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Melamine, its analogues, and aromatic amines (AAs) were commonly detected in a previous study of pregnant women in the Environmental influences on Child Health Outcomes (ECHO) Cohort. While these chemicals have identified toxicities, little is known about their influences on fetal development. We measured these chemicals in gestational urine samples in 3 ECHO cohort sites to assess associations with birth outcomes (n = 1,231). We estimated beta coefficients and 95% confidence intervals (CIs) using adjusted linear mixed models with continuous dilution-standardized concentrations (log 2 transformed and scaled by interquartile range, IQR) or binary indicators for detection. As secondary analyses, we repeated analyses using categorical outcomes. Forty-one of 45 analytes were detected in at least one sample, with > 95 % detection of melamine, cyanuric acid, ammelide, and aniline. Higher melamine concentration was associated with longer gestational age (β^ per IQR increase of log 2 -transformed: 0.082 [95 % CI: -0.012, 0.177]; 2nd vs 1st tertile: 0.173 [-0.048, 0.394]; 3rd vs 1st tertile: 0.186 [-0.035, 0.407]). Similarly in secondary analyses using categorical outcomes, an IQR increase in log 2 (melamine) was associated with 1.22 [0.99, 1.50] higher odds of post-term (>40 & ≤42 weeks) as compared to full-term (≥38 & ≤40 weeks). Several AAs were associated with birthweight and gestational length, with the direction of associations varying by AA. Some stronger associations were observed in females. Our findings suggest melamine and its analogs and AAs may influence gestational length and birthweight., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Melamine tableware can release melamine in daily-use; however, currently there is insufficient evidence to support whether the amount released could pose human exposure risk. We therefore conducted two studies, one is 8-day randomized crossover trial involving 27 volunteers who used melamine and stainless-steel tableware in turn (n = 648) and the other is cross-sectional study including 113 college students and 200 residents (n = 313) to further provide population-based evidence. The crossover study results showed that using melamine tableware could promote urinary concentrations of melamine, cyanuric acid (CYA), and ammelide by 42.1 %, 66.9 %, and 36.2 %, respectively. In the biomonitoring survey, students who are more accessible to melamine tableware in the canteen had 1.47-fold higher median urinary concentrations of melamine-related compounds than that of common residents (393 vs 267 nmol/L, p < 0.01). Additionally, positive associations between exposure to melamine and an oxidative stress indicator, 8-oxo-7,8-dihydroguanine (β = 1.13, 95 % CI: 0.32, 1.94), and CYA and 8-hydroxy-2'-deoxyguanosine (β = 0.87, 95 % CI: 0.22, 1.53) were observed in students (p < 0.01), indicating long-term chronic exposure to these chemicals may induce molecular damage to nucleic acids. Our findings provide compelling evidence that frequent use of melamine tableware continues to be a potential threat to human health., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Melamine caused acute nephrotoxicity in a past food adulteration incident, but it is unclear whether and how widespread ambient exposure to melamine and related compounds might affect pediatric kidney health. We assessed cross-sectional associations between childhood exposure to melamine and its derivatives and biomarkers of kidney injury and health and explored potential heterogeneity by sex suggested by sex-dependent differences in renal physiology. We measured melamine and its derivatives ammeline, ammelide, and cyanuric acid (CYA) in spot urine samples collected from 192 children from an urban site (Seattle, WA) and 187 children from a rural site (Yakima, WA) aged 4-8 years in the Global Alliance to Prevent Prematurity and Stillbirth (GAPPS) Study. In addition, biomarkers of kidney injury were measured in the same urine samples, including albumin, total protein, KIM-1, NAG, NGAL, and EGF. We utilized linear regressions to examine associations between individual chemical exposures and kidney biomarkers. Interaction terms examined association modification by sex, as well as potential interactions between melamine and CYA. Despite comparable exposures, girls had higher levels of many kidney injury biomarkers compared to boys. A ten-fold higher melamine concentration was associated with a 18% (95% CI: 5.6%, 31%) higher EGF in the full sample, while ten-fold higher melamine was associated with a 76% (14.1%, 173%) higher KIM-1 in boys but not in girls (-10.1% (-40.6%, 36.1%), interaction p = 0.026). Melamine exhibited significant negative interactions with CYA in association with total protein and NAG that appeared to be specific to girls. Our results suggest possible associations between melamine exposure and markers of kidney injury that may be more pronounced in boys. These findings provide novel insights into melamine and related derivative compound health effects at low levels of exposure in children and emphasize the role of sex in mediating the relationship between nephrotoxicant exposure and kidney injury., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: All authors report that financial support was provided by National Institutes of Health. All authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Melamine is a high-production-volume chemical and a kidney toxicant. Diet is a key source of melamine exposure, yet little is known about which foods in the US diet may be contaminated. This study evaluated the associations of foods and dietary patterns with melamine exposure using data from 478 US adults and children from the National Health and Nutrition Examination Survey 2003-2004. Melamine concentrations were measured in spot urine samples. Dietary recalls were used to collect dietary data from the day preceding urine collection. Melamine was detectable (>0.09 ng/mL) in 76.2% of the participants' urine. The geometric mean urinary melamine was 11.563 µg/g of creatinine (standard error (SE): 1.235). In adjusted linear regression models, each additional ounce of processed meats or whole grains was associated with 10.6% (95% confidence interval (CI): 2.7, 19.0; p = 0.007) or 17.4% (95% CI: 4.7, 31.7; p = 0.006) greater creatinine-adjusted melamine concentrations, respectively. A dietary pattern characterized by high fruit, whole grain, milk, and yogurt intake was positively associated with melamine exposure. In conclusion, processed meats, whole grains, and possibly other plant-based foods may be important melamine sources in the US. Future research should confirm these findings using more recent data and examine the potential health risks of chronic low-level melamine exposure.

Remdesivir has reported efficacy against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in vitro and in vivo Drug-drug interactions limit therapeutic options in transplant patients. Remdesivir and its metabolite GS-441524 are excreted principally in urine. In intensive care unit (ICU) settings, in which multiple-organ dysfunctions can occur rapidly, hemodialysis may be a viable option for maintaining remdesivir treatment, while improving tolerance, by removing both remdesivir's metabolite (GS-441524) and sulfobutylether β-cyclodextrin sodium (SEBCD). Additional studies may prove informative, particularly in the evaluations of therapeutic options for coronavirus disease 2019 (COVID-19)., (Copyright © 2020 American Society for Microbiology.)

