Determination of lithium in dried blood spots and dried plasma spots by graphite furnace atomic absorption spectrometry: Method development, validation and clinical application.

Therapeutic drug monitoring (TDM) has become a standard of care for the mood stabilizer lithium (Li+). Dried Blood Spots (DBS) and Dried Plasma Spots (DPS) are promising alternative sampling strategies for TDM, which allows simple and cost-effective logistics in many settings, particularly in Developing Countries. DBS and DPS are of particular interest to Li + TDM for allowing the estimation of Li + erythrocyte levels. Thus, the aim of this study was to develop and validate an assay for the determination of Li+ in DBS and DPS by Graphite Furnace Atomic Absorption Spectrometry (GFAAS), and to evaluate its application in a clinical setting. Li+ was extracted from one 8 mm DBS disc punch with nitric acid 4.5% and from one 6 mm DPS disc punch with diluent solution (HNO3 1% + Triton 0.1%) and injected into GFAAS. The method was applied to Li + TDM in 43 patients with mood disorder. The assays were linear from 0.10 to 3.0 mEq L-1 (r > 0.99), precise, with CV 3.6-7.2% for DBS and 4.6-9.3% for DPS samples, and accurate, with accuracy values of 97-109% and 98-106% for DBS and DPS samples, respectively. Li+ was stable in dried samples during twenty days at up to 42 °C. The DBS assay accuracy and recovery were not influenced by blood hematocrit. The patients presented Li + serum concentrations of 0.18-1.1 mEq L-1 and 0.17 to 0.92 mEq L-1 in DBS and 0.15 to 0.99 mEq L-1 in DPS samples. DPS had comparable Li + concentrations to the ones found in fresh serum samples. With DBS samples it was possible to estimate the Li + erythrocyte to plasma concentration ratio (LiR). The findings of this study support the clinical application of DBS and DPS samples for the TDM of Li+.

Increase of global DNA methylation patterns in beauty salon workers exposed to low levels of formaldehyde.

Formaldehyde (FA) is a carcinogenic aldehyde illegally added to creams as a hair straightening agent for the Brazilian blowout (BB). This study aimed to investigate the possible effects of occupational exposure to FA on global DNA methylation in salon workers with different exposure levels. FA exposure was monitored using environmental and biological measurements. The study included 49 salon workers divided by FA levels in the workplace into group A (FA < 0.01 ppm; n = 8), group B (0.03 ppm < FA < 0.06 ppm; n = 15), and group C (0.08 ppm < FA < 0.24 ppm; n = 26). The global DNA methylation levels were 3.12%, 4.55%, and 4.29% for groups A, B, and C, respectively, with statistically higher values for groups B and C compared to group A (p = 0.002). A correlation was found between FA in passive samplers and global DNA methylation (rs = 0.307, p = 0.032). Additionally, when only taking into account the hairdressers that performed the BB on clients instead of the whole group, a stronger correlation was observed between FA in personal passive samplers and global DNA methylation (rs = 0.764, p = 0.006). For the first time, an increase in DNA methylation was observed in subjects occupationally exposed to FA. In conclusion, our results indicated that even low levels of FA exposure could cause a disturbance in DNA methylation, leading to epigenetic changes, which is associated with cancer development. These data suggest a possible contribution of FA to cancer development through occupational exposure.

Caffeine levels as a predictor of Human mastadenovirus presence in surface waters-a case study in the Sinos River basin-Brazil.

The presence of caffeine in environmental water samples is almost entirely human-related, given that there are virtually no industrial or agricultural releases. Caffeine has already been proposed as an anthropogenic marker for wastewater contamination of surface waters. The aim of this study was to evaluate if caffeine concentrations in water can be a predictor of virological and bacteriological contamination. Water samples were taken at three sampling sites from urban water streams from the hydrographic basin of the Sinos River (Brazil) monthly in the period of May 9th, 2016 to April 11th, 2017 (n = 36). Concentrations of Human mastadenovirus (HAdV-F and HAdV-C), fecal coliforms, and caffeine were measured in all collected samples. Concentrations of caffeine in water were strongly correlated with HAdV-F (rs = 0.704, p = 0.000). This study, for the first time, characterized caffeine concentrations in water as predictors of virus presence, with cut-off values presenting 92.9% specificity and 95.5% sensitivity for HAdV-F and 66.7% specificity and 80% sensitivity for HAdV-C. Considering its marked chemical stability and ease of quantification, caffeine concentrations can be used as a comprehensive marker of human contamination of water resources, also being predictive of bacteriological and virological concentrations.

Simultaneous determination of fluoxetine and norfluoxetine in dried blood spots using high-performance liquid chromatography-tandem mass spectrometry.

BACKGROUND: Therapeutic drug monitoring (TDM) of the widely prescribed antidepressant fluoxetine (FLU) is recommended in certain situations, such as occurrence of toxicity, inadequate response or suspect of poor adherence. Dried blood spot (DBS) sampling is an increasingly studied alternative for TDM, particularly for outpatients, due to its ease of collection and inherent stability. OBJECTIVES: The aim of this study was to develop and validate an LC-MS/MS assay for the simultaneous quantification of FLU and norfluoxetine (NFLU) in DBS. DESIGN AND METHODS: The assay is based on a liquid extraction of single DBS with 8mm of diameter, using FLU-D6 as the internal standard, followed by reversed phase separation in an Accucore® C18 column (100×2.1mm, 2.6µm). Mobile phase was composed of water and acetonitrile (gradient from 80:20 to 50:50, v/v), both containing formic acid 0.1%. The assay was validated and applied to 30 patients under FLU pharmacotherapy. RESULTS: The assay was linear in the range 10-750ngmL-1. Precision assays presented CV% of 3.13-9.61 and 3.54-7.99 for FLU and NFLU, respectively, and accuracy in the range of 97.98-110.44% and 100.25-105.8%. FLU and NFLU were stable at 25 and 45°C for 7days. The assay was evaluated in 30 patients under FLU treatment. Concentrations of both compounds were higher in DBS than in plasma, and the use of the multiplying factors 0.71 and 0.68 for FLU and NFLU, respectively, allowed acceptable estimation of plasma concentrations, with median prediction bias of -0.55 to 0.55% and mean differences of 0.4 to 2.2ngmL-1. CONCLUSIONS: The presented data support the clinical use of DBS for therapeutic drug monitoring of FLU.

