Metabolite Bis Research Articles

Association between exposure to organophosphate flame retardants and epidermal growth factor receptor expression in lung cancer patients.

Organophosphate flame retardants (OPFRs) are extensively distributed in our environment, prompting concerns about potential health hazards, including lung injuries resulting from OPFR exposure. The present study recruited 125 lung cancer patients, assessing their exposure to 10 OPFR compounds through urine samples. The final analysis comprised 108 participants after excluding those lacking epidermal growth factor receptor (EGFR) status and those with chronic kidney disease. Demographic and clinical characteristics, as well as urinary OPFR concentrations, were compared based on OPFR detection. Spearman correlation was conducted to explore the relationship between OPFR compounds, while logistic regression was used to identify OPFR compounds associated with EGFR mutation. The study revealed widespread OPFR exposure among lung cancer patients, with an overall detection frequency of 99.07%. Tris(2-butoxyethyl) phosphate (TBEP) exhibited a strong correlation to its metabolite bis(2-butoxyethyl) phosphate (r = 0.88, p < 0.01). Patients with TBEP in their urine had higher percentage of wild-type EGFR and the detection of TBEP was associated with a reduced likelihood of mutant EGFR expression. OPFR exposure was prevalent in lung cancer patients, with TBEP detection identified as a factor with lower EGFR mutation expression. This study contributes to the understanding of OPFR exposure in lung cancer patients and underscores the significance of TBEP in evaluating EGFR mutation in this population.

Isolation and characterization of an antibacterial compound Bis-(2-ethylhexyl) phthalate from the fungi Penicillium digitatum

Introduction and Aim: Penicillium is a fungal antibiotic derived from Penicillium notatum. In this study, we aimed to isolate the antibacterial compound Bis-(2-ethylhexyl) phthalate from the fungi Penicillium digitatum, as well as study its antibacterial activity against the the pathogens Escherichia coli,Group B Streptococcus agalactiae, and Staphylococcus aureus. Materials and Methods: The identification of Bis-(2-ethylhexyl) phthalate-containing secondary metabolite was achieved through bioassay-guided chemical analysis of the crude extract. The structure of the compound was identified from UV spectra, IR, and GC-MS spectral data. The antimicrobial activity of Bis-(2-ethylhexyl) phthalate, isolated from the fungus Penicillium digitatum, was determined using standard methods. Results: UV, IR, and GC-MS spectroscopy confirmed the crude extract of fungi Penicillium digitatum to contain the bioactive compounds 1,2-benzenedicarboxylic acid and bis(ethylhexyl) phthalate. The MIC value of the bioactive molecule was also determined to be 32 mg/ml. The P. digitatum ethyl acetate extract showed moderate antibacterial activity against the Gram-negative bacterial isolate Escherichia coli and high activity against the Gram positive pathogens Streptococcus agalactiae and Staphylococcus aureus. Conclusion: The fungi Penicillium digitatum produces the metabolite Bis-(2-ethylhexyl) phthalate, which exhibits antibacterial activity against Gram positive and Gram-negative pathogens and hence could be used in treating infections by these bacterial pathogens.

Comparative in Vivo Study on Quality Analysis on Bisacodyl of Different Brands

Abstract: Bisacodyl is an organic chemical belongs to the diphenylmethane family that is utilised as a laxative stimulant. To induce a bowel movement, it acts directly on the colon. It is commonly used to treat episodic and chronic constipation, as well as neurogenic bowel dysfunction, and as part of bowel preparation before medical procedures such as a colonoscopy. It has a dual prokinetic and secretory activity and must be converted in the stomach into the active metabolite bis-( p-hydroxyphenyl)-pyridyl2-methane (BHPM) to generate the intended laxative effect. Bisacodyl operates locally in the large bowel by directly improving motility, decreasing transit time, and raising stool water content. The tablets available on the market from various popular brands were chosen for the evaluation based on different quality control tests such as physical appearance, hardness, friability, disintegration time, weight variations, dissolution rate, and potency. The test will be implement of the certain kind of available product such as DULCOFLEX, BISOWEX, BISFLOW and BYLAX-5 which has active contain of 10mg/each respectively. This study is likely to be a point of appreciation in raising awareness among the people and prescriber communities about the importance of having a higher surplus of medicines by selecting the suitable medication from among some sorts of commercial brands which is available in market formulation.