Environmental exposure to melamine has been associated with early renal injury in urolithiasis patients even when urinary concentrations of melamine are low. The aim of this study was to derive a benchmark dose (BMD) for melamine for urolithiasis patients. To do this, one-spot urine sample from 309 participants was obtained to measure urinary melamine and N-acetyl β-D-glucosaminidase (NAG), an early renal damage biomarker. The participants were then classified into four exposure groups based on the outcomes of melamine tableware usage questionnaire. A beta distribution of urinary excretion fraction for each group was assumed to estimate their average daily intakes (AvDIs) of melamine. The BMD and the corresponding one-sided 95% lower bound (BMDL) was then derived based on Bayesian model averaging of alternative regression models between the participants' NAG levels and their estimated AvDIs, adjusting for age, gender, and other covariates. Bayesian Markov chain Monte Carlo simulations were used for all the estimates. With a benchmark response of 0.10, the simulated BMDL of 4.89 μg/kg-bw/day for melamine exposure threshold was much lower than the WHO's current recommended tolerable daily intake of 200 μg/kg&#95;bw/day and the US FDA's 63 μg/kg&#95;bw/day. The current regulation level of melamine might not safeguard urolithiasis patients from further deterioration of renal function., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020. Published by Elsevier Inc.)

Rationale: Melamine is ubiquitously present in our daily life. It has a known effect on the kidneys, but it may also adversely affect the reproduction system. We have developed an analytical method for measuring melamine levels in maternal placenta and correlated these levels with melamine concentrations in urine, a necessary step in finding out if melamine might cross the placenta and enter the circulation of the fetus., Methods: We used liquid-liquid extraction, clean up by solid-phase extraction (SPE), and isotope-dilution liquid chromatography/tandem mass spectrometry (LC/MS/MS) to measure melamine in placenta specimens. The results of this method were assessed for linearity, limits of quantitation (LOQs), and intra- and inter-assay precision as well as accuracy, matrix effect, and recovery rate., Results: Calibration curves indicated good linearity (r >0.995) over concentrations ranging from 5 to 500 ng/mL in placenta specimens, intra- and inter-assay precision from 0.89% to 27.07%, and accuracy from 92.4% to123.5%. Recovery ranged from 63.9 to 83.9%, and the LOQ was 5 ng/mL in placenta (0.2 g). Placental melamine levels ranged from 7.87 to19.64 ng/mL, all detectable (n = 8). Pregnant women with higher levels of urinary melamine had higher placenta melamine levels than those with non-detectable urinary melamine, though the results were not significantly different (p = 0.149, n = 4 in each group)., Conclusions: The results of this study suggest that pregnant women were exposed to low doses of melamine in their daily lives as measured in urine samples and placenta specimens. It is unclear whether placenta melamine concentrations can better represent long-term exposure than urine or whether melamine in the uterus can enter the fetus via this route., (© 2019 John Wiley & Sons, Ltd.)

Background and Objectives: CKD is a global public health problem. Some cross-sectional studies have associated environmental melamine exposure with kidney diseases, but evidence is limited., Design, Setting, Participants, & Measurements: We conducted this prospective cohort study to enroll patients with eGFR≥30 ml/min per 1.73 m 2 in 2006-2010. Urinary corrected melamine levels (ratio of urinary melamine to urinary creatinine) were measured by liquid chromatography/tandem mass spectrometry at enrollment. Kidney outcomes included doubling of serum creatinine levels, eGFR decline >3 ml/min per 1.73 m 2 per year, and 30% decline in eGFR in the first 2 years. Subjects were followed until targeted kidney outcomes, cancer, death, last contact, or the end of observation in December 2016., Results: In a total of 293 subjects, the median urinary corrected melamine level was 0.97 (interquartile range, 0.43-2.08) μ g/mmol. Over a median follow-up period of 7.0 years, serum creatinine levels doubled in 80 subjects (27%). Subjects in the highest tertile of urinary melamine level 12.70 μ g/mmol) had a 2.30 (95% confidence interval, 1.25 to 4.23; P <0.01) hazard risk for doubling of serum creatinine compared with those in the lowest tertile (0.02-0.58 μ g/mmol). Similar significant dose-response results were found in eGFR decline >3 ml/min per 1.73 m 2 per year and 30% decline in eGFR in the first 2 years., Conclusions: Urinary melamine level is significantly associated with kidney function deterioration in patients with early-stage CKD., (Copyright © 2019 by the American Society of Nephrology.)

Following outbreaks of feed and food adulterations with a melamine and cyanuric acid mixture in 2007 and melamine in 2008 respectively, the kinetics and toxicodynamics of the mixture have been investigated particularly in sensitive species such as the rainbow trout. Tissue concentrations and intensity of the adverse effect, melamine-cyanurate crystal formation in kidney, were reported in similar experimental conditions. Here, a recent PBTK model for rainbow trout has been applied to model the kinetics of both single compounds based on residue levels in tissues. Both PBTK models for the single compounds were combined and a model of crystal formation for the mixture melamine-cyanuric acid was also added to predict the intensity of crystal formation under the assumptions that crystals formed either in urine or in kidney tissue. Modelling the kinetics of melamine and cyanuric acid provided a better understanding and prediction of intensity of crystal formation in case of sequential exposures with varying intensity or co-exposure. This study demonstrates, for the first time, how fish PBTK models can play a key role in the understanding and prediction of toxicokinetics and toxicodynamics of mixtures. This study also illustrates how adverse effects may potentially occur even when the compounds are not administered together as a mixture., (Copyright © 2019 Elsevier Inc. All rights reserved.)

1. The absorption, distribution, metabolism and excretion of enasidenib were studied following a single oral dose of [ 14 C]enasidenib to rats (10 mg/kg; 100 μCi/kg) and healthy volunteers (100 mg; 318 nCi). 2. Enasidenib was readily absorbed, extensively metabolized and primarily eliminated via the hepatobiliary pathway. Enasidenib-derived radioactivity was widely distributed in rats. Excretion of radioactivity was approximately 95-99% of the dose from rats in 168 h post-dose and 82.4% from human volunteers in 504 h post-dose. In rat bile, approximately 35-42% of the administered dose was recovered, with less than 5% of the dose excreted as the parent drug. Renal elimination was a minor pathway, with <12% of the dose excreted in rat urine and <10% of the dose excreted in human urine. 3. Enasidenib was the prominent radioactive component in rat and human systemic circulation. Enasidenib was extensively metabolized in rats and human volunteers through N-dealkylation, oxidation, direct glucuronidation and combinations of these pathways. Glucuronidation was the major metabolic pathway in rats while N-dealkylation was the prominent metabolic pathway in human volunteers. All human metabolites were detected in rats.

Melamine is used extensively in household products, such as furniture, dinnerware, and food utensils. Several studies have shown that melamine adversely affects kidney function. Nevertheless, little is known about urinary melamine concentrations, and its temporal variability. In this study, 213 first-morning-void urine samples were collected from 19 volunteers for over a month to assess longitudinal variability in concentrations of melamine and its three structural analogues, i.e., cyanuric acid, ammeline, and ammelide. Target analytes were found in all urine samples at mean concentrations of 3.3, 16, 0.99, and 0.62 ng/mL, for melamine, cyanuric acid, ammelide, and ammeline, respectively. Cyanuric acid was the major compound found in all urine samples, accounting for 74-80% of the total concentrations, followed by melamine (12-20%), ammelide (4-6%), and ammeline (2-4%). Gender- and age-related differences in melamine concentrations were observed, although no such pattern was found for cyanuric acid. After adjusting for creatinine, melamine and cyanuric acid concentrations were moderately predictable with inter-day intraclass correlation coefficients (ICCs) in the range of 0.541-0.763. Nevertheless, substantial inter-individual variation in melamine levels existed even after creatinine adjustment, as evidenced by low ICCs (0.008-0.108). Cumulative daily intake of melamine and cyanuric acid was calculated on the basis of urinary concentrations and the mean values were found to be at least 10-fold below the current tolerable daily intake., (Copyright © 2019. Published by Elsevier Ltd.)

