Mônica Siqueira Ferreira

Mass spectrometry imaging: an expeditious and powerful technique for fast in situ lignin assessment in Eucalyptus.

Plant biomass has been suggested as an alternative to produce bioethanol. The recalcitrance of plant biomass to convert cellulose into simpler carbohydrates used in the fermentation process is partially due to lignin, but the standard methods used to analyze lignin composition frequently use toxic solvents and are laborious and time-consuming. MS imaging was used to study lignin in Eucalyptus, since this genus is the main source of cellulose in the world. Hand-cut sections of stems of two Eucalyptus species were covered with silica and directly analyzed by matrix-assisted laser sesorption ionization (MALDI)-imaging mass spectrometry (MS). Information available in the literature about soluble lignin subunits and structures were used to trace their distribution in the sections and using a software image a relative quantification could be made. Matrixes routinely used in MALDI-imaging analysis are not satisfactory to analyze plant material and were efficiently substituted by thin layer chromatography (TLC) grade silica. A total of 22 compounds were detected and relatively quantified. It was also possible to establish a proportion between syringyl and guaiacyl monolignols, characteristic for each species. Because of the simple way that samples are prepared, the MALDI-imaging approach presented here can replace, in routine analysis, complex and laborious MS methods in the study of lignin composition.

Non-effect of p22-phox -930A/G polymorphism on end-organ damage in Brazilian hypertensive patients.

The p22-phox subunit is an essential component of NAD(P)H oxidase enzymatic complex, which is considered the major source of oxidative stress products in the cardiovascular system. The -930G allele of p22-phox has been associated with higher promoter activity, increased NAD(P)H oxidase-mediated oxidative stress and hypertension. We recently reported that left ventricular hypertrophy is accompanied by increased myocardial p22-phox expression in aortic-banded rats, suggesting that this protein might be involved in hypertensive cardiac hypertrophy.

Cosmetic Analysis Using Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry Imaging (MALDI-MSI)

A new “omic” platform—Cosmetomics—that proves to be extremely simple and effective in terms of sample preparation and readiness for data acquisition/interpretation is presented. This novel approach employing Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry Imaging (MALDI-MSI) for cosmetic analysis has proven to readily identify and quantify compounds of interest. It also allows full control of all the production phases, as well as of the final product, by integration of both analytical and statistical data. This work has focused on products of daily use, namely nail polish, lipsticks and eyeliners of multiple brands sold in the worldwide market.

S-nitrosoglutathione inhibits inducible nitric oxide synthase upregulation by redox posttranslational modification in experimental diabetic retinopathy.

PURPOSE Diabetic retinopathy (DR) is associated with nitrosative stress. The purpose of this study was to evaluate the beneficial effects of S-nitrosoglutathione (GSNO) eye drop treatment on an experimental model of DR. METHODS Diabetes (DM) was induced in spontaneously hypertensive rats (SHR). Treated animals received GSNO eye drop (900 nM or 10 μM) twice daily in both eyes for 20 days. The mechanisms of GSNO effects were evaluated in human RPE cell line (ARPE-19). RESULTS In animals with DM, GSNO decreased inducible nitric oxide synthase (iNOS) expression and prevented tyrosine nitration formation, ameliorating glial dysfunction measured with glial fibrillary acidic protein, resulting in improved retinal function. In contrast, in nondiabetic animals, GSNO induced oxidative/nitrosative stress in tissue resulting in impaired retinal function. Nitrosative stress was present markedly in the RPE layer accompanied by c-wave dysfunction. In vitro study showed that treatment with GSNO under high glucose condition counteracted nitrosative stress due to iNOS downregulation by S-glutathionylation, and not by prevention of decreased GSNO and reduced glutathione levels. This posttranslational modification probably was promoted by the release of oxidized glutathione through GSNO denitrosylation via GSNO-R. In contrast, in the normal glucose condition, GSNO treatment promoted nitrosative stress by NO formation. CONCLUSIONS In this study, a new therapeutic modality (GSNO eye drop) targeting nitrosative stress by redox posttranslational modification of iNOS was efficient against early damage in the retina due to experimental DR. The present work showed the potential clinical implications of balancing the S-nitrosoglutathione/glutathione system in treating DR.

Lipid characterization of embryo zones by silica plate laser desorption ionization mass spectrometry imaging (SP-LDI-MSI)

Lipid pathways play important biological roles in mammalian embryology, directing early developmental pathways to differentiation. Phospholipids and triglycerides, among others, are the main composing lipids of zona pellucida in several embryo species. Lipid analysis in embryos by mass spectrometry usually requires sample preparation and/or matrix application. This novel approach using silica plate laser desorption/ionization mass spectrometry imaging (SP-LDI-MSI) allows direct single-cell imaging and embryo region discrimination with no matrix coating. Its application is herein described for two- and eight-cell embryos. Lipid biomarkers for blastomere and intact zona pellucida are reported and corroborated by both fragmentation reactions (MS/MS) and images. Results obtained in this work are understood to be of great use for further developments on in vitro bovine fertilization. Since much of the processes can be monitored by characteristic biomarkers, it is now possible to precisely identify cell division errors during early embryo stages, as well as evaluate pre-implantation conditions.

