Fractionation of selenium isotopes during biofortification of Saccharomyces cerevisiae and the influence of metabolic labeling with 15N.

Isotope fractionation of metals/metalloids in biological systems is an emerging research area that demands the application of state-of-the-art analytical chemistry tools and provides data of relevance to life sciences. In this work, Se uptake and Se isotope fractionation were measured during the biofortification of baker's yeast (Saccharomyces cerevisiae)-a product widely used in dietary Se supplementation and in cancer prevention. On the other hand, metabolic labeling with 15N is a valuable tool in mass spectrometry-based comparative proteomics. For Se-yeast, such labeling would facilitate the assessment of Se impact on yeast proteome; however, the question arises whether the presence of 15N in the microorganisms affects Se uptake and its isotope fractionation. To address the above-mentioned aspects, extracellularly reduced and cell-incorporated Se fractions were analyzed by hydride generation-multi-collector inductively coupled plasma-mass spectrometry (HG MC ICP-MS). It was found that extracellularly reduced Se was enriched in light isotopes; for cell-incorporated Se, the change was even more pronounced, which provides new evidence of mass fractionation during biological selenite reduction. In the presence of 15N, a weaker preference for light isotopes was observed in both, extracellular and cell-incorporated Se. Furthermore, a significant increase in Se uptake for 15N compared to 14N biomass was found, with good agreement between hydride generation microwave plasma-atomic emission spectrometry (HG MP-AES) and quadrupole ICP-MS results. Biological effects observed for heavy nitrogen suggest 15N-driven alteration at the proteome level, which facilitated Se access to cells with decreased preference for light isotopes.

Antinociceptive and anti-inflammatory effects of Cuphea aequipetala Cav (Lythraceae).

Cuphea aequipetala Cav (Lythraceae) is an herb used in folk treatment for pain and inflammation. The aim of this study was to evaluate the antinociceptive and anti-inflammatory actions of an ethanol extract from the leaves and stem of Cuphea aequipetala (CAE). The antinociceptive actions of CAE (10-200 mg/kg p.o.) were assessed with the acetic acid-induced writhing, hot plate, and formalin tests. The possible mechanism of action of CAE was evaluated using inhibitors. The effects of CAE on motor coordination were assessed by the rotarod test. The in vitro anti-inflammatory actions of CAE were evaluated using LPS-stimulated primary murine macrophages, and the in vivo anti-inflammatory actions were assessed by the TPA-induced ear oedema and the carrageenan-induced paw oedema tests. The production of inflammatory mediators was estimated from both in vitro and in vivo assays. CAE showed antinociception (ED50 = 90 mg/kg) in the acetic acid test and in the second phase of the formalin test (ED50 = 158 mg/kg). Pretreatment with glibenclamide or L-NAME partially reversed the antinociception shown by the plant extract. CAE (50-200 mg/kg) did not affect motor coordination in mice. CAE increased the production of IL-10 in LPS-stimulated macrophages (EC50 = 10 pg/ml) and, in the carrageenan-induced paw oedema test (threefold increase). In conclusion, CAE induced antinociceptive effects without affecting motor coordination, probably due to the involvement of nitric oxide and ATP-sensitive K+ channels. CAE also exerts in vitro and in vivo anti-inflammatory effects by increasing the release of IL-10.

Magnesium-Isotope Fractionation in Chlorophyll-a Extracted from Two Plants with Different Pathways of Carbon Fixation (C3, C4).