In this open-label study (NCT02142920), we investigated the distribution, pharmacokinetics, and metabolism of the pan-class-I isoform phosphatidylinositol 3-kinase/mammalian target of rapamycin inhibitor gedatolisib (PF-05212384), following a single intravenous administration in healthy male subjects. A single, 89-mg, intravenous dose of gedatolisib was associated with a favorable safety profile in the 6 healthy subjects evaluated. Peak plasma concentrations for unchanged gedatolisib and total radioactivity were observed at the end of the 30-minute infusion. The only observed drug-related material in plasma was the parent drug, gedatolisib. Terminal half-life for plasma gedatolisib was ∼37 hours. Following the dose, 66%-73% of drug-related material was recovered in the feces. Metabolism of gedatolisib was trace; only 1 oxidative metabolite, M5, was identified in feces (<1% of total dose). Identification of gedatolisib in feces suggests that biliary and/or intestinal secretion of unchanged parent drug significantly contributes to gedatolisib clearance., (© 2018, The American College of Clinical Pharmacology.)

Swimming pool water ingestion volumes are necessary for assessing infection risk from swimming. Pool water ingestion volumes can be estimated by questionnaire or measuring a chemical tracer in swimmer urine. Questionnaires are often preferred to the chemical tracer method because surveys are less time consuming, but no research exists validating questionnaires accurately quantify pool water ingestion volumes. The objective of this study was to explore if questionnaires are a reliable tool for collecting pool water ingestion volumes. A questionnaire was issued at four pool sites in Tucson, Arizona to 46 swimmers who also submitted a urine sample for analyzing cyanuric acid, a chemical tracer. Perceived ingestion volumes reported on the questionnaire were compared with pool water ingestion volumes, quantified by analyzing cyanuric acid in swimmer urine. Swimmers were asked if they swallowed (1) no water or only a few drops, (2) one to two mouthfuls, (3) three to five mouthfuls, or (4) six to eight mouthfuls. One mouthful is the equivalent of 27 mL of water. The majority (81%) of swimmers ingested <27 mL of pool water but reported ingesting >27 mL ("one mouthful") on the questionnaire. More than half (52%) of swimmers overestimated their ingestion volume. These findings suggest swimmers are over-estimating pool water ingestion because they perceive one mouthful is <27 mL. The questionnaire did not reliably collect pool water ingestion volumes and should be improved for future exposure assessment studies. Images of the ingestion volume categories should be included on the questionnaire to help swimmers visualize the response options.

Melamine is a nitrogen-containing organic compound that is used in a wide range of products, including paints, plastics, and paper, as a flame retardant. A few studies have reported the occurrence of melamine and its derivatives in pet food, following a number of deaths of cats and dogs from kidney failure in 2007, which was attributed to melamine contamination in ingredients used in pet food. Nevertheless, studies that report the occurrence of melamine and its derivatives in pet urine are scarce. In this study, we measured melamine and its derivatives (i.e., ammeline, ammelide, and cyanuric acid) in dog (n = 30) and cat (n = 30) urine collected from Albany, New York, USA, during March through July 2017. The mean (±SD) concentrations of melamine, ammeline, ammelide, and cyanuric acid in dog urine were 21.1 ± 51.2, 2.3 ± 3.8, 9.9 ± 1 0.4, and 79.0 ± 105 ng/mL, respectively; the corresponding concentrations in cats were 21.4 ± 26.1, 1.2 ± 2.5, 6.1 ± 3.9, and 105 ± 94.6 ng/mL, respectively. No significant difference was observed in urinary concentrations of melamine derivatives between cats and dogs. Age and gender were important determinants of the concentrations of the target chemicals in cats and dogs. Cumulative daily intake of melamine and its derivatives was calculated on the basis of urinary concentrations and was found to be 10-500-fold below the tolerable daily intake., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Biological monitoring of occupational exposure to 1,6-hexamethylene diisocyanate (HDI)-containing spray-paints is limited to analysis of metabolites of HDI monomer although polymeric HDI isocyanurate constitutes the predominant inhalation and skin exposure for workers in the automotive paint industry. A novel method using nanoflow ultra-performance liquid chromatography coupled to nano-electrospray ionization tandem mass spectrometry (nano-UPLC-ESI-MS/MS) was developed to quantify trisaminohexyl isocyanurate (TAHI), a hydrolysis product of HDI isocyanurate, in the urine of spray-painters. Analytical and internal standards were synthesized in-house and weighted linear regression calibration curves were generated using spiked control urine from non-exposed persons (0.06-7.98 μg/L; N = 13; w = x -2 ; r = 0.998). Urine samples collected from 15 exposed workers (N = 111) were subjected to acid hydrolysis and extracted with dichloromethane, then derivatized with acetic anhydride. The derivatized product, trisacetamidohexyl isocyanurate (TAAHI), was analyzed using nano-UPLC-ESI-MS/MS. The protocol was sensitive and specific for analysis of TAHI in the urine of exposed workers with a method detection limit at 0.03 μg/L. TAHI was detected in 33 of 111 urine samples and in 11 of 15 workers. This biomarker for HDI isocyanurate is critical to determine the relative potency and dose-relationships between the monomer and oligomer exposure on the development of diisocyanate induced health effects in future studies., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Environmental low-dose melamine exposure has been associated with urolithiasis risk in adults, but it is unclear if this exposure can cause early renal damage. This cross-sectional study investigated the association of this exposure and early renal damage in patients with calcium urolithiasis. We recruited patients diagnosed with upper urinary tract calcium urolithiasis from three hospitals in southwestern Taiwan between November 2010 and January 2015. All patients completed a structured questionnaire and provided one-spot urine samples for the measurement of melamine level and markers of early renal injury, including N-acetyl b-d-glucosaminidase (NAG), β2-microglobulin (β2-MG), and microalbumin. We used urinary melamine levels as an indicator of environmental melamine exposure. A total of 309 patients (mean age of 54.7 ± 12.8 years) were studied. Median urinary melamine level (μg/mmol Cr) was 1.26 (interquartile range 0.48-3.29). A significant and positive correlation was found between urinary melamine concentration and urinary NAG levels (Spearman correlation coefficient, r = 0.157, p = 0.006, n = 309). With urinary melamine levels categorized into quartiles, multivariate regression results showed the same relationship, particularly in those with first stone episode. In this group, patients with the highest quartile of urinary melamine concentration had a 3.95-fold risk (95% confidence interval = 1.43-10.94) of high NAG levels (dichotomized by median), compared to the lowest quartile after adjustment. No association was found between urinary melamine concentration and urinary microalbumin levels. In conclusion, urinary melamine is significantly associated with urinary marker of early renal tubular injury, NAG, in urolithiasis patients, especially ones with first stone episode., (Copyright © 2017. Published by Elsevier Ltd.)

