Multiple Urine Samples Research Articles

Medications as a potential source of exposure to phthalates among women of childbearing age

ObjectiveTo evaluate the association between the use of medications potentially containing phthalates and urinary concentrations of specific phthalate metabolites around conception. MethodsWomen enrolled in the Environment and Reproductive Health project from 2006 to 2009 completed questionnaires about the use of medications and provided multiple urine samples before and after conception. We compared the mean urinary concentration of phthalate metabolites between users of phthalate containing medications and a matched unexposed control group. ResultsOne woman used Asacol® (mesalamine), which utilizes dibutyl phthalate (DBP) as a delayed release coating material, and had a mean urinary concentration of the main DBP metabolite 200 times higher than the controls (8176μg/L vs. 37.5μg/L). The three users of stool softeners had a higher concentration of the main diethyl phthalate (DEP) metabolite (8636μg/L vs. 714.2μg/L). Neither the three additional Prilosec® (omeprazole) users nor one cyclobenzaprine user had higher urinary concentration than controls. ConclusionSelected medications may be important sources of DBP and DEP exposures around conception.

Safety and efficacy of praziquantel syrup (Epiquantel®) against Schistosoma haematobium and Schistosoma mansoni in preschool-aged children in Niger

Given the characteristic age-prevalence curve of Schistosoma infection, preventive chemotherapy with praziquantel is primarily targeted at school-aged children, whilst, in highly endemic areas, other high-risk groups might be included for regular treatment. Nevertheless, schistosomiasis can affect children well before they reach school-age, but this population group is usually excluded from preventive chemotherapy. We assessed the safety and efficacy of praziquantel syrup (Epiquantel®) in preschool-aged children in three villages of Niger. Children aged ≤72 months provided multiple urine and stool samples that were microscopically examined using standard protocols. Schistosoma-positive children were treated with praziquantel syrup at a dose of 40mg/kg after a meal of millet porridge. Children remained under medical supervision for 4h and adverse events were recorded. Additionally, a questionnaire was administrated to the mothers/guardians 24h post-treatment for further probing of adverse events. Treatment efficacy was evaluated 3 and 6 weeks post-treatment using multiple stool and urine samples. A third of the 243 treated children reported adverse events within 4h, whilst a further 6.2% reported adverse events upon probing 24h post-treatment. Abdominal pain, bloody diarrhoea and sleepiness were the most common adverse events, but these were transient and self-limiting. Praziquantel syrup showed moderate-to-high efficacy against Schistosoma haematobium with egg reduction rates of 69.4% and 71.2% 3 and 6 weeks post-treatment and cure rates of 85.7% (95% confidence interval (CI) 79.7–90.5%) and 94.9% (95% CI 90.5–97.6%), respectively. Considerably lower cure and egg reduction rates were observed against Schistosoma mansoni (e.g. cure rate at 6-week post-treatment follow-up was only 50.6% (95% CI 39.9–61.2%). Concluding, praziquantel syrup is well tolerated in preschool-aged children with moderate-to-high efficacy against S. haematobium, but considerably lower efficacy against S. mansoni in Niger. A larger study is warranted to investigate the observed differences in species-specific susceptibilities and to assess operational issues and community-effectiveness.

Functionalized graphene oxide for clinical glucose biosensing in urine and serum samples

A novel clinical glucose biosensor fabricated using functionalized metalloid-polymer (silver-silica coated with polyethylene glycol) hybrid nanoparticles on the surface of a graphene oxide nanosheet is reported. The cyclic voltammetric response of glucose oxidase modification on the surface of a functionalized graphene oxide electrode showed a surface-confined reaction and an effective redox potential near zero volts, with a wide linearity of 0.1–20 mM and a sensitivity of 7.66 μA mM−1 cm−2. The functionalized graphene oxide electrode showed a better electrocatalytic response toward oxidation of H2O2 and reduction of oxygen. The practical applicability of the functionalized graphene oxide electrode was demonstrated by measuring the peak current against multiple urine and serum samples from diabetic patients. This new hybrid nanoarchitecture combining a three-dimensional metalloid-polymer hybrid and two-dimensional graphene oxide provided a thin solid laminate on the electrode surface. The easy fabrication process and retention of bioactive immobilized enzymes on the functionalized graphene oxide electrode could potentially be extended to detection of other biomolecules, and have broad applications in electrochemical biosensing.