A sensitive and quantitative immunochromatographic assay for simultaneous detection of three stimulant laxatives in slimming food

Bisacodyl, sodium picosulfate and their metabolite bis-(p-hydroxyphenyl)-pyridyl-2-methane (BHPM) are clinically used to treat constipation. In this study, with the rational hapten design, a broad-specific and highly sensitive monoclonal antibody (mAb) was obtained with half of inhibitory concentrations of 0.16, 0.18 and 0.65 ng/mL for bisacodyl, sodium picosulfate and BHPM, respectively. Based on this mAb, a rapid and sensitive lateral flow immunochromatographic assay toward bisacodyl, sodium picosulfate and BHPM in slimming foods was developed. This method can qualitatively and quantitatively screen three stimulant laxatives with cut-off values of 3–6 ng/mL by naked eye and quantitative detection limits of 0.14–0.41 ng/mL by reader. The acceptable recoveries of spiked samples (78.00 %–120.12 %) and consistent results with liquid chromatography with tandem mass spectrometry (LC-MS/MS) in real sample detection confirmed the accuracy of the method. The established method provides a technique for multiplex, sensitive, fast, and on-site detection of three stimulant laxatives in slimming food.

DETECTION OF GLIOTOXIN BUT NOT BIS(METHYL)GLIOTOXIN IN PLASMA FROM BIRDS WITH CONFIRMED AND PROBABLE ASPERGILLOSIS.

Aspergillosis remains a difficult disease to diagnose antemortem in many species, especially avian species. In the present study, banked plasma samples from various avian species were examined for gliotoxin (GT), which is a recognized key virulence factor produced during the replication of Aspergillus species hyphae and a secondary metabolite bis(methyl)gliotoxin (bmGT). Initially, liquid chromatography-tandem mass spectrometry methods for detecting GT and bmGT were validated in a controlled model using sera obtained from rats experimentally infected with Aspergillus fumigatus. The minimum detection level for both measurements was determined to be 3 ng/ml, and the assay was found to be accurate and reliable. As proof of concept, GT was detected in 85.7% (30/35) of the samples obtained from birds with confirmed aspergillosis and in 60.7% (17/28) of samples from birds with probable infection but only in one of those from clinically normal birds (1/119). None of the birds were positive for bmGT. Repeated measures from birds under treatment suggests results may have prognostic value. Further studies are needed to implement quantitative methods and to determine the utility of this test in surveillance screening in addition to its use as a diagnostic test in birds with suspected aspergillosis.

Plasma concentrations of tris(1-chloro-2-propyl) phosphate and a metabolite bis(2-chloroisopropyl) 1-carboxyethyl phosphate in Sprague-Dawley rats and B6C3F1/N mice from a chronic study of tris(chloropropyl) phosphate via feed

Tris(chloropropyl) phosphate (TCPP) is an organophosphorus flame retardant and plasticizer used in manufacturing and multiple consumer products. Commercial TCPP is a ubiquitous environmental contaminant and TCPP or its metabolites have been detected in human plasma and urine. In response to the demonstrated widespread human exposure and lack of toxicity data, the Division of the National Toxicology Program is investigating the chronic toxicity of TCPP following perinatal exposure in HSD:Sprague Dawley®SD® (HSD) rats (up to 20,000 ppm) and adult exposure in B6C3F1/N mice (females, up to 10,000 ppm; males up to 5000 ppm) to TCPP via feed. Systemic exposure and bioaccumulation were assessed by measuring plasma concentrations of tris(1-chloro-2-propyl)phosphate (TCIPP), the most abundant TCPP isomer. TCIPP concentrations in TCPP-exposed rats and mice ranged from 3.43 to 1180 ng/mL and increased with exposure concentration at all time points. No sex differences were observed in rats, but male mice had higher TCIPP concentrations than females. TCIPP did not bioaccumulate in rats or mice over the course of the study. Low TCIPP concentrations were seen in some control rats and mice that were attributed to background TCPP present during sample collection, preparation and/or analysis. Bis(2-chloroisopropyl) 1-carboxyethyl phosphate (BCPCP), a TCPP metabolite, was quantified in plasma from control and selected exposed animals. Results showed increases in BCPCP concentration that were proportional to exposure concentration in rats and mice at concentrations much higher than TCIPP, indicating that BCPCP might be a more suitable biomarker of TCPP exposure.