Relatively few studies have been focused so far on magnesium-isotope fractionation during plant growth, element uptake from soil, root-to-leaves transport and during chlorophylls biosynthesis. In this work, maize and garden cress were hydroponically grown in identical conditions in order to examine if the carbon fixation pathway (C4, C3, respectively) might have impact on Mg-isotope fractionation in chlorophyll-a. The pigment was purified from plants extracts by preparative reversed phase chromatography, and its identity was confirmed by high-resolution mass spectrometry. The green parts of plants and chlorophyll-a fractions were acid-digested and submitted to ion chromatography coupled through desolvation system to multiple collector inductively coupled plasma-mass spectrometry. Clear preference for heavy Mg-isotopes was found in maize green parts (∆26Mgplant-nutrient 0.65, 0.74 for two biological replicates, respectively) and in chlorophyll-a (∆26Mgchlorophyll-plant 1.51, 2.19). In garden cress, heavy isotopes were depleted in green parts (∆26Mgplant-nutrient (-0.87)-(-0.92)) and the preference for heavy isotopes in chlorophyll-a was less marked relative to maize (∆26Mgchlorophyll-plant 0.55-0.52). The observed effect might be ascribed to overall higher production of energy in form of adenosine triphosphate (ATP), required for carbon fixation in C4 compared to C3, which could reduce kinetic barrier and make equilibrium fractionation prevailing during magnesium incorporation to protoporphyrin ring.

Determination of sulfonated azo dyes in chili powders by MALDI-TOF MS.

The application of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) is presented for the determination of five sulfonated azo dyes in chili powders. To circumvent problems related to spectral noise and overall poor precision, acid red 88 was used as internal standard and sample cleanup was performed via ion pairing of anionic species with benzyltributylammonium bromide (BTAB) and extraction into chloroform. The key parameters influencing analytical performance were BTAB concentration, pH of the aqueous phase, amount of sample and deposition technique, concentration of 9-aminoacridine (chemical matrix), number of instant spectra per laser shot, and the raster of laser movement. The highest sample load corresponded to 100 µL of water/methanol extract taken for extraction and the method quantification limits for sunset yellow (Y6), ponceau 2R (R5), allura red (R40), and amaranth (R2) were within the range 1.50-3.10 µg g-1 (29.0 µg g-1 for tartrazine, Y5). Two-point standard addition performed in three samples yielded percentage recoveries in the range 86.4-115%; the quantification results were consistent with those obtained by HPLC-DAD. Twelve chili powders were analyzed and the results for nine of them disagreed with information provided by the manufacturers; R40 was determined in seven products at concentrations from 32.5 ± 2.1 µg g-1 to 1125 ± 73 µg g-1; Y6 and Y5 were found at lower concentrations and in fewer samples. The MALDI-TOF MS procedure can be recommended for routine control of sulfonated azo dyes in food products as a memory-free, procedurally simple, high-throughput procedure with minimal costs of instrument operation. Outline of the proposed MALDI-TOF MS procedure.

LC-MS/MS proteomic analysis of starved Bacillus subtilis cells overexpressing ribonucleotide reductase (nrdEF): implications in stress-associated mutagenesis.

The non-appropriate conditions faced by nutritionally stressed bacteria propitiate error-prone repair events underlying stationary-phase- or stress-associated mutagenesis (SPM). The genetic and molecular mechanisms involved in SPM have been deeply studied but the biochemical aspects of this process have so far been less explored. Previous evidence showed that under conditions of nutritional stress, non-dividing cells of strain B. subtilis YB955 overexpressing ribonucleotide reductase (RNR) exhibited a strong propensity to generate true reversions in the hisC952 (amber), metB5 (ochre) and leuC425 (missense) mutant alleles. To further advance our knowledge on the metabolic conditions underlying this hypermutagenic phenotype, a high-throughput LC-MS/MS proteomic analysis was performed in non-dividing cells of an amino acid-starved strain, deficient for NrdR, the RNR repressor. Compared with the parental strain, the level of 57 proteins was found to increase and of 80 decreases in the NrdR-deficient strain. The proteomic analysis revealed an altered content in proteins associated with the stringent response, nucleotide metabolism, DNA repair, and cell signaling in amino acid-starved cells of the ∆nrdR strain. Overall, our results revealed that amino acid-starved cells of strain B. subtilis ∆nrdR that escape from growth-limiting conditions exhibit a complex proteomic pattern reminiscent of a disturbed metabolism. Future experiments aimed to understand the consequences of disrupting the cell signaling pathways unveiled in this study, will advance our knowledge on the genetic adaptations deployed by bacteria to escape from growth-limiting environments.

