Acetyl radical production by the methylglyoxal-peroxynitrite system: a possible route for L-lysine acetylation.

Methylglyoxal is an α-oxoaldehyde putatively produced in excess from triose phosphates, aminoacetone, and acetone in some disorders, particularly in diabetes. Here, we investigate the nucleophilic addition of ONOO(-), known as a potent oxidant and nucleophile, to methylglyoxal, yielding an acetyl radical intermediate and ultimately formate and acetate ions. The rate of ONOO(-) decay in the presence of methylglyoxal [k(2,app) = (1.0 ± 0.1) × 10(3) M(-1) s(-1); k(2) ≈ 1.0 × 10(5) M(-1) s(-1)] at pH 7.2 and 25 °C was found to be faster than that reported with monocarbonyl substrates (k(2) < 10(3) M(-1) s(-1)), diacetyl (k(2) = 1.0 × 10(4) M(-1) s(-1)), or CO(2) (k(2) = 3-6 × 10(4) M(-1) s(-1)). The pH profile of the methylglyoxal-peroxynitrite reaction describes an ascendant curve with an inflection around pH 7.2, which roughly coincides with the pK(a) values of both ONOOH and H(2)PO(4)(-) ion. Electron paramagnetic resonance spin trapping experiments with 2-methyl-2-nitrosopropane revealed concentration-dependent formation of an adduct that can be attributed to 2-methyl-2-nitrosopropane-CH(3)CO(•) (a(N) = 0.83 mT). Spin trapping with 3,5-dibromo-4-nitrosobenzene sulfonate gave a signal that could be assigned to a methyl radical adduct [a(N) = 1.41 mT; a(H) = 1.35 mT; a(H(m)) = 0.08 mT]. The 2-methyl-2-nitrosopropane-CH(3)CO(•) adduct could also be observed by replacement of ONOO(-) with H(2)O(2), although at much lower yields. Acetyl radicals could be also trapped by added L-lysine as indicated by the presence of (ε)N-acetyl-L-lysine in the spent reaction mixture. This raises the hypothesis that ONOO(-)/H(2)O(2) in the presence of methylglyoxal is endowed with the potential to acetylate proteins in post-translational processes.

Increased chemical acetylation of peptides and proteins in rats after daily ingestion of diacetyl analyzed by Nano-LC-MS/MS.

BACKGROUND: Acetylation alters several protein properties including molecular weight, stability, enzymatic activity, protein-protein interactions, and other biological functions. Our previous findings demonstrating that diacetyl/peroxynitrite can acetylate L-lysine, L-histidine, and albumin in vitro led us to investigate whether diacetyl-treated rats suffer protein acetylation as well. METHODS: Wistar rats were administered diacetyl daily for four weeks, after which they were sacrificed, and their lung proteins were extracted to be analysed by Nano-LC-MS/MS (Q-TOF). A C18 reversed-phase column and gradient elution with formic acid/acetonitrile solutions from 2 to 50% over 150 min were used to separate the proteins. Protein detection was performed using a microTOF-Q II (QTOF) equipped with captive source and an electrospray-ionization source. The data from mass spectrometry were processed using a Compass 1.7 and analyzed using Protein Scape, software that uses Mascot algorithms to perform protein searches. RESULTS: A set of 3,162 acetylated peptides derived from 351 acetylated proteins in the diacetyl-treated group was identified. Among them, 23 targeted proteins were significantly more acetylated in the diacetyl-treated group than in the PBS control. Protein acetylation of the group treated with 540 mg/kg/day of diacetyl was corroborated by Western blotting analysis. CONCLUSIONS: These data support our hypothesis that diacetyl exposure in animals may lead to the generation of acetyl radicals, compounds that attach to proteins, affecting their functions and triggering adverse health problems.

Effects of Diacetyl Flavoring Exposure in Mice Metabolism.