Terbuthylazine is a selective pre- and post-emergency chloro-triazine herbicide used for a broad spectrum of weed control. We evaluated the potential of low doses of terbuthylazine to induce oxidative stress and cytogenetic damage in peripheral blood samples of adult male Wistar rats. Following 28-day repeated oral exposure at 0.004 mg/kg b.w./day, 0.4 mg/kg b.w./day and 2.29 mg/kg b.w./day, parameters of lipid peroxidation, total antioxidant capacity, and activities of antioxidant enzymes were measured in blood samples. Alkaline comet assay on leukocytes and erythrocyte micronucleus assay were used to measure DNA damage. In addition, the concentration of terbuthylazine and its metabolite in urine and plasma were determined using high performance liquid chromatography with UV diode-array detector (HPLC-UV-DAD). The fraction of terbuthylazine excreted in urine was negligible and was not found in plasma. Deethylterbuthylazine was only compound detected in plasma samples. Exposure to terbuthylazine did not induce significant lipid peroxidation products. The significant changes in antioxidant enzyme activities and the elevated total antioxidant capacity indicated that terbuthylazine at experimental conditions applied has potential to disturb oxidative/antioxidant balance. Results regarding the alkaline comet assay as well as micronucleated reticulocyte frequency indicated that treatment led to low-level DNA instability. Our results call for further research using other sensitive biomarkers of effect, along with different exposure scenarios., (Copyright © 2017. Published by Elsevier Ltd.)

The use of cyanuric acid as a biomarker for ingestion of swimming pool water may lead to quantitative knowledge of the volume of water ingested during swimming, contributing to a better understanding of disease resulting from ingestion of environmental contaminants. When swimming pool water containing chlorinated cyanurates is inadvertently ingested, cyanuric acid is excreted quantitatively within 24 h as a urinary biomarker of ingestion. Because the volume of water ingested can be quantitatively estimated by calculation from the concentration of cyanuric acid in 24 h urine samples, a procedure for preservation, cleanup, and analysis of cyanuric acid was developed to meet the logistical demands of large scale studies. From a practical stand point, urine collected from swimmers cannot be analyzed immediately, given requirements of sample collection, shipping, handling, etc. Thus, to maintain quality control to allow confidence in the results, it is necessary to preserve the samples in a manner that ensures as quantitative analysis as possible. The preservation and clean-up of cyanuric acid in urine is complicated because typical approaches often are incompatible with the keto-enol tautomerization of cyanuric acid, interfering with cyanuric acid sample preparation, chromatography, and detection. Therefore, this paper presents a novel integration of sample preservation, clean-up, chromatography, and detection to determine cyanuric acid in 24 h urine samples. Fortification of urine with cyanuric acid (0.3-3.0 mg/L) demonstrated accuracy (86-93% recovery) and high reproducibility (RSD < 7%). Holding time studies in unpreserved urine suggested sufficient cyanuric acid stability for sample collection procedures, while longer holding times suggested instability of the unpreserved urine. Preserved urine exhibited a loss of around 0.5% after 22 days at refrigerated storage conditions of 4 °C., (Published by Elsevier B.V.)

The volume of water ingested by swimmers while swimming is of great interest to individuals who develop risk assessments using quantitative microbial risk assessment or epidemiological approaches. We have used chloroisocyanurate disinfected swimming pool waters to determine the amount of water swallowed by swimmers during swimming activity. The chloroisocyanurate, which is in equilibrium with chlorine and cyanuric acid in the pool water, provides a biomarker, cyanuric acid, that once swallowed passes through the body into the urine unchanged. The concentration of cyanuric acid in a 24 hour urine specimen and the concentration in pool water can be used to calculate the amount of water swallowed. Our study population of 549 participants, which was about evenly divided by gender, and young and adult swimmers, indicated that swimmers ingest about 32 mL per hour (arithmetic mean) and that children swallowed about four times as much water as adults during swimming activities. It was also observed that males had a tendency to swallow more water than females during swimming activity and that children spent about twice as much time in the water than adults.

Aim: Fotagliptin is a novel dipeptidyl peptidase IV inhibitor under clinical development for the treatment of Type II diabetes mellitus. The objective of this study was to develop and validate a specific and sensitive ultra-performance liquid chromatography (UPLC)-MS/MS method for simultaneous determination of fotagliptin and its two major metabolites in human plasma and urine. Methodology & results: After being pretreated using an automatized procedure, the plasma and urine samples were separated and detected using a UPLC-ESI-MS/MS method, which was validated following the international guidelines., Conclusion: A selective and sensitive UPLC-MS/MS method was first developed and validated for quantifying fotagliptin and its metabolite in human plasma and urine. The method was successfully applied to support the clinical study of fotagliptin in Chinese healthy subjects.

The melamine contaminated milk powder contamination scandal occurred in China in 2008. Its main consequences so far have been urinary stone formation in children with associated renal damage and increased child mortality. Eight years have passed, but food safety issues still remain of concern in the daily lives of millions of Chinese. Vigilance is required to ensure no recurrence of such food safety problems. Ongoing studies focus on the early detection of food industry malpractice, mechanisms whereby these toxic substances induce disease and how its advent may be prevented and better managed. Melamine undergoes renal excretion, but is metabolized slowly and excreted largely unchanged in the urine. Urinary melamine measurement may provide a rapid and inexpensive way to identify exposure to melamine adulterated food items. Although most patients with melaminerelated urinary stones (MUS) have been responsive to conservative treatment, longer time follow-up is needed to assess chronic effects. Aside from MUS, melamine is a recognized carcinogen and can induce urinary tract tumours. Very little is known about the effects of excessive exposure to melamine contaminated milk powder in infants on growth, adolescent and adult health, although short-term effects have become apparent during the scandal.

