Patrícia Gomes

A simple and inexpensive automated technique for measurement of serum nitrite/nitrate

OBJECTIVE We described an automated technique for measurement of serum nitrite/nitrate (NO(x)) using the Cobas Mira clinical chemistry analyzer. DESIGN AND METHODS NO(x) was measured by the modified Griess method. Precision, accuracy, linearity, instrument carry-over and lower limit of quantitation (LLOQ) were assessed. RESULTS The automated technique for measurement of serum NO(x) was linear, precise, and accurate. It has a LLOQ of 2.0 μmol/L. CONCLUSION Serum NO(x) measured by the modified Griess method can be applied easily to the Cobas Mira clinical chemistry analyzer.

Trypanocidal action of tea tree oil (Melaleuca alternifolia) against Trypanosoma evansi in vitro and in vivo used mice as experimental model

This study aimed to evaluate the Trypanosoma evansi susceptibility to tea tree oil (TTO - Melaleuca alternifolia) and tea tree oil nanocapsules (TTO nanocapsules) in vitro and in vivo tests. In vitro, we observed a mortality curve of trypomastigotes proportional to dose, i.e., the TTO and TTO nanocapsules have trypanocidal effect. Treatment with TTO in vivo was assessed in experiments (I and II). For Experiment I, T. evansi infected mice were treated with TTO and/or combinations of essential oil with chemotherapy (diminazene aceturate - D.A.). Treatment with TTO at a dose of 1mLkg(-1) was able to extend animal longevity, but had no curative efficacy. However, when TTO was combined with D.A. a disease curative efficacy of 100% for disease was observed, a much better result than the D.A. treatment (33.3%). In Experiment II, T. evansi infected mice were treated with TTO nanocapsules with doses of 0.3, 0.6 and 0.9mLkg(-1). Animals treated with 0.9mLkg(-1) showed higher longevity however without curative effect. Active compounds present in natural products, such as M. alternifolia, may potentiate the treatment of trypanosomosis when associated with other trypanocidal drugs.

Experimental Performance Study of a Very High Speed Free Space Optics Link at the University of Beira Interior Campus: a Case Study

A very high speed FSO (free space optics) link has been successfully implemented for purposes of high requirement applications, at the University Campus. An experimental performance evaluation of this link has been carried out at various OSI levels (1, 4, and 7). Several results are presented and discussed.

An Alternative Pathway Through the Fenton Reaction for the Formation of Advanced Oxidation Protein Products, a New Class of Inflammatory Mediators

The accumulation of advanced oxidation protein products (AOPPs) has been linked to several pathological conditions, and their levels are formed during oxidative stress as a result of reactions between plasma proteins and chlorinated oxidants produced by myeloperoxidase (MPO). However, it was suggested that the generation of this mediator of inflammation may also occur via an MPO-independent pathway. The aim of this study was to induce the formation of AOPPs in vitro through Fenton reaction and to investigate whether this generation could be counteracted by N-acetylcysteine (NAC) and fructose-1,6-bisphosphate (FBP). The complete Fenton system increased the AOPPs levels and both NAC and FBP were capable of inhibiting the formation of Fenton reaction-induced AOPPs. These data provide a new hypothesis about another pathway of AOPPs formation, as well as report that NAC and FBP may be good candidates to neutralize pro-inflammatory and pro-oxidant effects of AOPPs in several diseases.

Fructose-1,6-Bisphosphate and N-Acetylcysteine Attenuate the Formation of Advanced Oxidation Protein Products, a New Class of Inflammatory Mediators, In Vitro

The accumulation of advanced oxidation protein products (AOPP) has been linked to several pathological conditions. Previous studies have identified AOPP as a novel biomarker of oxidative damage to proteins and a novel class of mediator of inflammation. The aim of this study was to determine the effects of fructose-1,6-bisphosphate (FBP) and N-acetylcysteine (NAC) as well as the synergistic effect of both treatments on the formation of AOPP in vitro. For this purpose, we incubated the human serum albumin (HSA) with various hypochlorous acid (HOCl) concentrations to produce albumin-advanced oxidation protein products (HSA-AOPP). Both FBP and NAC were capable of inhibiting the formation of HOCl-induced AOPP in a concentration-dependent manner. The synergistic effect promoted by the association of these drugs showed to be more effective than when tested alone. Thus, both FBP and NAC may be good candidates to mitigate and neutralize pro-inflammatory and pro-oxidant effects of AOPP in several diseases.

Antimycobacterial and antifungal activities of Melaleuca alternifolia oil nanoparticles

Tea tree oil (TTO), derived from M. alternifolia, has been widely used as an antimicrobial agent. Nanoparticles show completely new or improved properties based on specific characteristics such as particle size, distribution, and morphology. It can also enhance the stability of the oil, preventing or reducing the volatilization. In this way, the antimicrobial activities of TTO nanoparticles were evaluated against six Mycobacterium and eleven fungal species. TTO and TTO nanoparticles were active against both bacteria and fungi with MICs ranged from 0.002 to 2.5 %. The results showed that TTO nanoencapsulation maintains TTO activity, indicating that the use of nanotechnology may represent an alternative for the treatment of mycobacterial and fungal diseases.