Diacetyl is a flavoring that imparts a buttery flavor to foods, but the use or exposure to diacetyl has been related to some diseases. We investigated the effect of oral intake of diacetyl in male and female C57/Bl mice. We performed a target metabolomics assay using ultraperformance liquid chromatography paired with triple quadrupole mass spectrometry (UPLC-MS/MS) for the determination and quantification of plasmatic metabolites. We observed alterations in metabolites present in the urea and tricarboxylic acid (TCA) cycles. Peroxynitrite plasmatic levels were evaluated by a colorimetric method, final activity of superoxide dismutase (SOD) was evaluated by an enzymatic method, and mouse behavior was evaluated. Majority of the assay showed differences between control and treatment groups, as well as between genders. This may indicate the involvement of sex hormones in the regulation of a normal metabolic profile, and the implication of sex differences in metabolite disease response.

Can in vivo surface dental enamelmicrobiopsies be used to measure remote lead exposure?

Measuring lead in the surface dental enamel (SDE) using biopsies is a rapid, safe, and painless procedure. The dental enamel lead levels (DELLs) decrease from the outermost superficial layer to the inner layer of dental enamel, which becomes crucial for the biopsy depth (BD) measurement. However, whether the origin of lead found in SDE is fully endogenous is not yet established. There is also controversy about the biopsy protocol. The aims of this study were to investigate if DELLs are altered by extrinsic contamination (A) and to evaluate the real geometric figure formed by the erosion provoked by biopsy procedure and the respective BD in SDE (B). To accomplish the aim A, lead from 90 bovine incisor crowns lead was determined by graphite furnace atomic absorption spectrometer as a function of exposure time and lead concentration. Two biopsies were performed in each tooth, before and after lead exposure. Six 15-tooth groups differed by exposure time (1 or 30 min) and lead concentrations (A. 0 mg/L-placebo, B. 0.01 mg/L-standard for drinking water, or C. 0.06 mg/L-concentration found in contaminated groundwater). Phosphorus was determined by an inductively coupled plasm optical emission spectrometer to quantify the enamel removed. To compare intakes/losses of lead in SDE among the groups, values of DELL differences between before and after lead exposure were compared by ANOVA (p < 0.05). To attain the objective B, one extracted human permanent tooth was studied by confocal Raman microscopy. Lead measurements and the surface profile were determined. There was no difference in DELL among the groups (p = 0.964). The biopsy bottom surface area, analyzed by microscopy, showed an irregular area, with regions of peaks and valleys, where areas with depth ranging from 0.2 (peaks) to 1.8 µm (valleys) (± 0.1 µm) could be found. BD carried out in vivo is commonly calculated using the cylinder height formula. The real BD was shown to be very similar to already published data. In conclusion, the SDE of erupted teeth does not seem to be susceptible to environmental lead intake, being thus reliable to measure remote exposures to lead.

What are the blood lead levels of children living in Latin America and the Caribbean?

INTRODUCTION: Information on the prevalence of lead exposure is essential to formulate efficient public health policies. Developed countries have implemented successful public policies for the prevention and control of lead poisoning. In the United States, Canada, Japan and the European Union, for instance, periodically repeated prevalence studies show that blood lead levels (BLLs) in children have decreased overall. Although BLL of Latino children in the U.S. have also dropped in recent years, the geometric mean remains higher than that of white children. Little is known about lead exposure in children in Latin America and the Caribbean (LAC). In this review, we responded to two questions: What is currently known about lead sources and levels in children in LAC? Are there public policies to prevent children's exposure to lead in LAC? METHOD: We conducted a literature review covering the period from January 2000 to March 2014 in the PubMed and Lilacs databases to obtain English, Portuguese and Spanish language studies reporting the prevalence of BLLs in children aged 0-18years living in LAC countries. No specific analytical method was selected, and given the scarcity of data, the study was highly inclusive. RESULTS: Fifty-six papers were selected from 16 different LAC countries. The children's BLLs found in this review are high (≥10µg/dL) compared to BLLs for the same age group in the U. S. However, most studies reported an association with some type of "lead hot spot", in which children can be exposed to lead levels similar to those of occupational settings. Only Peru and Mexico reported BLLs in children from population-based studies. CONCLUSIONS: Most BLLs prevalence studies carried out in LAC were in areas with known emission sources. The percentage of children at risk of lead poisoning in LAC is unknown, and probably underestimated. Thus, there is an urgent need to establish public health policies to quantify and prevent lead poisoning, specifically by prioritizing the identification and control of "hot spots".