Accuracy of Urine Circulating Cathodic Antigen (CCA) Test for Schistosoma mansoni Diagnosis in Different Settings of Côte d'Ivoire

BackgroundPromising results have been reported for a urine circulating cathodic antigen (CCA) test for the diagnosis of Schistosoma mansoni. We assessed the accuracy of a commercially available CCA cassette test (designated CCA-A) and an experimental formulation (CCA-B) for S. mansoni diagnosis.MethodologyWe conducted a cross-sectional survey in three settings of Côte d'Ivoire: settings A and B are endemic for S. mansoni, whereas S. haematobium co-exists in setting C. Overall, 446 children, aged 8–12 years, submitted multiple stool and urine samples. For S. mansoni diagnosis, stool samples were examined with triplicate Kato-Katz, whereas urine samples were tested with CCA-A. The first stool and urine samples were additionally subjected to an ether-concentration technique and CCA-B, respectively. Urine samples were examined for S. haematobium using a filtration method, and for microhematuria using Hemastix dipsticks.Principal FindingsConsidering nine Kato-Katz as diagnostic ‘gold’ standard, the prevalence of S. mansoni in setting A, B and C was 32.9%, 53.1% and 91.8%, respectively. The sensitivity of triplicate Kato-Katz from the first stool and a single CCA-A test was 47.9% and 56.3% (setting A), 73.9% and 69.6% (setting B), and 94.2% and 89.6% (setting C). The respective sensitivity of a single CCA-B was 10.4%, 29.9% and 75.0%. The ether-concentration technique showed a low sensitivity for S. mansoni diagnosis (8.3–41.0%). The specificity of CCA-A was moderate (76.9–84.2%); CCA-B was high (96.7–100%). The likelihood of a CCA-A color reaction increased with higher S. mansoni fecal egg counts (odds ratio: 1.07, p<0.001). A concurrent S. haematobium infection or the presence of microhematuria did not influence the CCA-A test results for S. mansoni diagnosis.Conclusion/SignificanceCCA-A showed similar sensitivity than triplicate Kato-Katz for S. mansoni diagnosis with no cross-reactivity to S. haematobium and microhematuria. The low sensitivity of CCA-B in our study area precludes its use for S. mansoni diagnosis.

Evaluation of urinary ribonucleoside profiling for clinical biomarker discovery using constant neutral loss scanning liquid chromatography/tandem mass spectrometry

The patterns and levels of urinary excreted ribonucleosides which reflect RNA turnover and metabolism in humans offer the potential for early detection of disease and monitoring of therapeutic intervention. A liquid chromatography/tandem mass spectrometry (LC/MS/MS) method employing constant neutral loss (CNL) scanning for the loss of the ribose moiety (132 u) was used to detect ribonucleosides in human urine and to evaluate this analytical platform for biomarker research in clinical trials. Ribonucleosides were stable and not influenced by the time spent at room temperature prior to freezing or long-term storage at -80 °C. Matrix effects caused variation in the mass spectrometer response which was dependent on the concentration of the analysed urine sample. For the use of urinary ribonucleoside profiling in clinical biomarker studies, adjustment of the urine samples to a common concentration prior to sample preparation is therefore advocated. Changes in the mass spectrometer response should be accounted for by the use of an internal standard added after sample preparation. Diurnal variation exceeded inter-day variation of an individual's ribonucleoside profile, but inter-person differences were predominant and allowed the separation of individuals against each other in a multivariate space. Due to considerable diurnal variation the use of spot urine samples would introduce unnecessary variation and should be replaced by the collection of multiple spot urine samples across the day, where possible. Should such a protocol not be feasible, biological intra-day and inter-day variation must be considered and accounted for in the data interpretation.

