Katarina Aleksa

Solid-phase microextraction for the detection of codeine, morphine and 6-monoacetylmorphine in human hair by gas chromatography-mass spectrometry.

INTRODUCTION Opiate hair analysis continues to prove difficult due to the scarcity of hair sample and low drug concentrations. For this reason, we developed a sensitive method utilizing headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS) for the detection of three principle opiates; codeine, morphine, and 6-acetylmorphine. METHODS Experimental conditions for HS-SPME and GC-MS were systematically optimized to produce the sensitive analytical method reported. Briefly, opiates were extracted from adult hair with methanol under agitation. The methanolic extract was then decanted into SPME autosampler vials, where deuterated standards of each of the 3 opiates were added at a concentration of 2 ng/mg. Samples were dried under N(2), derivatized, and subjected to HS-SPME coupled with GC/MS for analysis. RESULTS Preliminary datum for this study indicates detection limits for these 3 opiates are superior to that reported in the literature; an LOQ of 0.01 ng/mg for morphine and 6-acetylmorphine and 0.005 ng/mg for codeine. Linearity was evident between 0.01 ng/mg and 5 ng/mg for each opiate, with R(2) above 0.992. The robustness of the method was demonstrated to be acceptable as inter-day and intra-day precision fell below 15% for each opiate analyzed. CONCLUSION Compared with conventional methods, this method of detection for opiates is fast, simple, and accurate, with the sensitivity and specificity required in forensic and clinical toxicology.

An improved method for rapidly quantifying fatty acid ethyl esters in meconium suitable for prenatal alcohol screening.

Fatty acid ethyl esters (FAEEs) are nonoxidative metabolites of ethanol, and elevated levels of FAEE in meconium are a useful biomarker for heavy prenatal alcohol exposure. FAEE in meconium has been recommended as useful and cost-effective for universal screening for prenatal alcohol exposure. To support an efficient universal screening program, an analytical method to detect and quantify FAEE in meconium needs to be accurate, inexpensive, and rapid. The purpose of this study was to develop an analytical method that would satisfy these criteria and to validate this method using established laboratory guidelines. A method was developed and validated to detect and quantify four FAEEs (ethyl palmitate, ethyl linoleate, ethyl oleate, and ethyl stearate) from 0.5 g of meconium using d(5)-ethyl esters as internal standards. The sample undergoes liquid-liquid extraction with heptane:acetone, the heptane layer is isolated and evaporated, and then, the resulting residue undergoes headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry. The detection limits of the four FAEEs ranged from 0.020 to 0.042 nmol/g and are 6- to 25-fold lower than the individual FAEE threshold concentrations (0.5 nmol/g). This method also has good precision with the coefficient of variation ranging from 2.6 to 19.4% for concentrations of individual FAEE between 0.5 and 2.62 nmol/g meconium (n=4). Calculated concentrations of FAEE that underwent extraction from meconium were 100-101% of the expected concentration, demonstrating the accuracy of the method. The peak shape and retention time of each FAEE were unaffected by the presence of the matrix, and there is no carryover at clinically relevant concentrations. This method was also able to produce clean chromatograms from meconium samples that could not be quantified using a previous method because of high chromatographic background. This method provides an optimal approach to detecting and quantifying FAEE in meconium that could be used in a universal screening program for prenatal alcohol exposure.

Sex-Specific Effect of Insulin-Dependent Diabetes 4 on Regulation of Diabetes Pathogenesis in the Nonobese Diabetic Mouse