Determination of copper and lead in tequila by conventional matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and partial least squares regression.

RATIONALE: Quantification of small molecules by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) is challenging yet attractive, due to micro-scale procedural simplicity, high throughput and lack of memory effects. Since these features are important while analyzing trace elements in quality control schemes, MALDI-TOFMS was used for the determination of copper (Cu) and lead (Pb) in tequila with quantification carried out by partial least squares regression (PLS2) and by univariate calibration (UC). METHODS: In the proposed procedure, Bi(III) was added as internal standard (IS), diethyldithiocarbamate complexes were formed (pH 7.4) and extracted into chloroform; after solvent evaporation and re-constitution in acetonitrile, the sample was co-crystallized with α-cyano-4-hydroxycinnamic acid on a steel target. From the acquired mass spectra, UC was performed using IS-normalized signals of the monoisotopic ions of analytes, and the m/z range 350-513 was used for PLS2. Accuracy was tested by recovery experiments and by inductively coupled plasma (ICP)-MS analysis. RESULTS: When compared with direct analyte signal measurements, application of IS yielded enhanced analytical performance using either UC or PLS2; the method quantification limits were: 11.1 µg L-1 , 23.4 µg L-1 for Cu and 89.8 µg L-1 , 97.1 µg L-1 for Pb, respectively. In tequila, MALDI-TOFMS and ICP-MS provided consistent results for Cu (165-2599 µg L-1 ); Pb was not detected in any sample by MALDI-TOFMS, yet recoveries obtained after standard addition were indicative of acceptable accuracy (400 µg L-1 Pb added; recoveries: 91.2-108% for UC and 98.8-120% for PLS2). CONCLUSIONS: New experimental evidence has been provided supporting the inclusion of trace metals quantification within a range of MALDI-TOFMS applications. Slightly better results were obtained for UC as compared with PLS2 yet both methods can be recommended for testing the compliance of Cu and Pb levels with Official Mexican Norm. Of note, while using PLS2, there is no need for signal integration nor for IS normalization.

Gold(i)-catalysed high-yielding synthesis of indenes by direct Csp3-H bond activation.

A catalytic, practical and high-yielding procedure for the synthesis of indenes by direct Csp3-H activation under gold(i) catalysis was developed. The scope of the protocol was determined by synthesizing some electron-neutral, electron-poor as well as electron-rich derivatives including the dibenzofurane and carbazole heterocycles. The mechanism of this reaction was elucidated by theoretical calculations using a ONIOM(M08-HX/mixed-basis:PM6) hybrid scheme. Thereby we found a pericyclic transformation involving a [1,5]-H shift generating a gold(i)-carbene that evolves to the indene derivative. In comparison with several reports, our protocol presents a direct activation of the Csp3-H bond.

Effects of lead and lead-melatonin exposure on protein and gene expression of metal transporters, proteins and the copper/zinc ratio in rats.

Human lead (Pb) exposure induces many adverse health effects, including some related to lead accumulation in organs. Although lead bio-distribution in the body has been described, the molecular mechanism underlying distribution and excretion is not well understood. The transport of essential and toxic metals is principally mediated by proteins. How lead affects the expression of metal transporter proteins in the principal metal excretory organs, i.e., the liver and kidney, is unknown. Considering that co-administration of melatonin and lead reduces the toxic effects of lead and lead levels in the blood in vivo, we examined how lead and co-administration of lead and melatonin affect the gene and protein expression of metal transporter proteins (ZIP8, ZIP14, CTR1 and DMT1) in these organs. Rats were exposed intraperitoneally to lead or lead-melatonin. Our results show that Pb exposure induces changes in the protein and gene expression of ZIP8, ZIP14 and CTR1. Alterations in the copper/zinc ratio found in the blood, liver and kidney were likely related to these changes. With DMT1 expression (gene and protein), a positive correlation was found with lead levels in the kidney. Co-administration of melatonin and lead reduced lead-induced DMT1 expression through an unknown mechanism. This effect of melatonin relates to reduced lead levels in the blood and kidney. The metal transport protein function and our results suggest that DMT1 likely contributes to lead accumulation in organs. These data further elucidate the effects of lead on Cu and Zn and the molecular mechanism underlying lead bio-distribution in animals.