The Pharmacokinetics of Methanol in the Presence of Ethanol

Methanol is a toxic alcohol that can cause significant morbidity and mortality in overdose, while ethanol is a readily available and effective antidote. Little is known about the pharmacokinetics of methanol in the presence of ethanol and vice versa. This paper explores the influence of methanol and ethanol on the pharmacokinetics of each other along with the effect of continuous venovenous haemodiafiltration (CVVHD) on alcohol removal. Multiple plasma, urine and dialysate samples were collected from a 42-year-old male who ingested 166 g of methanol. Methanol and ethanol concentrations in both plasma and urine were assayed and the concentration-time data were modelled using nonlinear mixed-effects modelling software NONMEM® VI. Simulations were performed using the final model parameters in MATLAB® software where a variety of initial doses and ethanol infusions were assessed. The final model included a competitive metabolic interaction between methanol and ethanol as well as first-order elimination due to renal, CVVHD and an additional non-renal non-CVVHD mechanism. Simulations from the model show a loading dose of 28.4 g/70 kg of ethanol results in a target plasma concentration of 1 g/L. Due to the competitive interaction between methanol and ethanol, higher amounts of methanol require lower maintenance doses of ethanol but for longer. CVVHD was shown to increase the dose rate of ethanol required but to decrease the duration of the maintenance phase. A detailed understanding of the pharmacokinetics of methanol and ethanol in the presence of each other is required to accurately determine the doses of ethanol required to treat different methanol poisonings.

Exposure Assessment of the Developing Fetus and Newborn Infants: Methods to Measure Perchlorate and Related Anions in Maternal and Fetal Matrices

S-30B9-3 Background/Aims: Perchlorate is a commonly occurring environmental toxicant that may impair iodide transport, and thus compromise development of the fetus and neonate. Therefore, we developed analytical methods for quantifying perchlorate and toxicologically related anions (iodide, nitrate, thiocyanate) in physiological fluids relevant to fetal and neonatal exposure. Methods: We used ion chromatography coupled with electrospray ionization tandem mass spectrometry to accurately and precisely quantify background levels of perchlorate and related anions in urine and serum from pregnant women; amniotic fluid from the fetus; and cord blood, dried blood spots, and diaper press urine from newborns. Additionally, we validated methods for quantifying perchlorate and related anions in breast milk and infant formula so that perchlorate intake could also be calculated. We found that sample collection materials (eg, diapers and blood spot paper) are potential sources of perchlorate contamination. Results: Perchlorate was commonly found in maternal, fetal, and newborn matrices. Maternal urinary perchlorate levels were positively correlated with perchlorate levels in amniotic fluid (r = 0.57). Maternal serum perchlorate was generally higher than cord serum perchlorate (median ratio 2.4:1 for paired samples); conversely, iodide levels were typically higher in fetal fluids compared to maternal fluids. Perchlorate exposure doses were subsequently estimated for 91 infants based on multiple urine samples collected over the first year of life. The median estimated exposure dose was 0.160 μg/kg/d, with 9% of the estimated doses exceeding the US EPA reference dose of 0.7 μg/kg/d, and breast-fed infants having greater perchlorate exposure than formula-fed infants. Conclusion: Maternal urine perchlorate is an effective surrogate measure of fetal perchlorate exposure. Perchlorate does not appear to disproportionately accumulate in the fetal compartment; however, infants likely have higher perchlorate exposure doses than adults (medians of 0.160 and 0.064 μg/kg/d, respectively).