Targeting INMT and interrupting its methylation pathway for the treatment of castration resistant prostate cancer

BackgroundCastration-resistant prostate cancer (CRPC) is associated with a very poor prognosis, and the treatment of which remains a serious clinical challenge.MethodsRNA-seq, qPCR, western blot and immunohistochemistry were employed to identify and confirm the high expression of indolethylamine N-methyltransferase (INMT) in CRPC and the clinical relevance. Chip assay was used to identify Histone-Lysine N-Methyltransferase (SMYD3) as a major epigenetic regulator of INMT. LC-MS/MS were used to identify new substrates of INMT methylation in CRPC tissues. Gene knockdown/overexpression, MTT and mouse cancer models were used to examine the role of INMT as well as the anticancer efficacy of INMT inhibitor N,N-dimethyltryptamine (DMT), the SMYD3 inhibitor BCl-12, the selenium compounds methaneseleninic acid (MSA) and Se-(Methyl)selenocysteine hydrochloride (MSC), and the newly identified endogenous INMT substrate Bis(7)-tacrine.ResultsWe found that the expression of INMT was highly increased in CRPC and was correlated with poor prognosis of clinical prostate cancer (PCa). INMT promoted PCa castration resistance via detoxification of anticancer metabolites. Knockdown of INMT or treatment with INMT inhibitor N,N-dimethyltryptamine (DMT) significantly suppressed CRPC development. Histone-Lysine N-Methyltransferase SMYD3 was a major epigenetic regulator of INMT expression, treatment with SMYD3 inhibitor BCl-121 suppressed INMT expression and inhibits CRPC development. Importantly, INMT knockdown significantly increased the anticancer effect of the exogenous selenium compounds methaneseleninic acid (MSA) and Se-(Methyl)selenocysteine hydrochloride (MSC) as well as the endogenous metabolite Bis(7)-tacrine.ConclusionsOur study suggests that INMT drives PCa castration resistance through detoxification of anticancer metabolites, targeting INMT or its regulator SMYD3 or/and its methylation metabolites represents an effective therapeutic avenue for CRPC treatment.

Prenatal exposure to a mixture of organophosphate esters and intelligence among 8-year-old children of the HOME Study

Many environmental chemicals are being identified as suspected neurotoxicants based on the findings of both experimental and epidemiological studies. Organophosphate esters (OPEs), which are among the chemicals that have replaced neurotoxic polybrominated diphenyl ethers (PBDEs) after 2004, have also become an important public health topic as evidence regarding their potential for early-life neurotoxicity is growing. In 233 mother child pairs from Cincinnati, OH, we measured concentrations of the OPE metabolites bis(1,3-dichloro-2-propyl) phosphate (BDCIPP), bis-2-chloroethyl phosphate (BCEP), diphenyl phosphate (DPHP), and di-n-butyl phosphate (DNBP) in the urine of pregnant women at 16 and 26 weeks gestation and at delivery. At age 8 years, we assessed children’s cognition using the Wechsler Intelligence Scale for Children-IV. In models adjusted for maternal race, income, body mass index, and IQ, maternal urinary BCEP was associated with a modest increase in child full-scale IQ (ß: 0.81 per a ln-unit BCEP increase; 95 % CI: 0.00, 1.61) while other OPEs were not associated with changes in full-scale IQ or any IQ subscales. Maternal serum PBDE concentrations did not confound the relationships between urinary OPE metabolites and child IQ. Using Bayesian kernel machine regression, we did not find that concentrations of a mixture of OPE metabolites during gestation was associated with any child cognition measures. The results of this study are not consistent with other published work, and a larger sample size would be beneficial to explore potential associations more fully. Therefore, additional studies are necessary to continue studying prenatal OPE exposure and child neurodevelopment and behavior.