Advanced glycation end products and their receptors did not show any association with body mass parameters in metabolically healthy adolescents.

AIM: We determined the relationship between circulating advanced glycation end products (AGEs), AGE receptors and homeostatic model assessment for insulin resistance (HOMA-IR) in metabolically healthy obese and normal weight adolescents. METHODS: In 2015, we recruited 80 normal weight adolescents and 80 with obesity from schools Leon city, Mexico, and put them into metabolically healthy (HOMA-IR <3.0) and unhealthy (HOMA-IR >3.0) groups. We measured their body mass index (BMI) and carried out detailed blood analyses. RESULTS: We found a higher triglycerides, triglycerides/high-density lipoproteins cholesterol (TG/HDL-C) index, HOMA-IR, tumour necrosis factor alpha (TNF-α) and interleukin-6 (IL-6) in the metabolically healthy group and found correlations between HOMA-IR with BMI, the TG/HDL-C index and IL-6 and the TG/HDL-C index and BMI and (TNF-α). There was no correlation between markers of obesity and circulating N-carboxymethyl-lysine (CML) or soluble receptor for advanced glycation end products (sRAGE). Some unhealthy adolescents had higher CML (15.5 ± 2.7 U/mL, p < 0.028) and sRAGE (3123 ± 1364 pg/mL, p < 0.001) than the healthy group. CONCLUSION: HOMA-IR and the TG/HDL-C index were associated with BMI and inflammation markers. CML and sRAGE were not associated with obesity or inflammation. These parameters were higher in unhealthy obese adolescents.

Determination of fatty acid methyl esters in cosmetic castor oils by flow injection - electrospray ionization - high resolution mass spectrometry.

OBJECTIVE: The goal of this work was to set up a high throughput procedure for the determination of fatty acid methyl esters (FAMEs) in cosmetic castor oils using flow injection - electrospray ionization - high resolution mass spectrometry, and to demonstrate the need of such analysis for the quality control purposes. METHODS: The sample aliquot was mixed with isooctane:chloroform (1:1) and submitted to transesterification; the obtained FAMEs were appropriately diluted using water:isopropanol:acetonitrile (20:50:30) with addition of sodium formate which served as an internal standard, lock mass calibrant and promoted the formation of sodium adducts during electrospray ionization (ESI). The principle of flow injection analysis (FIA) was applied for sample introduction to an ESI - quadrupole- time of flight mass spectrometer (ESI-QTOFMS). The carrier solution was composed of water:isopropanol:acetonitrile (20:50:30). From the acquired MS data, flowgrams of the extracted [M+Na]+ ions were obtained using the following m/z values for individual FAMEs: 293.2451 (C16:0); 315.2295 (C18:3); 317.2451 (C18:2); 319.2608 (C18:1); 321.2764 (C18:0); 335.2557 (C18:1,OH); 349.3077 (C20:0); 377.3390 (C22:0) and m/z 226.9515 for IS. Baseline-subtracted and filtered signals were integrated and the list of peaks intensities was exported to Excel, where calibration functions were obtained and quantification carried out. Gas chromatography with a flame ionization detector (GC-FID) was used as an alternative analytical tool. RESULTS: The calibration detection limits for FAMEs of unsaturated fatty acids were in the range 3.61 - 8.62 µg L-1 and for saturated compounds in the range 8.51 - 82.4 µg L-1 . The results obtained for commercial were in good agreement with GC-FID data; among nine cosmetic oils analyzed, three contained low concentrations of ricinoleic acid (C18:1, OH), indicating adulteration of castor bean oil with other vegetable oils. CONCLUSION: Application of FIA for the sample introduction to ESI-QTOFMS enabled for reliable determination of FAMEs in cosmetic oils with sampling frequency of thirty per hour as compared to two samples per hour achievable using GC-FID. The proposed procedure is especially well suited for FAMEs of unsaturated fatty acids that are primary components of castor triacylglycerides, and contribute to desirable properties of any cosmetic oil. This article is protected by copyright. All rights reserved.