A new simple methodology is proposed for chlorsufuron (CS) traces quantification based upon enhancement of rhodamine B (RhB) fluorescent signal. Experimental variables that influence fluorimetric sensitivity have been studied and optimized. The zeroth order regression calibration was linear from 0.866 to 35.800µgL(-1) CS, with a correlation coefficient of 0.99. At optimal experimental conditions, a limit of detection of 0.259µgL(-1) and a limit of quantification of 0.866µgL(-1) were obtained. The method showed good sensitivity and adequate selectivity and was applied to the determination of trace amounts of CS in plasma, serum and water samples with satisfactory results analyzed by ANOVA test. The proposed methodology represents an alternative to traditional chromatographic techniques for CS monitoring in complex samples, using an accessible instrument in control laboratories., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Aim: Patients receiving lamotrigine therapy frequently use paracetamol concomitantly. While one study suggests a possible, clinically relevant drug-drug interaction, practical recommendations of the concomitant use are inconsistent. We performed a systematic pharmacokinetic study in healthy volunteers to quantify the effect of 4 day treatment with paracetamol on the metabolism of steady-state lamotrigine., Methods: Twelve healthy, male volunteers participated in an open label, sequential interaction study. Lamotrigine was titrated to steady-state (100 mg daily) over 36 days, and blood and urine sampling was performed in a non-randomized order with and without paracetamol (1 g four times daily). The primary endpoint was change in steady-state area under the plasma concentration-time curve of lamotrigine. Secondary endpoints were changes in total apparent oral clearance, renal clearance, trough concentration of lamotrigine and formation clearance of lamotrigine glucuronide conjugates., Results: Co-administration of lamotrigine and paracetamol decreased the steady-state area under the plasma concentration-time curve of lamotrigine by 20% (95% CI 10%, 25%; P < 0.001) from 166 to 127 μmol l(-1) . Concomitant administration of paracetamol increased the formation clearance of lamotrigine glucuronide conjugates by 45% (95% CI 18%, 79%, P = 0.005) from 1.7 to 2.8 l h(-1) , while the trough value of lamotrigine was reduced by 25% (95% CI 12%, 36%, P = 0.003) from 5.3 to 3.9 μmol l(-1) ., Conclusion: Paracetamol statistically significantly induced steady-state lamotrigine glucuronidation, resulting in a 20% decrease in total systemic exposure and a 25% decrease in trough value of lamotrigine. This interaction may be of clinical relevance in some patients., (© 2015 The British Pharmacological Society.)

The previously-published physiologically based pharmacokinetic model for atrazine (ATZ), deisopropylatrazine (DIA), deethylatrazine (DEA), and diaminochlorotriazine (DACT), which collectively comprise the total chlorotriazines (TCT) as represented in this study, was modified to allow for scaling to humans. Changes included replacing the fixed dose-dependent oral uptake rates with a method that represented delayed absorption observed in rats administered ATZ as a bolus dose suspended in a methylcellulose vehicle. Rate constants for metabolism of ATZ to DIA and DEA, followed by metabolism of DIA and DEA to DACT were predicted using a compartmental model describing the metabolism of the chlorotriazines by rat and human hepatocytesin vitro Overall, the model successfully predicted both the 4-day plasma time-course data in rats administered ATZ by bolus dose (3, 10, and 50 mg/kg/day) or in the diet (30, 100, or 500 ppm). Simulated continuous daily exposure of a 55-kg adult female to ATZ at a dose of 1.0 µg/kg/day resulted in steady-state urinary concentrations of 0.6, 1.4, 2.5, and 6.0 µg/L for DEA, DIA, DACT, and TCT, respectively. The TCT (ATZ + DEA + DIA + DACT) human urinary biomonitoring equivalent concentration following continuous exposure to ATZ at the chronic point of departure (POD = 1.8 mg/kg/day) was 360.6 μg/L., (© The Author 2016. Published by Oxford University Press on behalf of the Society of Toxicology.)

Cyanuric acid (CYA) excretion in urine has been used to estimate the volume of water ingested during swimming and other recreational activities in outdoor pools containing this chemical. These estimates of water ingestion are based on the assumption of 100% excretion within 24 hours, but the supporting evidence for this is scant. While adapting this methodology to investigate other water ingestion scenarios, we observed a high degree of variability in cyanuric acid excretion among experimental subjects, with over 25% of individuals excreting less than 80% of an ingested dose. Use of cyanuric acid to measure inadvertent water ingestion may be a valuable tool to generate data for health risk assessment of non-potable water sources, but our observations indicate that this technique carries an inherent degree of underestimation that should be taken into account when calculating water exposure.

Wastewater and surface water samples, extracted with four solid-phase extraction cartridges of different chemistries, were suspect-screened for the anticonvulsant lamotrigine (LMG), its metabolites, and related compounds. LMG, three human metabolites, and a LMG synthetic impurity (OXO-LMG) were detected. Preliminary results showed significantly higher concentrations of OXO-LMG in wastewater effluent, suggesting its formation in the wastewater treatment plants (WWTPs). However, biodegradation experiments with activated sludge demonstrated that LMG is resistant to degradation and that its human metabolite lamotrigine-N(2)-glucuronide (LMG-N2-G) is the actual source of OXO-LMG in WWTPs. In batch reactors, LMG-N2-G was transformed, following pseudo-first-order kinetics to OXO-LMG and LMG, but kinetic experiments suggested an incomplete mass balance. A fragment ion search applied to batch-reactor and environmental samples revealed another transformation product (TP), formed by LMG-N2-G oxidation, which was identified by high-resolution mass spectrometry. Accounting for all TPs detected, a total mass balance at two concentration levels in batch reactors was closed at 86% and 102%, respectively. In three WWTPs, the total mass balance of LMG-N2-G ranged from 71 to 102%. Finally, LMG-N2-G and its TPs were detected in surface water samples with median concentration ranges of 23-139 ng L(-1). The results of this study suggest that glucuronides of pharmaceuticals might also be sources of yet undiscovered, but environmentally relevant, transformation products.

Through precipitation polymerization, three monodisperse molecularly imprinted polymers (MIPs) containing imprints of 2,4-diamino-6-methyl-1,3,5-triazine (DM), cyromazine (CY) or trimethoprim (TM), were synthesized using methacrylic acid as functional monomer, divinylbenzene as cross-linker, and a mixture of acetonitrile-toluene (90/10, v/v) as porogen. The morphology and selectivity of the MIPs were characterized and compared systematically. The MIPs had the best specific binding in pure acetonitrile, and the data of adsorption experiment were fitted well with Langmuir and Freundlich model. In addition, DM-MIPs showed the excellent binding and multi-recognition capability for CY, melamine (ME), triamterene (TA) and TM, and the binding capacity were 7.18, 7.56, 5.66 and 5.45μmol/g, respectively. Due to the pseudo template and the ability of multi-recognition, DM-MIPs as sorbent material could avoid the effect of template leakage on quantitative analysis. Therefore, DM-MIPs were used as a solid-phase extraction material to enrich ME, CY, TA and TM from different bio-matrix samples for high performance liquid chromatography analysis. Under the optimized conditions, the recoveries of three spiked levels in different bio-matrix samples were ranged from 80.9% to 91.5% with RSD≤4.2 (n=3)., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Chlorazanil (Ordipan, N-(4-chlorophenyl)-1,3,5-triazine-2,4-diamine) is a diuretic agent and as such prohibited in sport according to the regulations of the World Anti-Doping Agency (WADA). Despite its introduction into clinical practice in the late 1950s, the worldwide very first two adverse analytical findings were registered only in 2014, being motive for an in-depth investigation of these cases. Both individuals denied the intake of the drug; however, the athletes did declare the use of the antimalarial prophylactic agent proguanil due to temporary residences in African countries. A structural similarity between chlorazanil and proguanil is given but no direct metabolic relation has been reported in the scientific literature. Moreover, chlorazanil has not been confirmed as a drug impurity of proguanil. Proguanil however is metabolized in humans to N-(4-chlorophenyl)-biguanide, which represents a chemical precursor in the synthesis of chlorazanil. In the presence of formic acid, formaldehyde, or formic acid esters, N-(4-chlorophenyl)-biguanide converts to chlorazanil. In order to probe for potential sources of the chlorazanil detected in the doping control samples, drug formulations containing proguanil and urine samples of individuals using proguanil as antimalarial drug were subjected to liquid chromatography-high resolution/high accuracy mass spectrometry. In addition, in vitro simulations with 4-chlorophenyl-biguanide and respective reactants were conducted in urine and resulting specimens analyzed for the presence of chlorazanil. While no chlorazanil was found in drug formulations, the urine samples of 2 out of 4 proguanil users returned findings for chlorazanil at low ng/mL levels, similar to the adverse analytical findings in the doping control samples. Further, in the presence of formaldehyde, formic acid and related esters, 4-chlorophenyl-biguanide was found to produce chlorazanil in human urine, suggesting that the detection of the obsolete diuretic agent was indeed the result of artefact formation and not of the illicit use of a prohibited substance., (Copyright © 2015 Elsevier B.V. All rights reserved.)