Evaluation of genotoxicity in workers exposed to low levels of formaldehyde in a furniture manufacturing facility.

Formaldehyde (FA) is a chemical widely used in the furniture industry and has been classified as a potential human carcinogen. The purpose of this study was to evaluate the occupational exposure of workers to FA at a furniture manufacturing facility and the relationship between environmental concentrations of FA, formic acid concentration in urine, and DNA damage. The sample consisted of 46 workers exposed to FA and a control group of 45 individuals with no history of occupational exposure. Environmental concentrations of FA were determined by high-performance liquid chromatography. Urinary formic acid concentrations were determined by gas chromatography with flame ionization detector. DNA damage was evaluated by the micronucleus (MN) test performed in exfoliated buccal cells and comet assay with venous blood. The 8-h time-weighted average of FA environmental concentration ranged from 0.03 ppm to 0.09 ppm at the plant, and the control group was exposed to a mean concentration of 0.012 ppm. Workers exposed to higher environmental FA concentrations had urinary formic acid concentrations significantly different from those of controls (31.85 mg L(-1) vs. 19.35 mg L(-), p ≤ 0.01 Mann-Whitney test). Significant differences were found between control and exposed groups for the following parameters: damage frequency and damage index in the comet assay, frequency of binucleated cells in the MN test, and formic acid concentration in urine. The frequency of micronuclei, nuclear buds, and karyorrhexis did not differ between groups. There was a positive correlation between environmental concentrations of FA and damage frequency (Spearman's rank correlation coefficient [r s] = 0.24), damage index (r s = 0.21), binucleated cells (r s = 0.34), and urinary formic acid concentration (r s = 0.63). The results indicate that, although workers in the furniture manufacturing facility were exposed to low environmental levels of FA, this agent contributes to the observed increase in cytogenetic damage. In addition, urinary formic acid concentrations correlated strongly with occupational exposure to FA.

Environmental and biological monitoring of occupational formaldehyde exposure resulting from the use of products for hair straightening.

The evaluation of formaldehyde (FD) exposure in beauty salons, due to the use of hair straightening products, and its relation with genotoxicity biomarkers was performed in this study. Regardless of official recommendations, the inappropriate use of homemade hair creams has became a popular practice in Brazil, and high formaldehyde content in the "progressive straightening" creams can contain mutagens that could increase the incidence of neoplasia in those people who use them. Damage to DNA was assessed by conducting a micronuclei test (MNT) on buccal cells and the comet assay on heparinized venous blood samples. A total of 50 volunteers were recruited at six different beauty salons (labeled A to F). At two salons that used products that did not contain FD (salons D and E), environmental FD concentrations were 0.04 and 0.02 ppm. In contrast, the products used at salons A, B, C, and F contained 5.7, 2.61, 5.9, and 5.79% of FD, and these salons had environmental FD concentrations of 0.07, 0.14, 0.16, and 0.14 ppm, respectively. Comparison of the beauty salon workers from each of the six beauty salons revealed significant differences in urinary formic acid (FA) concentration before exposure (p = 0.016), urinary FA after exposure (p = 0.004), variation in FA concentration before and after exposure (p = 0.018), environmental FD concentration (p < 0.001), cytogenetic damage detected by the comet assay according to both damage index (p < 0.001) and frequency of damage (p < 0.001), and for karyorrhexis only according to the MNT (p = 0.001).

Ultra-high performance liquid chromatography tandem mass spectrometric method for the determination of tamoxifen, N-desmethyltamoxifen, 4-hydroxytamoxifen and endoxifen in dried blood spots--development, validation and clinical application during breast cancer adjuvant therapy.

A LC-MSMS method for the simultaneous determination of tamoxifen, N-desmethyltamoxifen, 4-hydroxytamoxifen and endoxifen in dried blood spots samples was developed and validated. The method employs an ultrasound-assisted liquid extraction and a reversed phase separation in an Acquity(®) C18 column (150×2.1 mm, 1.7 µm). Mobile phase was a mixture of formic acid 0.1% (v/v) pH 2.7 and acetonitrile (gradient from 60:40 to 50:50, v/v). Total analytical run time was 8 min. Precision assays showed CV % lower than 10.75% and accuracy in the range 94.5 to 110.3%. Mean analytes recoveries from DBS ranged from 40% to 92%. The method was successfully applied to 91 paired clinical DBS and plasma samples. Dried blood spots concentrations were highly correlated to plasma, with rs>0.83 (P<0.01). Median estimated plasma concentrations after hematocrit and partition factor adjustment were: TAM 123.3 ng mL(-1); NDT 267.9 ng mL(-1), EDF 10.0 ng mL(-1) and HTF 1.3 ng mL(-1,) representing in average 98 to 104% of the actually measured concentrations. The DBS method was able to identify 96% of patients with plasma EDF concentrations below the clinical threshold related to better prognosis (5.9 ng mL(-1)). The procedure has adequate analytical performance and can be an efficient tool to optimize adjuvant breast cancer treatment, especially in resource limited settings.