Many human autoimmune diseases are more frequent in females than males, and their clinical severity is affected by sex hormone levels. A strong female bias is also observed in the NOD mouse model of type I diabetes (T1D). In both NOD mice and humans, T1D displays complex polygenic inheritance and T cell-mediated autoimmune pathogenesis. The identities of many of the insulin-dependent diabetes (Idd) loci, their influence on specific stages of autoimmune pathogenesis, and sex-specific effects of Idd loci in the NOD model are not well understood. To address these questions, we analyzed cyclophosphamide-accelerated T1D (CY-T1D) that causes disease with high and similar frequencies in male and female NOD mice, but not in diabetes-resistant animals, including the nonobese diabetes-resistant (NOR) strain. In this study we show by genetic linkage analysis of (NOD × NOR) × NOD backcross mice that progression to severe islet inflammation after CY treatment was controlled by the Idd4 and Idd9 loci. Congenic strains on both the NOD and NOR backgrounds confirmed the roles of Idd4 and Idd9 in CY-T1D susceptibility and revealed the contribution of a third locus, Idd5. Importantly, we show that the three loci acted at distinct stages of islet inflammation and disease progression. Among these three loci, Idd4 alleles alone displayed striking sex-specific behavior in CY-accelerated disease. Additional studies will be required to address the question of whether a sex-specific effect of Idd4, observed in this study, is also present in the spontaneous model of the disease with striking female bias.

Detection of polybrominated biphenyl ethers (PBDEs) in pediatric hair as a tool for determining in utero exposure

INTRODUCTION Cryptorchidism, or undescended/maldescended testis, is the most common birth defect of male genitalia. Its prevalence has been increasing over the past few decades. This may be due to an increase in the prevalence of anti-androgenic chemicals such as polychlorinated biphenyls, organochloride pesticides, plasticizers and fungicides. A newer group of chemicals, brominated flame retardants (BFRs), are being implicated as endocrine-disrupting chemicals. These chemicals are used worldwide in polymers that are incorporated into a variety of consumer products (e.g., textile, computers and televisions, insulating foam, electrical equipment and kitchen appliances). In order to quantify BFRs we introduce the use of hair levels of polybrominated diphenyl esters (PBDEs) as biomarkers of systemic exposure. This approach will allow for the estimation of in utero BFR exposure, in the process of evaluating the potential link between the incidence of cryptorchidism in newborn males and level of exposure of the pregnant mother to environmentally relevant BFRs. For that end we have developed a GC/MS assay in which childrens hair is analyzed for the presence of polybrominated biphenyl ethers (PBDEs). METHODS In this pilot, 10-40mg of hair from 24 children (12 newborn and 12 from children 1 to 15 years) was extracted overnight at 40°C with 4N HCl and hexane (4:1). The samples were eluted from 2g NaSO(4):2g Florisil SPE columns with 8mL hexane. Dried samples are reconstituted with anhydrous isooctane and injected onto a GC/MS and analyzed for BDE-28, BDE-47, BDE-99, BDE-100, BDE-153, BDE-154, BDE-183 and BDE-209. RESULTS PBDEs were detected in all of the newborn and child hair. The ΣPBDE ranged from 0.038 to 1.01pg/mg newborn hair and from 0.208 to 2.695ng/mg child hair. The most abundant PBDE in newborn hair was BDE-153 while in child hair the variable PBDEs were BDE-47 and BDE-99. The highest molecular weight congener BDE-209 was detected in 10/24 pediatric hair samples. The LOQ is 0.0625pg/mg (BDE-209 0.625pg/mg) and the efficiency of extraction was between 70 and 90%. CONCLUSION This GC/MS method is sufficiently sensitive to detect the presence of all 8 PBDE congeners tested in as little as 10mg of pediatric hair. The results show that PBDEs are present in newborn hair, making this matrix useful in examining in utero exposure to PBDEs and linking it to cryptorchidism.

Transfer of dabigatran and dabigatran etexilate mesylate across the dually perfused human placenta.