This study aims to examine whether behavior intervention can decrease total urinary melamine excretion. A total of 16 healthy subjects were recruited from two university buildings (eight subjects each). By using a stepped-wedge cluster randomized and controlled trial design, we randomly assigned eight subjects from the same building to the serial steps of either control-intervention-intervention or control-control-intervention. Each step lasted for 3 days. Subjects in the intervention step carried one bag containing stainless steel tableware as meal boxes and used them for each meal during the trial, whereas those in the control step carried one empty bag. The 24 h urine samples for 9 consecutive days were collected. In the control-intervention-intervention group, after excluding two subjects with missing data, the median absolute difference of the total 3 day melamine excretion between the seventh to the ninth day and from the first to the third day was -19.9 μg (a range from -160.6 to -7.2 μg, p = 0.028, n = 6). The median protection percent of the total 3 day melamine exposure (the amount from the seventh to the ninth day minus the amount from the first to the third day, divided by the amount from the first to the third day) was 68.4%, ranging from 41.8% to 91.8%. Regular use of stainless steel-made meals boxes can mitigate melamine exposure from melamine tableware.

A novel and simple method based on solidified floating organic drop microextraction followed by high-performance liquid chromatography with ultraviolet detection has been developed for simultaneous preconcentration and determination of phenobarbital, lamotrigine, and phenytoin in human plasma and urine samples. Factors affecting microextraction efficiency such as the type and volume of the extraction solvent, sample pH, extraction time, stirring rate, extraction temperature, ionic strength, and sample volume were optimized. Under the optimum conditions (i.e. extraction solvent, 1-undecanol (40 μL); sample pH, 8.0; temperature, 25°C; stirring rate, 500 rpm; sample volume, 7 mL; potassium chloride concentration, 5% and extraction time, 50 min), the limits of detection for phenobarbital, lamotrigine, and phenytoin were 1.0, 0.1, and 0.3 μg/L, respectively. Also, the calibration curves for phenobarbital, lamotrigine, and phenytoin were linear in the concentration range of 2.0-300.0, 0.3-200.0, and 1.0-200.0 μg/L, respectively. The relative standard deviations for six replicate extractions and determinations of phenobarbital, lamotrigine, and phenytoin at 50 μg/L level were less than 4.6%. The method was successfully applied to determine phenobarbital, lamotrigine, and phenytoin in plasma and urine samples., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Magnetic molecularly imprinted polymers have been synthesized for the selective preconcentration and trace determination of lamotrigine (LTG) in urine and plasma samples. The magnetic nanoparticles were modified by tetraethyl orthosilicate and 3-methacryloxypropyl trimethoxysilane before imprinting. The magnetic molecularly imprinted polymers were prepared via surface molecular imprinting technique, using Fe3 O4 as a magnetic component, LTG as template molecule, methacrylic acid as a functional monomer, ethylene glycol dimethacrylate as a cross-linker, and 2,2'-azobisisobutyronitrile as a radical initiator in methanol/acetonitrile (50:50, v/v) as the porogen. The obtained sorbent was characterized using scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, and thermal analysis. Separation of the sorbent from the sample solution was simply achieved by applying an external magnetic field. Determination of the extracted drug was performed by high-performance liquid chromatography with UV detection. Under the optimum extraction conditions, the method detection limits were 0.7 μg/L (based on S/N of 3) for urine samples and 0.5 μg/L for plasma samples. A linear dynamic range of 1-1000 μg/L was obtained for LTF in plasma and urine samples. Finally, the applicability of the proposed method was evaluated by extraction and determination of LTG in urine and plasma samples., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Enteric pathogens in pool water can be unintentionally ingested during swimming, increasing the likelihood of acute gastrointestinal illness (AGI). AGI cases in outbreaks are more likely to submerge heads than non-cases, but an association is unknown since outbreak data are self-reported and prone to bias. In the present study, head submersion frequency and duration were observed and analyzed for associations with pool water ingestion measured using ultra high pressure liquid chromatography - tandem mass spectrometry. Frequency of splashes to the face was also quantified. Reliable tools that assess activities associated with pool water ingestion are needed to identify ingestion risk factors and at-risk populations. Objectives were to determine if the observed activities were associated with ingestion, and to test environmental sensor and videography assessment tools. Greater frequency and duration of head submersion were not associated with ingestion, but frequency of splashes to the face, leisurely swimming, and being ≤18 were. Videography was validated for assessing swimmer head submersion frequency. Results demonstrate ingestion risk factors can be identified using videography and urine analysis techniques. Expanding surveys to include questions on leisure swimming participation and frequency of splashes to the face is recommended to improve exposure assessment during outbreak investigations.

Melamine is widely being reported as a food adulterant. Although its toxicity is currently recognized, melamine adulterations of food items are ongoing for falsely inflating the protein content of the food. Melamine alone or in combination with cyanuric acid or uric acid causes nephrotoxicity, and melamine-induced nephrotoxicity is now a global concern. It has been proven that when consumed, melamine is metabolized at a slower rate and excreted unchanged in urine. There is every possibility that when individuals consume melamine-adulterated food items, the melamine may be excreted unchanged in the urine. Therefore, melamine estimation in urine may be a yardstick to check for melamine adulteration of food items. In the present review, recent literature on this subject is analyzed justifying., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Herbicides are generally the most extensively used of the pesticides applied to agricultural crops. However, the literature contains little evidence useful in assessing the potential sources of the general population's exposure to herbicides, including by residential proximity to crops. The objective of this study was to take advantage of data from the PELAGIE mother-child cohort to identify the main determinants of the body burden of exposure to the chloroacetanilide and triazine herbicides commonly used on corn crops in Brittany, France, before 2006. Urine samples from a randomly selected subcohort of women in the first trimester of pregnancy (n=579) were assayed for herbicide metabolites. The residential exposure resulting from proximity to corn crops was assessed with satellite-image-based scores combined with meteorological data. Data on diet, drinking tap water (from the public water supply), occupations, and household herbicide use were collected by questionnaires. Herbicides were quantified in 5.3% to 39.7% of urine samples. Alachlor and acetochlor were found most frequently in the urine of women living in rural areas. The presence of dealkylated triazine metabolites in urine samples was positively associated with residential proximity to corn crops (OR=1.38, 95% CI: 1.05-1.80). Urinary metabolites of both atrazine and dealkylated triazine were correlated with tap water consumption (OR=2.94, 1.09-7.90, and OR=1.82, 1.10-3.03, respectively); hydroxylated triazine metabolites were correlated with fish intake (OR=1.48, 1.09-1.99). This study reinforces previous results that suggest that environmental contamination resulting from agricultural activities may contribute to the general population's exposure to herbicides., (© 2013.)