Application of liquid chromatography/electrospray ionization ion trap tandem mass spectrometry for the evaluation of global nucleic acids: methylation in garden cress under exposure to CuO nanoparticles.

RATIONALE: A full understanding of the biological impact of nanomaterials demands analytical procedures suitable for the detection/quantification of epigenetic changes that occur in the exposed organisms. Here, the effect of CuO nanoparticles (NPs) on global methylation of nucleic acids in Lepidium sativum was evaluated by liquid chromatography/ion trap mass spectrometry. Enhanced selectivity toward cytosine-containing nucleosides was achieved by using their proton-bound dimers formed in positive electrospray ionization (ESI(+)) as precursor ions for multiple reaction monitoring (MRM) quantification based on one or two ion transitions. METHODS: Plants were exposed to CuO NPs (0-1000 mg L(-1)); nucleic acid extracts were washed with bathocuproine disulfate; nucleosides were separated on a Luna C18 column coupled via ESI(+) to an AmaZon SL mass spectrometer (Bruker Daltonics). Cytidine, 2´-deoxycytidine, 5-methylcytidine, 5-methyl-2´-deoxycytidine and 5-hydroxymethyl-2´-deoxycytidine were quantified by MRM based on MS(3) ([2M+H](+)/[M+H](+)/[M+H-132](+) or [M+H-116](+)) and MS(2) ([2M+H](+)/[M+H](+) ). RESULTS: Bathocuproine disulfate, added as Cu(I) complexing agent, allowed for elimination of [2M+Cu](+) adducts from the mass spectra. Poorer instrumental detection limits were obtained for MS(3) (20-120 fmol) as compared to MS(2) (9.0-41 fmol); however, two ion transitions helped to eliminate matrix effects in plant extracts. The procedure was tested by analyzing salmon sperm DNA (Sigma) and applied for the evaluation of DNA and RNA methylation in plants; in the absence of NPs, 13.03% and 0.92% methylated cytosines were found in DNA and RNA, respectively; for NPs concentration >50 mg L(-1), DNA hypomethylation was observed with respect to unexposed plants. RNA methylation did not present significant changes upon plant exposure; 5-hydroxymethyl-2´-deoxycytidine was not detected in any sample. CONCLUSIONS: The MRM quantification proposed here of cytosine-containing nucleosides using their proton-bound homo-dimers as precursor ions proved its utility for the assessment of global methylation of DNA and RNA in plants under stress imposed by CuO NPs. Detection of copper adducts with cytosine-containing ions, and their elimination by washing extracts with Cu(I) chelator, calls for further investigation.

The trans fatty acid elaidate affects the global DNA methylation profile of cultured cells and in vivo.

BACKGROUND: The deleterious effects of dietary trans fatty acids (tFAs) on human health are well documented. Although significantly reduced or banned in various countries, tFAs may trigger long-term responses that would represent a valid human health concern, particularly if tFAs alter the epigenome. METHODS: Based on these considerations, we asked whether the tFA elaidic acid (EA; tC18:1) has any effects on global DNA methylation and the transcriptome in cultured human THP-1 monocytes, and whether the progeny of EA-supplemented dams during either pregnancy or lactation in mice (n = 20 per group) show any epigenetic change after exposure. RESULTS: EA induced a biphasic effect on global DNA methylation in THP-1 cells, i.e. hypermethylation in the 1-50 µM concentration range, followed by hypomethylation up to the 200 µM dose. On the other hand, the cis isomer oleic acid (OA), a fatty acid with documented beneficial effects on human health, exerted a distinct response, i.e. its effects were weaker and only partially overlapping with EA's. The maximal differential response between EA and OA was observed at the 50 µM dose. Array expression data revealed that EA induced a pro-inflammatory and adipogenic transcriptional profile compared with OA, although with modest effects on selected (n = 9) gene promoter methylation. In mice, maternal EA supplementation in utero or via the breastmilk induced global adipose tissue DNA hypermethylation in the progeny, that was detectable postnatally at the age of 3 months. CONCLUSION: We document that global DNA hypermethylation is a specific and consistent response to EA in cell culture and in mice, and that EA may exert long-term effects on the epigenome following maternal exposure.