OBJECTIVE: To assess the transplacental pharmacokinetics at term of the oral thrombin inhibitor, dabigatran, and its prodrug, dabigatran etexilate mesylate, to estimate fetal drug exposure. METHODS: Placentae were obtained with informed consent after cesarean delivery of healthy term pregnancies in Toronto, Ontario, Canada. The transplacental transfer of dabigatran and dabigatran etexilate mesylate was separately assessed using the ex vivo dual perfusion of an isolated human placental cotyledon. Dabigatran, at a concentration of 35 ng/mL, was added to the maternal circulation at the start of the experimental phase. Maternal and fetal samples were taken throughout the preexperimental (1 hour) and experimental (3 hours) phases for measurement of dabigatran and markers of placental viability. Separate placenta perfusions with dabigatran etexilate mesylate were conducted at an initial maternal concentration of 3.5 ng/mL. Dabigatran and dabigatran etexilate mesylate were measured using liquid chromatography–tandem mass spectrometry. RESULTS: There was slower transfer of dabigatran compared with antipyrine from the maternal-to-fetal circulation, because the median fetal-to-maternal concentration ratio was 0.33 (interquartile range 0.29–0.38) after 3 hours (n=3). The prodrug, dabigatran etexilate mesylate, had limited placental transfer as characterized by a fetal-to-maternal ratio of 0.17 (interquartile range 0.15–0.17) after 3 hours (n=3). Placental viability markers for all perfusions were within normal ranges. CONCLUSION: This report provides direct evidence of the transfer of dabigatran and its prodrug across the term human placenta from the mother to the fetus. From a clinical perspective, these data suggest that, pending further study, dabigatran should not be used for anticoagulation of pregnant women, because the drug may have an adverse effect on fetal blood coagulation.

Glyburide transport across the human placenta.

OBJECTIVE: To estimate the magnitude of transplacental transfer of glyburide in women with gestational diabetes mellitus (GDM). METHODS: A prospective, observational study was conducted on women with GDM on glyburide therapy. On delivery admission, the glyburide dose and time of last dose were recorded. Immediately postdelivery, maternal and umbilical venous blood samples were obtained and the concentrations of glyburide were determined by high-performance liquid chromatography–mass spectrometry with a limit of detection of 0.25 ng/mL. RESULTS: Nineteen patient dyads were analyzed. The mean total daily maternal glyburide dose was 6.6±6.3 mg per day and the mean time between last dose and sampling was 13.3±6.5 hours. The mean maternal serum glyburide level at birth was 15.4±20.8 ng/mL, whereas the mean umbilical glyburide level was 7.5±8.2 ng/mL, which showed a statistical correlation (r 2=0.72, P<.01). There were statistically significant relationships between total maternal glyburide dose (1.25–20 mg per day) and maternal glyburide levels (0.93–70.71 ng/mL; r 2=0.46, P⩽.01) and between total maternal glyburide dose and umbilical glyburide levels (0.95–32.41 ng/mL; r 2=0.43, P⩽.01) However, we observed wide variability in maternal and umbilical glyburide levels at both extremes of the total glyburide dose. Seventy-nine percent of cord samples (15/19) had glyburide levels less than 10 ng/mL (the limit of detection reported in earlier studies) and 37% (7/19) were higher than the corresponding maternal samples. CONCLUSION: Transplacental transfer of glyburide is highly variable among patients, corroborating ex vivo placental perfusion studies showing a transport-mediated glyburide efflux from the fetal to the maternal circulation. In most neonates (79%), glyburide levels were below 10 ng/mL. LEVEL OF EVIDENCE: III

Young age and the risk for ifosfamide-induced nephrotoxicity: a critical review of two opposing studies

Abstract. Ifosfamide has been in use as an effective antineoplastic agent for solid tumors in both children and adults since the late 1960s. Although some adverse effects (e.g. hemorrhagic cystitis) can be overcome by the co-administration of 2-mercaptoethanesulfonate (MESNA), others such as nephrotoxicity cannot. There is a consensus that factors such as the cumulative dose of ifosfamide and concomitant cisplatin administration may influence not only the incidence but also the severity of ifosfamide-induced renal toxicity. Several preliminary studies suggested young age as a risk factor for nephrotoxicity; however, there is little agreement on this. The reasons for this uncertainty may include sample size, study design, dose and differences in renal function assessment. In this review we examine the two largest cohort studies conducted in pediatric patients. One study suggests that ifosfamide-induced renal toxicity is age- related, whereas analysis of the other failed to show age as an important predictor for ifosfamide-induced renal toxicity. The studies differed in design, end-points of toxicity and concomitant drug therapy. Due to the effectiveness of ifosfamide as an antineoplastic agent, it is important that an understanding of the factors that predispose pediatric patients to ifosfamide-induced nephrotoxicity be obtained.