The illegal food additives including ractopamine and melamine throw a serious threat to human health. In this paper, the ractopamine and melamine were first used to form the nanochain structure of citrate-stabilized gold nanoparticles (AuNPs) with a convenient and inexpensive method. The fabricated nanochain structure consisting of several AuNPs was characterized by Scanning Electron Microscopy. A new longitudinal surface plasma resonance, which could be adjusted from visible to near infrared range, was observed in absorption spectra due to the aggregation of AuNPs. This could be well explained by Finite Different Time Domain algorithm theoretically. As confirmed by Fourier Transform Infrared Spectroscopy, the complex formed by hydrogen-bonding interaction between melamine and ractopamine could effectively promote the aggregation of AuNPs that was useful to develop the sensitivity and selectivity for the detection of ractopamine. Hence, the plasmonic coupling phenomenon of gold nanochain could be applied in bio-assay for ractopamine through the change of solution's color and optical absorption band with naked eye or absorption spectra. The linear range was broadened to (1.23 × 10(-7)M, 1.11 × 10(-6)M) and the limit of detection was extended to 4.10 × 10(-8)M (S/N=3). More importantly, this time-saving method will be promising in rapid and selective detection of β-agonist for clinical applications., (Crown Copyright © 2013 Published by Elsevier B.V. All rights reserved.)

The aim of this work was to evaluate short-term and long-term exposure to terbuthylazine (TBA) in agriculture workers (AW), rural residents (RR), and urban residents (UR) using urine and hair specimens. Twelve AW, 13 RR, and 17 UR were included in the study. Urine spot samples were collected with two different protocols. AW urine samples were collected before the application season (February, U0), at bedtime on the day of TBA application (March-May, U1), and prior to the next shift on the day after TBA application (U2). RR and UR urine samples were collected on any day during the application season (Ue). Hair samples were collected for all subjects before the application season (February, H0) and at the end of the season (June, H1). TBA and its metabolite desethylterbuthylazine (DET) were measured by liquid chromatography coupled with triple quadrupole mass spectrometry detection. DET was exclusively found in urine, while TBA was mostly found in the hair. In the AW, the urinary levels of DET were not detected in the U0 samples, and they increased to median levels of 1.81 and 2.94μg/L in the U1 and U2 samples, respectively (p<0.001). In the RR and UR, DET was not detected in the Ue samples. In the UR, TBA was not detected in the H0 samples, and the median levels of TBA were 0.01ng/mg hair in both the AW and RR. In the H1 samples, the median TBA levels were not detected, 0.01, and 0.08ng/mg hair in the UR, RR, and AW, respectively (p<0.001). Urinary DET and hair TBA are promising candidates for biomonitoring short- and long-term exposure to TBA. The use of this herbicide in agriculture leads to exposure in rural residents., (© 2013.)

Objective: We aimed to establish a sensitive quantified method for the simultaneous determination of melamine and cyanuric acid residues in water and urine by hydrophilic interaction liquid chromatography coupled with electrospray tandem mass spectrometry (HILIC-ESI-MS/MS) with the pretreatment of hydrophilic functional silica gel and cation exchange resin mixed solid phase extraction column(MCT), and to investigate the melamine and cyanuric acid residues in 501 water and 216 urine from several province and city., Methods: About 100 ml water (or 10 ml urine) was adjusted to pH 3.0 with concentrated hydrochloric acid, and then mixed with the internal standard solution((15)N3-melamine and (15)N3-(13)C3 -cyanuric acid) and 100 ml acetonitrile (10 ml for urine). The solution was cleaned with MCT solid-phase extraction column, and eluted once by 3 ml methanol and twice by 2.5 ml methanol (containing 5% ammonia water). The effluent was collected and dried by N2 flow at 40 °C, and then diluted to 2 mmol/L ammonium acetate containing 90% volume fraction acetonitrile. The completely dissolved solution was then filtered with 0.22 µm organic membrane; and the filtrate was detected by high performance liquid chromatography-tandem mass spectrometry and quantified with internal standards. The repeatability and sensitivity of the assay were evaluated. Then we detected the melamine and cyanuric acid residues in 501 water and 216 urine samples collected from several province and city., Results: By the quantification of internal standard (15)N3-melamine and (15)N3-(13)C3-cyanuric acid, the melamine and cyanuric acid were linear in the range of 2.0-1000.0 µg/L with correlation coefficient of 0.9998 and 0.9997. The detection limits of the method were separately 0.4 ng/L (melamine) and 0.3 ng/L (cyanuric acid) for water, and 4.0 ng/L (melamine) and 3.0 ng/L (cyanuric acid) for urine. The average recovery rate was around 95.3%-100.1% with the relative standard deviation (RSD) was <4.02%. Out of the 501 water samples, melamine was detected out in 19.9% (100/501) and cyanuric acid was detected out in 5.2% (26/501). The content was around 0.03-5.00 g/L. Melamine or cyanuric acid was detected out in 24.5% of the urine samples (53/216), with the content around 0.01-1.00 g/L., Conclusion: The established method of solid phase extraction-hydrophilic interaction liquid chromatography-electrospray tandem mass spectrometry can satisfy the requirement for detection of melamine and cyanuric acid residues in all sorts of water and urine. Meanwhile, the two substances widely existed in water and Chinese population.

Background: We investigated whether melamine concentrations in 1-spot overnight urine sample can represent the previous 8- and 24-h total urinary melamine excretions in school children. The relationship between urinary melamine levels and several clinical biomarkers of early renal injury such as microalbumin and N-acetyl-beta-D-glucosaminidase (NAG) in urine was also examined., Methods: School children, aged 6-10 y, and their parents who were healthy and lived closely to Kaohsiung Medical University-affiliated hospitals were recruited. All study children had the first 1-spot overnight urine sample collected on the Sunday morning (the first day) immediately when they woke up, and then all the subsequent urine samples continued to be collected until the first 1-spot overnight urine sample on the morning of the next day (Monday, the second day). Two first 1-spot overnight urine samples from their parents on the same Sunday and Monday mornings were also collected. This protocol was completed in the July and August of 2011. All urine samples were measured for melamine, biomarkers of early renal injury, and creatinine., Results: There were 7 girls and 16 boys in this study. Except for one missing urine sample from 1-spot overnight urine sample on the morning of the second day, melamine levels in the rest of urine samples among the study children were all detectable. The median melamine levels of 1-spot overnight urine samples on the first and second day mornings were 0.93 and 1.73 μg/mmol of creatinine respectively. We found that melamine concentrations of 1-spot overnight urine samples on the second day morning were highly correlated with the previous 8- and 24-h total melamine excretions in urine (r=0.936, p<0.001, n=21 and r=0.616, p<0.001, n=21 respectively). Good correlation of 1-spot overnight urine sample on the first and second day mornings was also found (r=0.619, p=0.003, n=21). In contrast, there were no significant correlations of 24-h total urinary melamine and 24-h total urinary microalbumin and NAG excretions (r=-0.221, p=0.319, n=22 and r=0.084, p=0.710, n=22)., Conclusion: Melamine levels in 1-spot overnight urine sample can predict the previous 8- and 24-h total melamine excretions in urine. Since melamine exposure levels in these school children were relatively low, its association with clinical biomarkers of early renal injury was not found. A future study is necessary to increase the sample size and to find the more sensitive preclinical biomarkers of renal injury to link with low melamine exposure in children in the community., (Copyright © 2012 Elsevier B.V. All rights reserved.)