Effect of different glycation agents on Cu(II) binding to human serum albumin, studied by liquid chromatography, nitrogen microwave-plasma atomic-emission spectrometry, inductively-coupled-plasma mass spectrometry, and high-resolution molecular-mass spectrometry.

The ability of human serum albumin to capture unbound copper under different clinical conditions is an important variable potentially affecting homeostasis of this element. Here, we propose a simple procedure based on size-exclusion chromatography with on-line UV and nitrogen microwave-plasma atomic-emission spectrometry (MP-AES) for quantitative evaluation of Cu(II) binding to HSA upon its glycation in vitro. The Cu-to-protein molar ratio for non-glycated albumin was 0.98 ± 0.09; for HSA modified with glyoxal (GO), methylglyoxal (MGO), oxoacetic acid (GA), and glucose (Glc), the ratios were 1.30 ± 0.22, 0.72 ± 0.14, 0.50 ± 0.06, and 0.95 ± 0.12, respectively. The results were confirmed by using ICP-MS as an alternative detection system. A reduced ability of glycated protein to coordinate Cu(II) was associated with alteration of the N-terminal metal-binding site during incubation with MGO and GA. In contrast, glycation with GO seemed to generate new binding sites as a result of tertiary structural changes in HSA. Capillary reversed-phase liquid chromatography with electrospray-ionization quadrupole-time-of-flight tandem mass spectrometry enabled detection and identification of Cu(II) coordinated to the N-terminal metal-binding site (Cu(II)-DAHK) in all tryptic digests analyzed. This is the first report confirming Cu(II)-DAHK species in HSA by means of high-resolution tandem mass spectrometry, and the first report on the use of MP-AES in combination with chromatographic separation.

High-performance liquid chromatography determination of glyoxal, methylglyoxal, and diacetyl in urine using 4-methoxy-o-phenylenediamine as derivatizing reagent.

Bioanalytical relevance of glyoxal (Go) and methylglyoxal (MGo) arises from their role as biomarkers of glycation processes and oxidative stress. The third compound of interest in this work is diacetyl (DMGo), a component of different food products and alcoholic beverages and one of the small α-ketoaldehydes previously reported in urine. The original idea for the determination of the above compounds by reversed phase high-performance liquid chromatography (HPLC) with fluorimetric detection was to use 4-methoxy-o-phenylenediamine (4MPD) as a derivatizing reagent and diethylglyoxal (DEGo) as internal standard. Acetonitrile was added to urine for matrix precipitation, and derivatization reaction was carried out in the diluted supernatant at neutral pH (40 °C, 4 h); after acidification, salt-induced phase separation enabled recovery of the obtained quinoxalines in the acetonitrile layer. The separation was achieved within 12 min using a C18 Kinetex column and gradient elution. The calibration detection limits for Go, MGo, and DMGo were 0.46, 0.39, and 0.28 µg/L, respectively. Within-day precision for real-world samples did not exceed 6%. Several urine samples from healthy volunteers, diabetic subjects, and juvenile swimmers were analyzed. The sensitivity of the procedure proposed here enabled detection of differences between analyte concentrations in urine from patients at different clinical or exposure-related conditions.

Application of reversed-phase high-performance liquid chromatography with fluorimetric detection for simultaneous assessment of global DNA and total RNA methylation in Lepidium sativum: effect of plant exposure to Cd(II) and Se(IV).