Profiles of amino acids and biogenic amines in the plasma of Cri-du-Chat patients.

Cri-du-chat syndrome (CDCS) is a rare innate disease attributed to chromosome 5p deletion characterized by a cat-like cry, craniofacial malformation, and altered behavior of affected children. Metabolomic analysis and a chemometric approach allow description of the metabolic profile of CDCS as compared to normal subjects. In the present work, UHPLC/MS was employed to analyze blood samples withdrawn from CDCS carriers (n=18) and normal parental subjects (n=18), all aged 0-34 years, aiming to set up a representative CDCS profile constructed from 33 targeted amino acids and biogenic amines. Methionine sulfoxide (MetO) was of particular concern with respect to CDCS redox balance. Increased serotonin (3-fold), methionine sulfoxide (2-fold), and Asp levels, and a little lower Orn, citrulline, Leu, Val, Ile, Asn, Gln, Trp, Thr, His, Phe, Met, and creatinine levels were found in the plasma of CDCS patients. Nitrotyrosine and Trp did not differ in normal and CDCS individuals.The accumulated metabolites may reflect, respectively, disturbances in the redox balance, deficient purine biosynthesis, and altered behavior, whereas the amino acid abatement in the latter group may affect the homeostasis of the urea cycle, citric acid cycle, branched chain amino acid synthesis, Tyr and Trp metabolism and amino acid biosynthesis. The identification of enzymatic deficiencies leading to the amino acid burden in CDCS is further required for elucidating its molecular bases and eventually propose specific or mixed amino acid supplementation to newborn patients aiming to balance their metabolism.

Optimization and therapeutic effects of PDT mediated by ALA and MAL in the treatment of cutaneous malignant lesions: A comparative study.

5-aminolevulinic acid (ALA) and its methylated ester (MAL) are the most common topical agents used in photodynamic therapy (PDT) as precursors of the photosensitizer protoporphyrin IX (PpIX). The induction of newly PpIX depends on incubation time of each photosensitizer in the tissue and the presence of high intralesional porphyrin levels is an important parameter for the PDT effectiveness. This study used laser-induced fluorescence (LIF) spectroscopy to evaluate the optimum time to light exposure of PDT mediated by ALA (20% w/w) and MAL (10% w/w) to treat malignant lesions precursors of cutaneous squamous cell carcinoma induced in mice. The therapeutic effects obtained by optimized ALA- and MAL-PDT were assessed 10 and 20 days after treatments. Higher PpIX levels were evidenced in the lesions photosensitized by ALA than MAL and according to LIF measurements the PDT irradiation was performed, respectively, at 300 and 330 minutes after ALA and MAL incubation. Histopathological analysis evidenced necrosis and epithelial atrophy after 10 days of PDT using both prodrugs, as well as reepitelization and collagen deposition at 20 days. Thus, despite the distinct concentration of ALA and MAL used in the formulation of each photosensitizing cream, PDT mediated by both photosensitizing agents obtained similar therapeutic outcomes.

Luminescent threat: toxicity of light stick attractors used in pelagic fishery.

Light sticks (LS) are sources of chemiluminescence commonly used in pelagic fishery, where hundreds are discarded and reach the shores. Residents from fishing villages report an improper use of LS contents on the skin. Given the scarce information regarding LS toxicity, the effects of LS solutions in cell cultures were evaluated herein. Loss of viability, cell cycle changes and DNA fragmentation were observed in HepG2 cell line and skin fibroblasts. A non-cytotoxic LS concentration increased the occurrence of the mutagenic lesion 1,N(6)-εdAdo in HepG2 DNA by three-fold. Additionally, in vitro incubations of spent LS contents with DNA generated dGuo-LS adducts, whose structure elucidation revealed the presence of a reactive chlorinated product. In conclusion, the LS contents were found to be highly cyto- and genotoxic. Our data indicate an urgent need for LS waste management guidelines and for adequate information regarding toxic outcomes that may arise from human exposure.

Cocos nucifera Linn. (Palmae) husk fiber ethanolic extract: antioxidant capacity and electrochemical investigation.