A simple, sensitive and reproducible isocratic reversed-phase (C(18) ) high-performance liquid chromatography (HPLC) method was developed to determine 7-O-succinyl macrolactin A (SMA) in rat plasma and urine samples using UV detector set at 230 nm. Lamotrigine was used as internal standards (IS) to ensure the precision and accuracy of the method. The retention times of SMA and IS for the plasma sample were 9.2 and 4.4 min, respectively, and those for the urine samples were 7.9 and 4.3 min, respectively. The intra- and inter-day variations of the analytical responses, expressed in terms of relative standard deviation, were less than 14.9%. The accuracy, in terms of average analytical recovery, ranged from 90.4 to 119%. The lower limits of quantification of SMA in rat plasma and urine samples were 0.02 and 0.1 µg/mL, respectively. This method is applicable for the pharmacokinetic studies of SMA in rats., (Copyright © 2012 John Wiley & Sons, Ltd.)

Melamine poisoning has become widely publicized after a recent occurrence of renal injury in infants and children exposed to melamine-tainted milk in China. This renal damage is believed to result from kidney stones formed from melamine and uric acid or from melamine and its cocrystallizing chemical derivative, cyanuric acid. However, the composition of the stones and the mechanism by which the stones are formed in the renal tubules are unknown. We report that cyanuric acid can be produced in the gut by microbial transformation of melamine and serves as an integral component of the kidney stones responsible for melamine-induced renal toxicity in rats. Melamine-induced toxicity in rats was attenuated and melamine excretion increased after antibiotic suppression of gut microbial activity [corrected]. We further demonstrated that melamine is converted to cyanuric acid in vitro by bacteria cultured from normal rat feces; Klebsiella was subsequently identified in fecal samples by 16S ribosomal DNA sequencing. In culture, Klebsiella terrigena was shown to convert melamine to cyanuric acid directly. Rats colonized by K. terrigena showed exacerbated melamine-induced nephrotoxicity. Cyanuric acid was detected in the kidneys of rats administered melamine alone, and the concentration after Klebsiella colonization was increased. These findings suggest that the observed toxicity of melamine may be conditional on the exact composition and metabolic activities of the gut microbiota.

Effects of the dosing matrix and timing on the onset of renal crystal formation were evaluated in male and non-pregnant female rats (Fisher 344) exposed to both melamine (MEL) and cyanuric acid (CYA) for 28 days. Rats were fed ground feed containing 60 ppm MEL and 60 ppm CYA, (5 mg/kg bw/day equivalent), or exposed via oral gavage to carboxymethylcellulose containing 5 mg/kg bw MEL followed by 5 mg/kg bw CYA either consecutively (<1 min apart) or delayed 45 min after MEL. Staggered gavage exposure to MEL/CYA caused extensive renal crystal formation as compared to when the two compounds were administered consecutively or in feed. Treatment related effects included reduced weight gain, feed consumption, and testicular weight and increased kidney weight, water consumption and urine output. Animals from the staggered MEL/CYA gavage exposure group became ill and were removed after 9 days of exposure. Approximately 1 week after the initiation of exposure microscopic urinalysis revealed MEL/CYA crystals in both groups of gavaged animals but not in the MEL/CYA feed treatment groups. Urinary crystals were smaller (10 μm) in animals consecutively gavaged. In contrast the urinary crystals were larger (20-40 μm) and frequently clumped in the animals in the staggered gavage group., (Published by Elsevier Ltd.)

Background: The link between melamine-contaminated daily foodstuffs and urolithiasis formation has drawn an international concern. However, detection of melamine levels in urine may not completely represent external melamine exposure. Thus, finding an additional analytical method for the study of environmental melamine exposure and its adverse effect in humans is crucial., Methods: Eleven adult patients diagnosed with uric acid urolithiasis were retrospectively analyzed. Melamine levels in their overnight one-spot urine samples were measured by a triple quadrupole liquid chromatography tandem mass spectrometry (LC-MS/MS). The compositions of stone samples were analyzed by the Fourier transform infrared (FTIR) spectrophotometer and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS)., Results: Seven (63.6%) out of 11 patients had detectable melamine levels in their urine specimens (method of detection limit: 0.8 ng/ml). Three patients (27.3%) were highly suspected of having melamine-containing urolithiasis in FTIR spectra. In one of those three cases who still had available stored stone specimens, MALDI-TOF MS further confirmed melamine components in this male patient's stone specimens. In contrast, his urinary melamine level was below the detection limit by LC-MS/MS., Conclusions: Direct analysis of melamine in the composition of urolithiasis by MALDI-TOF MS can be an additional analytical method to evaluate for external melamine exposure., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Terbuthylazine (TBA) is a herbicide widely used for weed control in corn crop. In mammals it is completely metabolized and excreted in urine, mostly as desetilterbutilazina (DET). This work aims to evaluate the use of urine and hair as matrices for monitoring short- and medium-term exposure to TBA. Levels of TBA and DET have been evaluated in hair and urine samples of 12 exposed farmers, 14 rural residents, 17 urban residents. In hair TBA was quantified in all samples of farmers and rural residents, but not of urban residents. In urine DET was detected in post-application samples of farmers but not in rural and urban residents. These results suggest that TBA in hair can be used as an index of cumulative exposure to TBA, while DET in the urine can be used as an index of short-term exposure in farmers.

A novel flow-injection chemiluminescence method for the determination of melamine in urine and plasma was developed. It was found that melamine can remarkably enhance chemiluminescence emission from the luminol-K(3) Fe(CN)(6) system in an alkaline medium. Under the optimum conditions, chemiluminescence intensity had a good linear relationship with the concentration of melamine in the range 9.0 × 10(-9) -7.0 × 10(-6) g/mL, with a correlation coefficient of 0.9992. The detection limit (3σ) was 3.5 ng/mL. The method has been applied to determine the concentration of melamine in samples using liquid-liquid extraction. Average recoveries of melamine were 102.6% in urine samples and 95.1% in plasma samples. The method provided a reproducible and stable approach for the sensitive detection of melamine in urine and plasma samples., (Copyright © 2011 John Wiley & Sons, Ltd.)