N‐acetylcysteine as a Novel Prophylactic Treatment for Ifosfamide‐Induced Nephrotoxicity in Children: Translational Pharmacokinetics

Ifosfamide (IFO), which is used in the treatment of pediatric solid tumors, causes high rates of nephrotoxicity. N‐acetylcysteine (NAC), an antidote for acetaminophen overdose, has been shown to prevent IFO‐induced renal cell death and nephrotoxicity in both LLCPK‐1 cells and a rat model. To facilitate the use of NAC in preventing IFO‐induced nephrotoxicity in children, the authors compared the systemic exposure to NAC in children treated for acetaminophen overdose to the systemic exposure of the therapeutically effective rat model. The mean systemic exposure in the rat model was 18.72 mM·h (range, 9.92–30.02 mM·h), compared to the mean systemic exposure found in treated children (14.48 mM·h; range, 6.22–32.96 mM·h). They also report 2 pediatric cases in which NAC‐attenuated acute renal failure associated with IFO when given concurrently with their chemotherapy treatment. Systemic exposure to NAC measured in 1 of these cases was comparable to that in the children treated for acetaminophen overdose. These results corroborate NACs potential to protect against IFO‐induced nephrotoxicity in children when used in its clinically approved dose schedule and supports a clinical trial in children.

Hair as a biomarker of systemic exposure to polybrominated diphenyl ethers.

The efficacy of using hair as a biomarker for exposure to polybrominated diphenyl ether (PBDE) flame retardants was assessed in humans and an animal model. Paired human hair and serum samples were obtained from adult men and women (n = 50). In parallel, hair, serum, liver, and fat were collected from adult male Sprague-Dawley rats exposed to increasing doses of the PBDE mixture found in house dust for 70 days via the diet. All samples were analyzed by GC-MS for eight common PBDEs: BDE-28, -47, -99, -100, -153, -154, -183, and -209. Paired human hair and serum samples had five congeners (BDE-28, -47, -99, -100, and -154) with significant individual correlations (0.345-0.566). In rat samples, BDE-28 and BDE-183 were frequently below the level of detection. Significant correlations were observed for BDE-47, -99, -100, -153, -154, and -209 in rat hair, serum, liver, and fat across doses, with r values ranging from 0.803 to 0.988; weaker correlations were observed between hair and other tissues when data from the lowest dose group or for BDE-209 were analyzed. Thus, human and rat hair PBDE measurements correlate strongly with those in alternative matrices, validating the use of hair as a noninvasive biomarker of long-term PBDE exposure.

The transfer of ethyl glucuronide across the dually perfused human placenta

INTRODUCTION Alcohol consumption during pregnancy can lead to Fetal Alcohol Spectrum Disorder (FASD), and because maternal self-reports are often unreliable, biomarkers of alcohol use are sometimes necessary to accurately determine fetal risk. Ethyl glucuronide (EtG), a direct metabolite of ethanol, has been detected in the meconium of infants born to mothers who consumed excessive alcohol during pregnancy. It is still unknown whether EtG detected in meconium originated from maternal hepatic glucuronidation of ethanol followed by subsequent placental transfer. Therefore, the objective of this study was to determine if EtG crosses the human placenta. METHODS The transfer of EtG was measured using the ex vivo dual perfusion of an isolated human placental lobule. EtG (1 μg/mL) was added to the maternal circulation and samples were taken throughout the 1 h pre-experimental and 3 h experimental phases for measurement of EtG and markers of placental viability. RESULTS After 3 h, the fetal-to-maternal ratio was 0.29 ± 0.02 and net maternal-to-fetal transfer was still occurring. Triplicate averages of EtG concentrations in perfused placental lobules ranged from 140 to 414 ng/g tissue. Placental validation markers were within normal ranges for all perfusions. DISCUSSION The data show that EtG crosses the human placenta and primarily represents maternal exposure to alcohol. CONCLUSIONS This information can help with the development of more thorough biomarker screens for alcohol use during pregnancy.