means of the alkaline version of the comet assay (single-cell gel electrophoresis), from fragments of normal and neoplastic colon tissue that were obtained immediately after removal of the surgical specimen. The extent of breakages of the DNA helices was assessed using an image intensification method, on 200 randomly chosen cells (100 from each tissue sample), by means of the Komet 5.5 program. The Tail Moment (T.M) measured in each cell quantitatively represented the extent of the oxidative damage to the DNA. The statistical analysis on the variables considered was performed by means of the Student t, chi-squared and Kruskal-Wallis tests, with a significance level of 5% (p<0.05). RESULTS: It was found that, for all the patients studied, the cells obtained from the neoplastic tissue presented oxidative damage to the DNA that was greater than in the cells from normal tissue. The cells isolated from the neoplastic mucosal tissue of the colon presented extension of DNA strand breakage significantly greater (T.M. = 2.532 ± 0.945) than did the cells isolated from normal tissue (T.M. = 1.056 ± 0.460) (p=0.00001; C.I. 95%: -1.7705 to -1.1808). It was found that the patients at earlier stages of the Dukes and TNM classifications presented higher levels of oxidative damage than did those at more advanced stages (p=0.04 and p=0.001, respectively). CONCLUSIONS: The cells obtained from normal tissue of colorectal cancer patients presented signs of oxidative damage to the cell DNA, although at significant lower levels than in the neoplastic cells.

Pharmacokinetic and local toxicity studies of liposome-encapsulated and plain mepivacaine solutions in rats

The pharmacokinetics and the local toxicity of commercial and liposome-encapsulated mepivacaine formulations injected intra-orally in rats were studied. Animals were divided in groups (n = 4–6) and treated with 0.1 mL of the formulations: 2% mepivacaine with 1:100,000 epinephrine (MVC2%EPI), 3% mepivacaine (MVC3%), and 2% liposome-encapsulated mepivacaine (MVCLUV). The results showed that the 2% liposome-encapsulated mepivacaine reduced Cmax, prolonged AUC0–∞ and t1/2 compared with 3% plain and 2% vasoconstritor-associated mepivacaine, after intraoral injection. In addition, it was also observed that liposomal mepivacaine might protect the tissue against local inflammation evoked by plain or vasoconstrictors-associated mepivacaine, giving supporting evidence for its safety and possible clinical use in dentistry.

Pharmacokinetic study of liposome-encapsulated and plain mepivacaine formulations injected intra-orally in volunteers.

Objectives  The pharmacokinetics of commercial and liposome‐encapsulated mepivacaine (MVC) injected intra‐orally in healthy volunteers was studied.

Expression of Toll-Like Receptors in Enterocromaffin-Like Cells and Their Function in Histamine Release

IntroductionEnterocromaffin-like cells (ECL) are specialized endocrine gastric cells able to release histamine, which in turn controls gastric acid production by parietal cells. Helicobacter pylori infection and other conditions signal in the gastrointestinal tract via Toll-like receptors (TLRs) and modify gastric acid production, but there is no evidence of expression and function of TLRs in ECL cells. In this work, we analyzed gene and protein expression of TLR-2, 4, 5, and 9, and other molecules involved in TLR signaling in ECL cells.Material and MethodsECL cells were isolated from Sprague–Dawley rats. The histamine-releasing ability of TLR ligands was also evaluated after culture of the ECL cells for a short time.ResultsWith ECL cells that expressed the TLR-2, TLR-4, TLR-5, and TLR-9 genes we were able to confirm protein expression for TLR-2, TLR-5, and TLR-9. Functionally, ECL cells were able to release histamine in response to TLR-2 stimulation by peptidoglycan (PGN), a TLR-2 ligand. After PGN stimulus, IRAK and p38 phosphorylation could be observed. SB 203580, a p38 inhibitor, reversed PGN-induced histamine release. Lipopolysaccharide (LPS), a TLR-4 ligand, was also able to induce histamine release in ECL cells, but by a mechanism independent of TLRs.ConclusionsWe have demonstrated for the first time that ECL cells express TLRs and respond to TLR-2 ligand by increasing histamine release. This response could be involved in host defense against gastrointestinal bacterial pathogens but could also contribute to control of gastric acid secretion in the absence of pathogens.

Bupivacaine in alginate and chitosan nanoparticles: an in vivo evaluation of efficacy, pharmacokinetics, and local toxicity

Objective This study reports a preclinical evaluation of an alginate/chitosan nanoparticle formulation containing NovaBupi®, a racemic bupivacaine (BVC) containing 25% dextrobupivacaine and 75% levobupivacaine. Methods New Zealand White rabbits (n=6) received intraoral or intrathecal injections of BVC 0.5% or BVC 0.5%-loaded alginate–chitosan nanoparticles (BVCALG). BVC plasma levels and pharmacokinetic parameters were determined in blood samples of these rabbits. An infraorbital nerve blockade was performed in male Wistar rats (n=7) with the same formulations and the vehicle (NPALG). Histological evaluation of local toxicity after 6 hours and 24 hours of the treatments was performed in rats’ (n=6) oral tissues. Results No statistically significant difference was observed between plasma concentrations and pharmacokinetic parameters (p>0.05) after intraoral injections. However, after intrathecal injection BVCALG changed approximately three times the values of volume of distribution and area under the curve (AUC0–t; p<0.05). The total analgesic effect of BVC after infraorbital nerve blockade was improved by 1.4-fold (p<0.001) with BVCALG. BVC and BVCALG did not induce significant local inflammatory reaction. Conclusion The encapsulation of BVC prolongs the local anesthetic effect after infraorbital nerve blockade and altered the pharmacokinetics after intrathecal injection.

Carvacryl acetate, a novel semisynthetic monoterpene ester, binds to the TRPA1 receptor and is effective in attenuating irinotecan‐induced intestinal mucositis in mice

We aimed to determine whether carvacryl acetate acts as a TRPA1 receptor agonist and its effects against irinotecan (CPT‐11) induced intestinal mucositis in mice.