In the present work, application of the previously established reversed-phase liquid chromatography procedure based on fluorescent labeling of cytosine and methylcytosine moieties with 2-bromoacetophenone (HPLC-FLD) is presented for simultaneous evaluation of global DNA and total RNA methylation at cytosine carbon 5. The need for such analysis was comprehended from the recent advances in the field of epigenetics that highlight the importance of non-coding RNAs in DNA methylation and suggest that RNA methylation might play a similar role in the modulation of genetic information, as previously demonstrated for DNA. In order to adopt HPLC-FLD procedure for DNA and RNA methylation analysis in a single biomass extract, two extraction procedures with different selectivity toward nucleic acids were examined, and a simplified calibration was designed allowing for evaluation of methylation percentage based on the ratio of chromatographic peak areas: cytidine/5-methylcytidine for RNA and 2'-deoxycytidine/5-methyl-2'-deoxycytidine for DNA. As a proof of concept, global DNA and total RNA methylation were determined in Lepidium sativum hydroponically grown in the presence of different Cd(II) or Se(IV) concentrations, expecting that plant exposure to abiotic stress might affect not only global DNA but also total RNA methylation. The results obtained showed the increase of DNA methylation in the treated plants up to concentration levels 2 mg L(-1) Cd and 1 mg L(-1) Se in the growth medium. For higher stressors' concentration, global DNA methylation tended to decrease. Most importantly, an inverse correlation was found between DNA and RNA methylation levels (r = -0.6788, p = 0.031), calling for further studies of this particular modification of nucleic acids in epigenetic context.

Natural decrease of dissolved arsenic in a small stream receiving drainages of abandoned silver mines in Guanajuato, Mexico.

Arsenic release from the abandoned mines and its fate in a local stream were studied. Physicochemical parameters, metals/metalloids and arsenic species were determined. One of the mine drainages was found as a point source of contamination with 309 µg L(-1) of dissolved arsenic; this concentration declined rapidly to 10.5 µg L(-1) about 2 km downstream. Data analysis confirmed that oxidation of As(III) released from the primary sulfide minerals was favored by the increase of pH and oxidation reduction potential; the results obtained in multivariate approach indicated that self-purification of water was due to association of As(V) with secondary solid phase containing Fe, Mn, Ca.

Dietary advanced glycation end products restriction diminishes inflammation markers and oxidative stress in patients with type 2 diabetes mellitus.

The augmented consumption of dietary advanced glycation end products (dAGEs) has been associated with increased oxidative stress and inflammation, however, there is insufficient information over the effect on insulin resistance. The objective of the present study is to investigate the effect of dAGEs restriction on tumor necrosis factor-α (TNF-α), malondialdehyde, C-reactive protein (CRP), and insulin resistance in DM2 patients. We carried out a randomized 6 weeks prospective study in two groups of patients: subjects with a standard diet (n = 13), vs low dAGEs (n = 13). At the beginning and the end of study, we collected anthropometric measurements, and values of circulating glucose, HbA1c, lipids, insulin, serum AGEs, CRP, TNF-α and malondialdehyde. Anthropometric measurements, glucose, and lipids were similar in both groups at base line and at the end of the study. Estimation of basal dAGEs was similar in both groups; after 6 weeks it was unchanged in the standard group but in the low dAGEs group decreased by 44% (p<0.0002). Changes in TNF-α levels were different under standard diet (12.5 ± 14.7) as compared with low dAGEs (-18.36 ± 17.1, p<0.00001); changes in malondialdehyde were different in the respective groups (2.0 ± 2.61 and -0.83 ± 2.0, p<0.005) no changes were found for insulin levels or HOMA-IR. In conclusion, The dAGEs restriction decreased significantly TNF-α and malondialdehyde levels.

Application of hydride generation - microwave plasma - atomic emission spectrometry and partial least squares regression for the determination of antimony directly in water and in PET after alkaline methanolysis.