In-vessel composting of HMX and RDX contaminated sludge using microbes isolated from contaminated site

Current study was carried out with an objective to remediate highly contaminated sludge with HMX and RDX obtained from an explosive manufacturing facility in North India employing indigenous microbes, Arthrobacter subterraneus (isolate no. S2-TSB-17) and Bacillus sonorensis (isolate no. S8-TSB-4) which were isolated from the same contaminated site. In-vessel composting of the explosive contaminated sludge was performed in 12 different bioreactors using cow manure and garden waste as bulking agents. 78.5% degradation of HMX was observed in reactor no. 2 with Bacillus sonorensis having combination of 10% sludge, 70% cow manure and 20% garden waste on 80th day. Two secondary metabolites Bis(hydroxymethyl)nitramine and methylene dinitramine were identified while studying the degradation pathway. Similarly, degradation of 91.2% was observed for RDX in reactor no. 11 with consortia of Arthrobacter subterraneus and Bacillus sonorensis on 80th day. During the study, release of significant nitrate and nitrite ions were observed. It has already been established that RDX and HMX degradation leads to release of nitrite/nitrate ions. The highest nitrite (reactor no. 11) and nitrate (reactor no. 2) release observed were 24.02 ± 0.05 mg/kg and 30.65 ± 0.99 mg/kg on 50th and 70th day, respectively. Scanning electron microscopic studies confirmed the attachment and presence of microbes with solid surface and no deformation in structure was observed in the microbial cells due to contamination stress. Findings of the study concluded that in-vessel composting assisted with native bacterial species can be a potential technology for the treatment of explosive contaminated sludge at the contaminated sites.

Neurodevelopmental toxicity assessment of flame retardants using a human DNT in vitro testing battery

Due to their neurodevelopmental toxicity, flame retardants (FRs) like polybrominated diphenyl ethers are banned from the market and replaced by alternative FRs, like organophosphorus FRs, that have mostly unknown toxicological profiles. To study their neurodevelopmental toxicity, we evaluated the hazard of several FRs including phased-out polybrominated FRs and organophosphorus FRs: 2,2′,4,4′-tetrabromodiphenylether (BDE-47), 2,2′,4,4′,5-pentabromodiphenylether (BDE-99), tetrabromobisphenol A, triphenyl phosphate, tris(2-butoxyethyl) phosphate and its metabolite bis-(2-butoxyethyl) phosphate, isodecyl diphenyl phosphate, triphenyl isopropylated phosphate, tricresyl phosphate, tris(1,3-dichloro-2-propyl) phosphate, tert-butylphenyl diphenyl phosphate, 2-ethylhexyl diphenyl phosphate, tris(1-chloroisopropyl) phosphate, and tris(2-chloroethyl) phosphate. Therefore, we used a human cell–based developmental neurotoxicity (DNT) in vitro battery covering a large variety of neurodevelopmental endpoints. Potency according to the respective most sensitive benchmark concentration (BMC) across the battery ranked from <1 μM (5 FRs), 1<10 μM (7 FRs) to the >10 μM range (3 FRs). Evaluation of the data with the ToxPi tool revealed a distinct ranking (a) than with the BMC and (b) compared to the ToxCast data, suggesting that DNT hazard of these FRs is not well predicted by ToxCast assays. Extrapolating the DNT in vitro battery BMCs to human FR exposure via breast milk suggests low risk for individual compounds. However, it raises a potential concern for real-life mixture exposure, especially when different compounds converge through diverse modes-of-action on common endpoints, like oligodendrocyte differentiation in this study. This case study using FRs suggests that human cell–based DNT in vitro battery is a promising approach for neurodevelopmental hazard assessment and compound prioritization in risk assessment.Graphical abstract

Bisacodyl: A review of pharmacology and clinical evidence to guide use in clinical practice in patients with constipation.