Variability over 1 Week in the Urinary Concentrations of Metabolites of Diethyl Phthalate and Di(2-Ethylhexyl) Phthalate among Eight Adults: An Observational Study

BackgroundPhthalates are metabolized and eliminated in urine within hours after exposure. Several reports suggest that concentrations of phthalate metabolites in a spot urine sample can provide a reliable estimation of exposure to phthalates for up to several months.ObjectivesWe examined inter- and intraperson and inter- and intraday variability in the concentrations of monoethyl phthalate (MEP), the major metabolite of diethyl phthalate, commonly used in personal care products, and mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), a metabolite of di(2-ethylhexyl) phthalate (DEHP), a polyvinyl chloride plasticizer of which diet is the principal exposure source, among eight adults who collected all urine voids (average, 7.6 samples/person/day) for 1 week.MethodsWe analyzed the urine samples using online solid-phase extraction coupled to isotope dilution–high-performance liquid chromatography–tandem mass spectrometry.ResultsRegardless of the type of void (spot, first morning, 24-hr collection), for MEP, interperson variability in concentrations accounted for > 75% of the total variance. By contrast, for MEHHP, within-person variability was the main contributor (69–83%) of the total variance. Furthermore, we observed considerable intraday variability in the concentrations of spot samples for MEHHP (51%) and MEP (21%).ConclusionsMEP and MEHHP urinary concentrations varied considerably during 1 week, but the main contributors to the total variance differed (interday variability, MEHHP; interperson variability, MEP) regardless of the sampling strategy (spot, first morning, 24-hr collection). The nature of the exposure (diet vs. other lifestyle factors) and timing of urine sampling to evaluate exposure to phthalates should be considered. For DEHP and phthalates to which people are mostly exposed through diet, collecting 24-hr voids for only 1 day may not be advantageous compared with multiple spot collections. When collecting multiple spot urine samples, changing the time of collection may provide the most complete approach to assess exposure to diverse phthalates.

The applicability of urinary creatinine as a method of specimen normalization in the cystic fibrosis population

Background Urine specimens are commonly used in biomarker research. Urinary creatinine (UCr) is often used to adjust for urine analyte concentration. We aim to explore the applicability of UCr as a normalization method in a cystic fibrosis (CF) population during hospitalization. Methods Multiple spot urine samples were collected from CF patients hospitalized for a pulmonary exacerbation. Single spot specimens were obtained from asthmatics and healthy children for comparison. The assumptions and implications from the use of UCr as a normalization factor for urinary desmosine measurements were investigated. Results UCr differed significantly across disease groups and decreased significantly over time in the CF population. Differing results were obtained when contrasting normalization by UCr with specific gravity. Conclusions UCr levels are not completely attributable to simply variations in urine concentration. Analysis of urinary biomarker measurements should be initiated with an understanding of the relative effects of the normalization process on the results.

In-depth investigation of the molecular pathogenesis of bladder cancer in a unique 26-year old patient with extensive multifocal disease: a case report

BackgroundThe molecular characteristics and the clinical disease course of bladder cancer (BC) in young patients remain largely unresolved. All patients are monitored according to an intensive surveillance protocol and we aim to gain more insight into the molecular pathways of bladder tumors in young patients that could ultimately contribute to patient stratification, improve patient quality of life and reduce associated costs. We also determined whether a biomarker-based surveillance could be feasible.Case PresentationWe report a unique case of a 26-year-old Caucasian male with recurrent non-muscle invasive bladder tumors occurring at a high frequency and analyzed multiple tumors (maximal pTaG2) and urine samples of this patient. Analysis included FGFR3 mutation detection, FGFR3 and TP53 immunohistochemistry, mircosatellite analysis of markers on chromosomes 8, 9, 10, 11 and 17 and a genome wide single nucleotide polymorphism-array (SNP). All analyzed tumors contained a mutation in FGFR3 and were associated with FGFR3 overexpression. None of the tumors showed overexpression of TP53. We found a deletion on chromosome 9 in the primary tumor and this was confirmed by the SNP-array that showed regions of loss on chromosome 9. Detection of all recurrences was possible by urinary FGFR3 mutation analysis.ConclusionsOur findings would suggest that the BC disease course is determined by not only a patient's age, but also by the molecular characteristics of a tumor. This young patient contained typical genetic changes found in tumors of older patients and implies a clinical disease course comparable to older patients. We demonstrate that FGFR3 mutation analysis on voided urine is a simple non-invasive method and could serve as a feasible follow-up approach for this young patient presenting with an FGFR3 mutant tumor.