Antimony is present in different types of plastics as a catalyzer residue and/or as a synergistic fire retardant; relatively high concentrations of this element reported in polyethylene terephthalate (PET) bottles and wrappers as well as its migration to the edible products or to different environment compartments are of concern. In this work, Sb determination is such products had been undertaken using hydride generation - microwave plasma - atomic emission spectrometry. To avoid harsh conditions typically reported for the digestion of PET, alkaline methanolysis was introduced whereas water samples were analyzed directly. Another original approach was to perform quantification by partial least squares regression (PLS1), taking spectral data from 2-nm range that comprised two emission lines (217.581 nm and less intense 217.919 nm). For PET, the calibration solutions contained Sb-free digest and covered the Sb concentration range 80-230 µg L-1. For the analysis of water, the calibration range was 0.5-10 µg L-1 and aqueous standard solutions were used. PLS1 provided reliable prediction, eliminating spectral interferences detected in the presence of PET digests and compensating for the spectral changes observed at low Sb concentrations. After standard addition to the real-world samples, the percentage recoveries were in the range 93.8-99.3% and 68-102% for PET and for bottled water, respectively. The method quantification limit for PET was 10 mg kg-1 and for water it corresponded to 0.20 µg L-1. The concentrations of Sb found in the analyzed samples were: 154-279 mg kg-1 for PET bottles and <0.5-5.30 µg L-1 for water.

Effect of melatonin administration on DNA damage and repair responses in lymphocytes of rats subchronically exposed to lead.

Lead exposure induces DNA damage, oxidative stress, and apoptosis, and alters DNA repair. We investigated the effects of melatonin co-administered to rats during exposure to lead. Three doses of lead acetate (10, 50 and 100mg/kg/day) were administered to rats during a 6-week period. Lymphocytes were analyzed. Lead exposure decreased glutathione (GSH) levels in blood, and at doses of 100mg/kg/day and 50mg/kg/day without melatonin, caused high levels of DNA damage, induced apoptosis, and altered DNA repair. Melatonin co-treatment did not attenuate the effects of lead at 100mg/kg/day, indicating that the effect of melatonin on GSH reduction is not sufficient to reduce the genotoxic effects of lead at this high dose. After 6 weeks of treatment, decreased weight gain was observed in high lead-dose groups (100mg/kg/day), with or without melatonin, and in medium-dose groups (50mg/kg/day) with melatonin, compared with the control group. The protective action of melatonin against lead toxicity is dependent on the dose of lead. Further pharmacological studies are needed to determine whether melatonin acts via melatonin membrane receptors on lymphocytes.

Determination of chromium(III) picolinate in dietary supplements by flow injection - electrospray ionization - tandem mass spectrometry, using cobalt(II) picolinate as internal standard.

In this work, a principle of flow injection analysis (FIA) was applied for sample introduction to an electrospray ionization - ion trap mass spectrometer (ESI-ITMS) with the aim to quantify chromium(III) picolinate (CrPic3) in commercial supplements by multiple reaction monitoring, and using cobalt(II) picolinate as internal standard (IS). FIA system was operated with ammonium formate 10 mmol L-1 in methanol-water (1:1, v/v) as a carrier solution at a flow rate 200 µL min-1; 100 µL injections were performed in 2-min intervals. Setting ion transitions m/z 419 â†’ 270 and 304 â†’ 260 for the analyte and IS, respectively, and 100 ms integration time, the method detection and quantification limits 12 ng g-1 and 40 ng g-1 of Cr (as CrPic3) in the air-dried powder. Acetonitrile extracts of the real-world samples presented varying from sample-to-sample chemical composition and IS efficiently compensated for ionization interferences. Mean results from triplicate analysis of four different supplements were obtained with relative standard deviation 0.1-4.0%, indicating acceptable precision. Trueness of the proposed FIA-ESI-ITMS/MS procedure was demonstrated by 95.8-108% percentage recoveries attained in the analysis of the CrPic3-spiked samples. For comparative purposes, total Cr was determined by ICP-MS. The quantitative results obtained indicate the necessity of analytical control of Cr(III) supplements commercially available and demonstrate that the proposed FIA-ESI-ITMS/MS procedure is well-suited for the determination of CrPic3 in such products.