BackgroundBisacodyl is a member of the diphenylmethane family and is considered to be a stimulant laxative. It has a dual prokinetic and secretory action and needs to be converted into the active metabolite bis‐(p‐hydroxyphenyl)‐pyridyl‐2‐methane (BHPM) in the gut to achieve the desired laxative effect. Bisacodyl acts locally in the large bowel by directly enhancing the motility, reducing transit time, and increasing the water content of the stool. A recent network meta‐analysis concluded that bisacodyl showed similar efficacy to prucalopride, lubiprostone, linaclotide, tegaserod, velusetrag, elobixibat, and sodium picosulfate for the primary endpoint of ≥3 complete spontaneous bowel movements (CSBM)/week and an increase of ≥1 CSBM/week over baseline. The meta‐analysis also found that bisacodyl may be superior to the other laxatives for the secondary endpoint of change from baseline in the number of spontaneous bowel movements per week in patients with chronic constipation. This observation stimulated the authors to review the available literature on bisacodyl, which has been available on the market since the 1950 s.PurposeThe aim of the current review was to provide an overview of the historic background, structure, function, and mechanism of action of bisacodyl. Additionally, we discuss the important features and studies for bisacodyl to understand its peculiar characteristics and guide its use in clinical practice, but also stimulate research on open questions.

Developmental circulatory failure caused by metabolites of organophosphorus flame retardants in zebrafish, Danio rerio.

Organophosphate triesters are used worldwide as additives in flame retardants and plasticizer as a replacement of polybrominated diphenyl ethers. Increasing evidence on human exposure to and environmental contamination with organophosphorus flame retardants (OPFRs) requires an adequate toxicity assessment for this class of chemicals. While developmental toxicity of several OPFRs has been reported, developmental effects of OPFR metabolites have still to be understood. The present study aimed at characterizing developmental effects of OPFR metabolites using zebrafish embryos (Danio rerio). Triphenyl phosphate (TPHP) and two of its metabolites, 3-hydroxylphenyl diphenyl phosphate and 4-hydroxylphenyl diphenyl phosphate, were most potent for inducing pericardial edema and reduction in blood flow in trunk vessels. Other TPHP metabolites, such as diphenyl phosphate and 4-hydroxylphenyl phenyl phosphate, showed no substantial increase in circulatory failure at concentrations up to 30μM. Tris (1,3-dichloro-2-propyl) phosphate showed circulatory failure at 30μM, but its metabolite bis(1,3-dichloro-2-propyl) phosphate did not. Neither tris(2-chloroethyl) phosphate nor its metabolite bis(2-chloroethyl) phosphate, induced circulatory failure. The circulatory failure appeared to be enhanced with the increase in the octanol-water partition coefficients of OPFRs and their metabolites, suggesting that developmental circulatory failure posed by these chemicals could be estimated by their bioaccumulative potential. The present study demonstrated developmental circulatory failure of hydroxylated TPHP metabolites, which was almost equipotent to TPHP. Diester OPFR metabolites showed no major developmental toxicity at the concentrations used in this study. The current results establish the foundation for further understanding the similarities and differences in the toxic mechanisms between OPFRs and their metabolites.

Determination of human metabolites of chlorinated phosphorous flame retardants in wastewater by N-tert-butyldimethylsilyl-N-methyltrifluoroacetamide-derivatization and gas chromatography-high resolution mass spectrometry

The analysis of wastewater for the determination of human biomarkers of exposure (human metabolites) is a non-intrusive, economic and complementary alternative to the analysis of urine in the monitoring of human exposure to chemicals of concern. This study provides the first gas chromatography-based method for the determination of three metabolites of chlorinated organophosphorous flame retardants (OPFRs: bis(2-chloroethyl) phosphate, bis(chloropropyl) phosphate and bis(1,3-dichloro-2-propyl) phosphate) in wastewater. A solid-phase extraction procedure based on the use of mixed-mode reversed-phase weak anion exchange sorbents was optimized including a fractionated elution of OPFRs and their metabolites. Analytes derivatization was investigated by comparing two silylating reagents, N-tert-butyldimethylsilyl-N-methyltrifluoroacetamide and N-methyl-N-(trimethylsilyl)trifluoroacetamide, the first one providing better results. Determination was performed by gas chromatography-high resolution mass spectrometry with a quadrupole-time-of-flight system (GC-QTOF) in order to improve selectivity. Furthermore, the use of GC-QTOF combined with the specific ion obtained from silylated metabolites (m/z 154.9924) can be exploited to screen for other phosphate ester metabolites. Under final conditions, the overall method performance was satisfactory, affording method detection limits ranging from 1.1 to 4.6 ng/L, percentages of recovery from 90% to 110%, and relative standard deviations below 13%. The analysis of composite raw wastewater samples collected over 24 h in the NW of Spain allowed to quantify, for the first time in this matrix, the metabolite bis(chloropropyl) phosphate at levels over 60 ng/L.