Assessment of the nickel-albumin binding assay for diagnosis of acute coronary syndrome

Abstract Background: Myocardial ischemia may alter the metal binding capacity of circulating serum albumin. Thus, the aim of this study was to describe an automated method to measure ischemia-induced alterations in the binding capacity of serum albumin for exogenous nickel, and to evaluate the diagnostic characteristics of this assay for the assessment of acute coronary syndrome (ACS) in patients presenting to the emergency room (ER) with acute chest pain. Methods: We assessed the concentrations of cardiac troponin I (cTnI), serum albumin, ischemia-modified albumin (IMA) measured by the cobalt-albumin binding assay (CABA), and by an automated nickel-albumin binding assay (NABA) in the following groups: ACS (n=63) and non-ischemic chest pain (NICP, n=26). Biochemical markers were determined in blood samples obtained from patients within 3 h of ER admission. Results: cTnI, CABA and NABA concentrations were higher in ACS group in comparison to the NICP group. A significant correlation between NABA and CABA was observed (r=0.5387, p<0.001). Areas under the curve for CABA and NABA were 0.7289 and 0.7582, respectively. Both CABA and NABA have the ability to discriminate patients with ACS. However, NABA has a slightly higher ability to discriminate ACS compared with CABA. Conclusions: Patients with ACS have reduced nickel binding to human serum albumin, and NABA may have an important role as an early marker of myocardial ischemia, particularly in patients presenting to the ER with acute chest pain.

Characterization of three main degradation products from novel oral anticoagulant rivaroxaban under stress conditions by UPLC-Q-TOF-MS/MS

Drugs of long-term use may cause the accumulation of chemical compounds in human body. Therefore, the evaluation and structure characterization of synthesis and degradation impurities is substantial to guarantee drug safety and successful pharmaceutical therapy. The present work evaluated the anticoagulant rivaroxabana (RIV) under stress conditions in order to elucidate the chemical structure of major degradation products (DPs) formed after drug exposition to acid and alkaline hydrolysis, and UVC radiation. Analyses were performed in UPLC coupled to quadrupole time-of-flight MS. ESI was applied in positive mode, and C18 Agilent(®) column (2.1×50 mm, 1.8 μm) used for separation of compounds. RIV molecular íon [M+H](+) (m/z 436.07) was fragmented under 20 kV, best energetic condition to obtain clear and reproducible fragmentation pattern, assisting identification of RIV DPs. With support from UPLC separation and specific detection by MS/MS, three main degradation products (DP-1, DP-2, and DP-3) formed under stress conditions were successfully characterized. Presented study agrees with requirements for analytical assessment of impurities in pharmaceutical formulations, ensuring quality of pharmaceutical substances.

Anti biofilm effect of dihydromyricetin-loaded nanocapsules on urinary catheter infected by Pseudomonas aeruginosa

Nosocomial infections associated with biofilm formation on urinary catheters are among the leading causes of complications due to biofilm characteristics and high antimicrobial resistance. An interesting alternative are natural products, such as Dihydromyricetin (DMY), a flavonoid which presents several pharmacological properties, including strong antimicrobial activity against various microorganisms. However, DMY, has low aqueous solubility and consequently low bioavailability. Nanoencapsulation can contribute to the improvement of characteristics of some drugs, by increasing the apparent solubility and sustained release has been reported among other advantages. The aim of this study was to evaluate, for the first time, the feasibility of DMY nanoencapsulation, and to look at its influence on nanoencapsulation of DMY as well as verify its influence on antimicrobial and antibiofilm activity on urinary catheters infected by Pseudomonas aeruginosa. The physicochemical characterization showed an average diameter less than 170nm, low polydispersity index, positive zeta potential (between +11 and +14mV), slightly acidic pH. The values of the stability study results showed that the best condition for suspension storage without losing physical and chemical characteristics was under refrigeration (4±2°C). The antibiofilm activity of the formulations resulted in the eradication of biofilms both in free DMY formulations and in nanocapsules of DMY during those periods. However, within 96h the results of the inhibition of biofilm by DMY nanocapsules were more effective compared with free DMY. Thus, the nanocapsule formulation containing DMY can potentially be used as an innovative approach to urinary catheter biofilm treatment or prevention.

In Vitro Oxidation of Collagen Promotes the Formation of Advanced Oxidation Protein Products and the Activation of Human Neutrophils

The accumulation of advanced oxidation protein products (AOPPs) has been linked to several pathological conditions. Here, we investigated collagen as a potential source for AOPP formation and determined the effects of hypochlorous acid (HOCl)-treated collagen (collagen-AOPPs) on human neutrophil activity. We also assessed whether alpha-tocopherol could counteract these effects. Exposure to HOCl increased the levels of collagen-AOPPs. Collagen-AOPPs also stimulated the production of AOPPs, nitric oxide (NO), superoxide radicals (O2−), and HOCl by neutrophils. Collagen-AOPPs induced apoptosis and decreased the number of viable cells. Alpha-tocopherol prevented the formation of collagen-AOPPs, strongly inhibited the collagen-AOPP-induced production of O2− and HOCl, and increased the viability of neutrophils. Our results suggest that collagen is an important protein that interacts with HOCl to form AOPPs, and consequently, collagen-AOPP formation is related to human neutrophil activation and cell death.