The present study aims to determine the antioxidant capacity of the ethanolic extracts of husk fiber of four coconut (Cocos nucifera L.) varieties (yellow dwarf, green dwarf, giant and hybrid) and to evaluate the electrochemical behavior of these extracts on a glassy carbon electrode and on a modified glassy carbon electrode. The highest values of total phenolic content were obtained for the hybrid (531 ± 24 mg GAE g(-1) dry extract) and yellow dwarf (501 ± 29 mg GAE g(-1) dry extract) varieties and the lowest was for the green dwarf variety with 58 ± 9 mg GAE g(-1) dry extract. The ability of the extracts to scavenge DPPH˙ radicals was in the order of giant > yellow dwarf > hybrid > green dwarf and the IC50 values varied from 8.6 to 55.9 µg mL(-1). All varieties showed reducing potential by the use of FRAP and CUPRAC methods, with the lowest performance obtained for the green dwarf variety. Additionally, through the use of mimetic biomembranes, ethanolic extracts of coconut husk were shown to protect lipids against oxidative damage independent of the variety. The main antioxidants identified in the extract of yellow dwarf variety by UPLC-MS were quercetin and catechin. Cyclic voltammetric studies of the ethanolic extracts on glassy carbon electrode confirmed the presence of easily oxidized compounds, and the high antioxidant capacity of the varieties. This capacity was expressed as mg quercetin equivalents g(-1) dry extract and ranged from 25.9 up to 53.5 mg QE g(-1). A poly-xanthurenic acid (poly-Xa)/multi-walled carbon nanotube (MWCNT) / glassy carbon modified electrode (poly-Xa/MWCNT/GCE) was used for this purpose. Our findings suggest that these extracts are potentially important antioxidant supplements for the everyday human diet, pharmaceutical and cosmetic industries, thereby aggregating value to the enormous amount of waste from the coconut industry, mostly used for burning purposes.

Association of dental enamel lead levels with risk factors for environmental exposure.

OBJECTIVE: To analyze household risk factors associated with high lead levels in surface dental enamel. METHODS: A cross-sectional study was conducted with 160 Brazilian adolescents aged 1418 years living in poor neighborhoods in the city of Bauru, southeastern Brazil, from August to December 2008. Body lead concentrations were assessed in surface dental enamel acid-etch microbiopsies. Dental enamel lead levels were measured by graphite furnace atomic absorption spectrometry and phosphorus levels were measured by inductively coupled plasma optical emission spectrometry. The parents answered a questionnaire about their children's potential early (05 years old) exposure to well-known lead sources. Logistic regression was used to identify associations between dental enamel lead levels and each environmental risk factor studied. Social and familial covariables were included in the models. RESULTS: The results suggest that the adolescents studied were exposed to lead sources during their first years of life. Risk factors associated with high dental enamel lead levels were living in or close to a contaminated area (OR = 4.49; 95% CI: 1.69;11.97); and member of the household worked in the manufacturing of paints, paint pigments, ceramics or batteries (OR = 3.43; 95% CI: 1.31;9.00). Home-based use of lead-glazed ceramics, low-quality pirated toys, anticorrosive paint on gates and/or sale of used car batteries (OR = 1.31; 95% CI: 0.56;3.03) and smoking (OR = 1.66; 95% CI: 0.52;5.28) were not found to be associated with high dental enamel lead levels. CONCLUSIONS: Surface dental enamel can be used as a marker of past environmental exposure to lead and lead concentrations detected are associated to well-known sources of lead contamination.

Neurotoxicity and aggressiveness triggered by low-level lead in children: a review.

Lead-induced neurotoxicity acquired by low-level long-term exposure has special relevance for children. A plethora of recent reports has demonstrated a direct link between low-level lead exposure and deficits in the neurobehavioral-cognitive performance manifested from childhood through adolescence. In many studies, aggressiveness and delinquency have also been suggested as symptoms of lead poisoning. Several environmental, occupational and domestic sources of contaminant lead and consequent health risks are largely identified and understood, but the occurrences of lead poisoning remain numerous. There is an urgent need for public health policies to prevent lead poisoning so as to reduce individual and societal damages and losses. In this paper we describe unsuspected sources of contaminant lead, discuss the economic losses and urban violence possibly associated with lead contamination and review the molecular basis of lead-induced neurotoxicity, emphasizing its effects on the social behavior, delinquency and IQ of children and adolescents.