Hair analysis to discriminate voluntary doping vs inadvertent ingestion of the aromatase inhibitor letrozole.

Letrozole is an aromatase inhibitor, used to treat postmenopausal women with hormone receptor-positive or unknown advanced breast cancer. It is prohibited in sport because it is used together with androgen anabolizing steroids to avoid their adverse effects. In the case of an adverse analytical finding, it may be important to distinguish between repetitive use due to voluntary administration and occasional use, possibly due to involuntary intake. With the objective to identify the dose capable of producing a positive hair test, and to apply these results to the scenarios of inadvertent letrozole ingestion by an athlete, this study investigates the urinary excretion and incorporation into hair of single doses of letrozole. Seven subjects were recruited for an excretion study of letrozole and its metabolite bis(4-cyanophenyl) methanol (M1) in urine, after the consumption of 0.62mg, 1.25mg, and 2.5mg of letrozole, and to investigate the incorporation in hair after ingestion of 0.62mg and 2.5mg of letrozole. Urine and hair samples were also obtained from two women in chronic therapy. Urinary concentrations of letrozole and its metabolite M1 were lower in subjects administered once with 0.62mg, 1.25mg, or 2.5mg letrozole than in women in regular therapy with 2.5mg/day. In hair collected after a single dosage, concentrations of 16-60pg/mg were detected while in women in chronic therapy concentrations were higher than 160pg/mg all along the hair shaft. Hair analysis turned to be a promising possibility for the discrimination of letrozole repetitive use vs occasional/inadvertent administration.

Lomerizine, trimetazidine and bis-(4-fluorophenyl)-methylpiperazine in human urine after oral administration of lomerizine dihydrochloride: analysis by liquid chromatography-high resolution-tandem mass spectrometry.

In sports drugs testing, the differentiation between the abuse of the prohibited substance trimetazidine and that of the permitted drug lomerizine is required because trimetazidine is one of the metabolites of lomerizine. Therefore, it is important to identify a lomerizine-specific metabolite in urine that allows making the distinction. In this study, a simple dilute-and-shoot method employing liquid chromatography-high resolution-tandem mass spectrometry for the quantification of trimetazidine, lomerizine and the specific metabolite bis-(4-fluorophenyl)-methylpiperazine (M6) in urine was developed. An oral dose of 15mg was administered to 10 male volunteers, after which urine samples collected during the following 276hours were analyzed using the developed method, allowing for examination of the target analytes' excretion profile. The limit of detection of all target analytes was <0.02ng/mL. In all volunteers, the metabolite M6 was detected up to 276hours after administration. After more than 12hours, all volunteers were found to have higher concentrations of the metabolite M6 than of trimetazidine. The concentrations of trimetazidine, lomerizine, M6, and the M6/trimetazidine ratio in the final sample collected after 276hours were 0.2-0.9ng/mL, <0.05-0.1ng/mL, 14.1-38.3ng/mL, and 28.8-122.9, respectively. The urinary excretion of trimetazidine, unchanged lomerizine, and the metabolite M6 within the first 276hours was 0.64%, 0.006%, and 6.1%, respectively. Consequently, the absence of the metabolite M6 in doping control urine samples corroborates the conclusion that lomerizine is unlikely to be the source of trimetazidine. The results confirm that the M6 metabolite is the longest-lasting urinary metabolite of lomerizine currently known.