Reduced graphene oxide induces transient blood–brain barrier opening: an in vivo study

BackgroundThe blood–brain barrier (BBB) is a complex physical and functional barrier protecting the central nervous system from physical and chemical insults. Nevertheless, it also constitutes a barrier against therapeutics for treating neurological disorders. In this context, nanomaterial-based therapy provides a potential alternative for overcoming this problem. Graphene family has attracted significant interest in nanomedicine because their unique physicochemical properties make them amenable to applications in drug/gene delivery and neural interface.ResultsIn this study, reduced graphene oxide (rGO) systemically-injected was found mainly located in the thalamus and hippocampus of rats. The entry of rGO involved a transitory decrease in the BBB paracellular tightness, as demonstrated at anatomical (Evans blue dye infusion), subcellular (transmission electron microscopy) and molecular (junctional protein expression) levels. Additionally, we examined the usefulness of matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) as a new imaging method for detecting the temporal distribution of nanomaterials throughout the brain.ConclusionsrGO was able to be detected and monitored in the brain over time provided by a novel application for MALDI-MSI and could be a useful tool for treating a variety of brain disorders that are normally unresponsive to conventional treatment because of BBB impermeability.

Rapid and Simultaneous In Situ Assessment of Aflatoxins and Stilbenes Using Silica Plate Imprinting Mass Spectrometry Imaging

A fast and direct combination of techniques for simultaneous mycotoxin and phytoalexin identification in peanut skin and kernel is described. Silica Plate Imprinting Laser Desorption/Ionization Mass Spectrometry Imaging (SPILDI-MSI) is a powerful technique that exhibits great advantages, such as solvent-free and matrix-free characteristics, as well as no sample preparation or separation steps. It also permits accurate identification of mycotoxins and phytoalexins with unique fingerprint profiles in just a few seconds. Results are expressed as chemical images of the 4 identified types of aflatoxins (B1, B2, G1 and G2) and a stilbenoid (resveratrol). Also, SPILDI-MSI allows the comparison between the spatial distribution of aflatoxins and resveratrol found in kernel and skin. This novel application has proven to be useful for instantaneous qualitative assessment of aflatoxins and stilbenoids both in the peanut skin and kernel and offers precise tracking of fungal contamination in nuts and other foodstuffs.

In situ assessment of atorvastatin impurity using MALDI mass spectrometry imaging (MALDI-MSI)

The analysis of impurities and degradation products in pharmaceutical preparations are usually performed by chromatographic techniques such as high-performance liquid chromatography (HPLC). This approach demands extensive analysis time, mostly due to extraction and separation phases. These steps must be carried out in samples in order to adapt them to the requirements of the analytical method of choice. In the present contribution, matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) was employed to quantify an important degradation product in atorvastatin calcium 80 mg tablets: the atorvastatin lactone. Through the standard of the impurity, it was possible to perform quantitative analysis directly on the drug tablet, using a quick and novel approach, suitable for quality control processes in the pharmaceutical industry.

Revealing praziquantel molecular targets using mass spectrometry imaging: an expeditious approach applied to Schistosoma mansoni

Finding specific molecular targets and the mechanism of action of praziquantel in the treatment of schistosomiasis remains a challenging task. Our efforts were focused on obtaining further information on worm composition before and after exposure to praziquantel in the treatment of schistosomiasis to elucidate the potential sites of action of this drug. Evidence indicates that the lipid bilayer is changed by treatment with praziquantel. Following this rationale, we employed a mass spectrometry imaging-based approach that helped to characterise lipids in specific locations, which are directly involved in the biochemical pathways of the BH strain of Schistosoma mansoni, as well as differentiating the molecular response that each worm sex presents in vivo. Our findings demonstrated significant differences between the chemical markers found in adult worms before and after praziquantel exposure, especially in phospholipids, which were predominantly identified as chemical markers in all samples. Results also indicate that distinct molecular pathways in both male and female worms could be differentially affected by praziquantel treatment. These data shine new light on the mechanism of action of praziquantel, taking a further step towards its full understanding.

High-throughput analysis by SP-LDI-MS for fast identification of adulterations in commercial balsamic vinegars

Balsamic vinegar (BV) is a typical and valuable Italian product, worldwide appreciated thanks to its characteristic flavors and potential health benefits. Several studies have been conducted to assess physicochemical and microbial compositions of BV, as well as its beneficial properties. Due to highly-disseminated claims of antioxidant, antihypertensive and antiglycemic properties, BV is a known target for frauds and adulterations. For that matter, product authentication, certifying its origin (region or country) and thus the processing conditions, is becoming a growing concern. Striving for fraud reduction as well as quality and safety assurance, reliable analytical strategies to rapidly evaluate BV quality are very interesting, also from an economical point of view. This work employs silica plate laser desorption/ionization mass spectrometry (SP-LDI-MS) for fast chemical profiling of commercial BV samples with protected geographical indication (PGI) and identification of its adulterated samples with low-priced vinegars, namely apple, alcohol and red/white wines.