Association of dental enamel lead levels with risk factors for environmental exposure / Associação de níveis de chumbo no esmalte dentário com fatores de risco para exposição ambiental / Asociación de niveles de plomo en el esmalte dental con factores de riesgo a la exposición ambiental

OBJECTIVE: To analyze household risk factors associated with high lead levels in surface dental enamel. METHODS: A cross-sectional study was conducted with 160 Brazilian adolescents aged 1418 years living in poor neighborhoods in the city of Bauru, southeastern Brazil, from August to December 2008. Body lead concentrations were assessed in surface dental enamel acid-etch microbiopsies. Dental enamel lead levels were measured by graphite furnace atomic absorption spectrometry and phosphorus levels were measured by inductively coupled plasma optical emission spectrometry. The parents answered a questionnaire about their children's potential early (05 years old) exposure to well-known lead sources. Logistic regression was used to identify associations between dental enamel lead levels and each environmental risk factor studied. Social and familial covariables were included in the models. RESULTS: The results suggest that the adolescents studied were exposed to lead sources during their first years of life. Risk factors associated with high dental enamel lead levels were living in or close to a contaminated area (OR = 4.49; 95 percent CI: 1.69;11.97); and member of the household worked in the manufacturing of paints, paint pigments, ceramics or batteries (OR = 3.43; 95 percent CI: 1.31;9.00). Home-based use of lead-glazed ceramics, low-quality pirated toys, anticorrosive paint on gates and/or sale of used car batteries (OR = 1.31; 95 percent CI: 0.56;3.03) and smoking (OR = 1.66; 95 percent CI: 0.52;5.28) were not found to be associated with high dental enamel lead levels. CONCLUSIONS: Surface dental enamel can be used as a marker of past environmental exposure to lead and lead concentrations detected are associated to well-known sources of lead contamination.

OBJETIVO: Analisar fatores de risco no ambiente domiciliar associados com altos níveis de chumbo no esmalte dentário superficial. MÉTODOS: Estudo transversal conduzido com 160 adolescentes brasileiros (14 a 18 anos), residentes em bairros pobres do município de Bauru, SP, de agosto a dezembro de 2008. A concentração de chumbo no esmalte dentário foi avaliada por microbiópsias ácidas do esmalte dentário superficial, quantificada por espectrometria de absorção atômica com forno de grafite e a concentração de fósforo foi medida por espectrometria de absorção óptica com plasma indutivamente acoplado. Os pais dos adolescentes responderam a questionário sobre possível exposição prévia (cinco primeiros anos de vida do adolescente) a chumbo decorrente de fontes de contaminação bem conhecidas. Usou-se regressão logística para identificar associações entre concentração de chumbo no esmalte e fatores de risco ambientais. Covariáveis familiares e sociais foram incluídas nos modelos. RESULTADOS: Os resultados sugerem que os jovens avaliados foram expostos a fontes de chumbo durante seus primeiros anos de vida. Os fatores de risco associados com o desfecho foram residir em área contaminada por chumbo ou nas suas proximidades (OR = 4,49; IC 95 por cento: 1,69;11,97) e ter convivido, no mesmo domicílio, com pessoa que trabalhava em fábrica de tintas, pigmentos, cerâmicas ou baterias (OR = 3,43; IC 95 por cento: 1,31;9,00). Ter usado, em casa, cerâmica vitrificada, brinquedos de baixa qualidade ou piratas, ter aplicado zarcão em portões de ferro sem cobertura esmaltada ou armazenar baterias de carro usadas na residência (OR = 1,31; IC 95 por cento: 0,56;3,03) e hábito de fumar não foram associados com altas concentrações de chumbo no esmalte dentário (OR = 1,66; IC 95 por cento: 0,52;5,28). CONCLUSÕES: O esmalte dentário superficial pode ser utilizado como marcador de exposição ambiental passada ao chumbo e as concentrações encontradas desse metal estão ligadas a fontes bem conhecidas de contaminação por chumbo.