In ovo transformation of two emerging flame retardants in Japanese quail (Coturnix japonica)

Tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) and Dechlorane Plus (DP) are two chlorinated, alternative flame retardants that have been found in wild birds and bird eggs. Little is known about the fate and effect of these compounds in birds, especially during the vulnerable stages of embryonic development. To investigate the ability of birds to biotransform these compounds, an in ovo exposure experiment with Japanese quail eggs was performed. Quail eggs were injected in the yolk sac with 1000ng/g egg of TDCIPP (2.3 nmol/g ww), DP (1.5 nmol/g ww) or a mixture of both and were then incubated at 37.5°C for 17 days. To get a time-integrated understanding of the in ovo transformation of the compounds, one egg per treatment was removed from the incubator every day and analyzed for TDCIPP and its metabolite bis(1,3-dichloro-2-propyl) phosphate (BDCIPP) and/or for DP. By the end of the incubation period, TDCIPP was completely metabolized, while simultaneously BDCIPP was formed. The conversion of the parent compound into the metabolite did not occur proportionally and the concentration of BDCIPP showed a tendency to decrease when TDCIPP became depleted, both indicating that BDCIPP was further transformed into compounds not targeted for analysis. Further untargeted investigations did not show the presence of other metabolites, possibly due to the volatility of the metabolites. On the other hand, the DP concentration did not decrease during egg incubation. This study indicates that within the incubation period, avian embryos are able to biotransform TDCIPP, but not DP.

Abstract 2029: A high ratio of tamoxifen metabolite E to tamoxifen is associated with an increased risk of breast cancer recurrences in premenopausal women

Abstract Tamoxifen (Tam), a standard therapy for estrogen receptor (ER)-positive breast cancer, is excessively metabolized mainly by enzymes of the CYP450 family to anti-estrogenic and estrogenic compounds. Whereas in breast cancer cells the anti-estrogenic metabolites endoxifen and 4-hydroxy-Tam inhibit the ER, Tam bisphenol (Bis) and both isomers (E)- and (Z)- of metabolite E (Met E) show full estrogenic properties, with (E)-Met E being the most potent ER agonist. Contrary to known clinical effects of ER antagonists, the influence of Tam Bis, (E)-, and (Z)-Met E on treatment outcome is not thoroughly explored. Therefore we analyzed whether interindividual differences in plasma levels of estrogenic Tam metabolites interact with Tam therapy in vivo. Plasma concentrations of estrogenic metabolites Bis, (E)-, and (Z)-Met E and their metabolic ratios (MR) to Tam were quantified in 306 premenopausal breast cancer patients mainly of European origin who were treated with 20 mg/day of Tam (Eccles D, et al. BMC Cancer 2007; 7: 160) using recently published LC-MS/MS methods (Johänning et al. Anal Bioanal Chem 2015; Mürdter et al. Clin Pharmacol Ther 2011). The endpoints recurrence-free interval (RFI) and event-free survival (EFS) were analyzed in hormone-receptor positive patients (N = 296) by Kaplan-Meyer and multivariate Cox regression adjusted for age, nodal status, tumor size, grade and plasma concentrations of endoxifen (as MR of desmethyl-Tam to endoxifen). Plasma concentrations were as follows: Bis 13-832 pM (median 187 pM), (E)-Met E 15-1029 pM (median 213 pM), (Z)-Met E 128-2484 pM (median 889 pM), and Tam 47-1061 nM (median 360 nM). Patients with higher (E)-Met E to Tam ratios showed a higher risk of breast cancer recurrence when classified into quartiles: compared to patients of the lower quartile, patients had shorter RFI when they grouped to the interquartile (P = 0.037) and the upper quartile (P = 0.005). There was a trend of higher recurrence risk for patients belonging to the upper quartile compared to the interquartile (P = 0.063). These findings were confirmed in multivariate Cox analyses: patients belonging to the upper quartile had a significantly increased hazard ratio (HR) of 2.77 (95% confidence interval (CI) 1.34-5.71; P = 0.006) and patients belonging to the interquartile showed a trend for increased HR of 1.75 (CI = 0.88-3.46; P = 0.1). For EFS, a linearly increased HR was confirmed for patients with higher (E)-Met E to Tam ratios (HR = 1.44, CI = 1.06-1.97; P = 0.021). Bis, (Z)-Met E and their MRs to Tam showed no significantly altered risk of cancer recurrence or death. These findings suggest that higher formation rates of the most potent estrogenic Tam metabolite (E)-Met E influence Tam outcome in breast cancer patients and may be linked to therapeutic failure. Citation Format: Janina Johänning, Diana M. Eccles, Bryony Eccles, Michel Eichelbaum, Matthias Schwab, Hiltrud Brauch, Thomas Mürdter, Werner Schroth. A high ratio of tamoxifen metabolite E to tamoxifen is associated with an increased risk of breast cancer recurrences in premenopausal women. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2029.