OBJETIVO: Analizar factores de riesgo en el ambiente domiciliar asociados con altos niveles de plomo en el esmalte dental superficial. MÉTODOS: Se realizó estudio transversal con 160 adolescentes brasileros (14 a 18 años), residentes en urbanizaciones pobres del municipio de Bauru, SP, de agosto a diciembre de 2008. La concentración de plomo en el esmalte dental fue evaluada por micro biopsias ácidas del esmalte dental superficial, cuantificada por espectrometría de absorción atómica con horno de grafito y la concentración de fósforo fue medida por espectrometría de absorción óptica con plasma inductivamente acoplado. Los padres de los adolescentes respondieron a cuestionario sobre posible exposición previa (5 primeros años de vida del adolescente) al plomo producto de fuentes de contaminación bien conocidas. Se usó regresión logística para identificar asociaciones entre concentración de plomo en el esmalte y factores de riesgo ambientales. Covariables familiares y sociales fueron incluidas en los modelos. RESULTADOS: Los resultados sugieren que los jóvenes evaluados fueron expuestos a fuentes de plomo durante sus primeros años de vida. Los factores de riesgo asociados con el resultado fueron residir en área contaminada por plomo o en sus proximidades (OR=4,49; IC 95 por ciento: 1,69;11,97) y haber convivido, en el mismo domicilio, con persona que trabajaba en fábrica de tintas, pigmentos, cerámicas o baterías (OR= 3,43; IC 95 por ciento: 1,31;9,00). Haber usado, en casa, cerámica vitrificada, juegos de baja calidad o piratas, haber aplicado zircón en portones de hierro sin cobertura esmaltada o almacenar baterías de carro usadas en la residencia (OR= 1,31; IC 95 por ciento: 0,56-3,03) y hábito de fumar no fueron asociados con altas concentraciones de plomo en el esmalte dental (OR=1,66; IC 95 por ciento: 0,52;5,28). CONCLUSIONES: El esmalte dental superficial puede ser utilizado como marcador de exposición ambiental pasada al plomo y las concentraciones encontradas de dicho metal están relacionadas con fuentes bien conocidas de contaminación por plomo.

Neurotoxicity and aggressiveness triggered by low-level lead in children: a review / Neurotoxicidad y agresividad desencadenadas por bajos niveles de plomo en niños: una revisión

Lead-induced neurotoxicity acquired by low-level long-term exposure has special relevance for children. A plethora of recent reports has demonstrated a direct link between low-level lead exposure and deficits in the neurobehavioral-cognitive performance manifested from childhood through adolescence. In many studies, aggressiveness and delinquency have also been suggested as symptoms of lead poisoning. Several environmental, occupational and domestic sources of contaminant lead and consequent health risks are largely identified and understood, but the occurrences of lead poisoning remain numerous. There is an urgent need for public health policies to prevent lead poisoning so as to reduce individual and societal damages and losses. In this paper we describe unsuspected sources of contaminant lead, discuss the economic losses and urban violence possibly associated with lead contamination and review the molecular basis of lead-induced neurotoxicity, emphasizing its effects on the social behavior, delinquency and IQ of children and adolescents.

La neurotoxicidad adquirida inducida por la exposición prolongada a bajos niveles de plomo tiene una importancia especial en los niños. Una plétora de publicaciones recientes ha demostrado el vínculo directo existente entre la exposición a bajos niveles de plomo y el déficit en el desempeño neuroconductual-cognitivo manifestado desde la infancia hasta el final de la adolescencia. En numerosos estudios, la agresividad y la delincuencia juvenil también se han considerado síntomas de la intoxicación por plomo. Se han identificado y explicado ampliamente varias fuentes ambientales, laborales y domésticas de contaminación por plomo y los riesgos resultantes para la salud, pero aún son numerosos los casos de intoxicación por plomo. Se necesitan urgentes políticas de salud pública para prevenir la intoxicación por plomo de manera de reducir los daños y las pérdidas, tanto individuales como para la sociedad. En este artículo se describen algunas fuentes no sospechadas de contaminación por plomo y se discuten las pérdidas económicas y la violencia urbana posiblemente asociada con este tipo de contaminación. Además, se hace una revisión de las bases moleculares de la neurotoxicidad inducida por plomo, con énfasis en sus efectos sobre el comportamiento social, la delincuencia juvenil y el coeficiente intelectual de los niños y los adolescentes.