Assessment of human hair as an indicator of exposure to organophosphate flame retardants. Case study on a Norwegian mother–child cohort

A major challenge of non-invasive human biomonitoring using hair is to assess whether it can be used as an indicator of exposure to Flame Retardants, such as Organophosphate Flame Retardants (PFRs), since the contribution of atmospheric deposition (air and/or dust) cannot be neglected. Therefore, the aim of this study was to evaluate the suitability of using human hair more thoroughly by comparison of (i) levels of PFRs in human hair (from 48 mothers and 54 children), with levels measured in dust and air in their respective households; and (ii) levels of selected PFRs in hair with the levels of corresponding PFR metabolites in matching urine samples collected simultaneously. Most PFRs (tri-n-butyl phosphate (TNBP), 2-ethyl-hexyldiphenyl phosphate (EHDPHP), tri-phenyl phosphate (TPHP), tri-iso-butyl phosphate (TIBP), and tris(2-butoxyethyl) phosphate (TBOEP)) were detected in all human hair samples, tris(2-ethylhexyl) phosphate (TEHP) and tris(1,3-dichloro-iso-propyl) phosphate (TDCIPP) in 93%, tri-cresyl-phosphate (TCP) in 69% and tris(2-chloroethyl) phosphate (TCEP) in 21% of the samples. Levels of individual PFRs ranged between <1 and 3744ng/g hair and were lower than in indoor dust from the participants' homes. Several statistically significant associations between PFR levels in human hair and PFR levels in house dust and/or air were found, e.g. Spearman correlation (rS=0.561, p<0.05) between TBOEP in children's hair and in indoor air. Also, associations were found between TDCIPP in hair and its metabolite bis(1,3-dichloro-iso-propyl) phosphate (BDCIPP) in urine; they were stronger for children (e.g. Pearson correlation rP=0.475; p=0.001) than for mothers (rP=0.395, p=0.01). Levels of diphenyl phosphate (DPHP) in mothers' and children's urine were slightly correlated (rS=0.409, p=0.008), suggesting similar sources of exposure. To the best of our knowledge, this is the first study with such design and our findings might help to understand human exposure to and body burdens of PFRs.

Developmental exposure to the organophosphorus flame retardant tris(1,3-dichloro-2-propyl) phosphate: Estrogenic activity, endocrine disruption and reproductive effects on zebrafish

Tris(1,3-dichloro-2-propyl) phosphate (TDCPP) is an organophosphate flame retardant that is detectable in the environment and biota, prompting concern over its risk to wildlife and human health. Our objective was to investigate whether long-term exposure to low concentrations of TDCPP can affect fish reproduction. Zebrafish embryos were exposed to low concentrations (0, 4, 20 and 100μg/L) of TDCPP from 2h post-fertilization until sexual maturation. Exposure to TDCPP significantly increased plasma estradiol and testosterone levels in females, but had no effect in males. TDCPP exposure also caused a significant reduction in fecundity as indicated by decreased egg production. Real-time PCR was performed to examine selected genes in the hypothalamic–pituitary–gonadal (HPG) axis and liver. Principle component analysis (PCA) showed that sex hormone levels and fecundity were related to the mRNA level of several genes in the HPG axis. Furthermore, hepatic vitellogenin (vtg1 and vtg3) expression was upregulated in both females and males, suggesting TDCPP has estrogenic activity. Histological examination revealed promotion of oocyte maturation in the females, but retardation of spermiation in males. Reduced egg quality (e.g., egg diameter) and increased malformation rates were observed in the F1 generation. Chemical analysis showed significant levels of TDCPP and its metabolite bis(1,3-dichloro-2-propyl) phosphate in the gonads of males and females. In conclusion, long-term exposure to low concentrations of TDCPP impairs fish reproduction.

Stimulant Laxatives for the Treatment of Chronic Constipation: Is it Time to Change the Paradigm?

Stimulant Laxatives for the Treatment of Chronic Constipation: Is it Time to Change the Paradigm?