Urinary Protein Profiles in a Rat Model for Diabetic Complications

Diabetes mellitus is estimated to affect approximately 24 million people in the United States and more than 150 million people worldwide. There are numerous end organ complications of diabetes, the onset of which can be delayed by early diagnosis and treatment. Although assays for diabetes are well founded, tests for its complications lack sufficient specificity and sensitivity to adequately guide these treatment options. In our study, we employed a streptozotocin-induced rat model of diabetes to determine changes in urinary protein profiles that occur during the initial response to the attendant hyperglycemia (e.g. the first two months) with the goal of developing a reliable and reproducible method of analyzing multiple urine samples as well as providing clues to early markers of disease progression. After filtration and buffer exchange, urinary proteins were digested with a specific protease, and the relative amounts of several thousand peptides were compared across rat urine samples representing various times after administration of drug or sham control. Extensive data analysis, including imputation of missing values and normalization of all data was followed by ANOVA analysis to discover peptides that were significantly changing as a function of time, treatment and interaction of the two variables. The data demonstrated significant differences in protein abundance in urine before observable pathophysiological changes occur in this animal model and as function of the measured variables. These included decreases in relative abundance of major urinary protein precursor and increases in pro-alpha collagen, the expression of which is known to be regulated by circulating levels of insulin and/or glucose. Peptides from these proteins represent potential biomarkers, which can be used to stage urogenital complications from diabetes. The expression changes of a pro-alpha 1 collagen peptide was also confirmed via selected reaction monitoring.

P.048 Comparative study in the quality control of viral diagnostic reagents storage temperatures in two laboratories in Abuja, Nigeria

Background: The majority of the human population is infected with two human polyomaviruses BK virus (BKV) and JC virus (JCV) during childhood. After initial infection both viruses persist within renal system. Reactivation of both viruses may be linked with immunodeficiency or immunosuppressive therapy. Objective: To evaluate the relationship between immunodeficiency and viruria, prevalence of BK and JC viruria over time was investigated in a cohort of HIV seropositive individuals at different stages of disease. The excretion in this group was compared with virus excretion in their HIV seronegative partners and in an unselected cohort of patients attending a Genito-Urinary Medicine (GUM) clinic. Study design: The excretion of BKV and JCV DNA in multiple urine samples from HIV-infected patients at different stages of disease and their HIV-negative partners, and in single samples from a cohort of patients at a GUM clinic was investigated. A microplate hybridisation method was developed to increase both the sensitivity and specificity of detection of the PCR product. The method was also applied to estimate the DNA copy numbers of BKV and JCV in urine samples. Results: Within the HIV group, the level of immunosuppression (CD4+ category) was not associated with JCV viruria. By contrast, there was a modest correlation between immunodeficiency as indicated by a decline in CD4+ count and BKV viruria. Shedding of both BKV and JCV DNA together in urine samples of HIV-infected patients was much higher than in control groups (P=0.02), indicating that HIV infection may associate with polyomavirus reactivation. The incidence of flu-like syndrome was much higher in HIV-infected asymptomatic individuals than acquired immunodeficiency syndrome (AIDS)-related complex (ARC)/AIDS patients. In general, the concentration of BKV DNA viruria (DNA copy number) was dependent to CD4+ counts (P=0.008) while concentration of JCV DNA was independent to CD4+ cell count (P=0.54). The prevalence of BKV and JCV DNA in patients who were infected with C. trachomatis was 9/50 (18%) and 11/50 (22%), respectively. BKV and JCV DNA was detected in 3/19 (15%) and 2/19 (10%) of patients who were infected with N. gonorrhoea. Results suggested that persons infected with C. trachomatis were more likely to show BKV and JCV viruria. Conclusion: These results confirm that shedding of BK and JC viruses in urine is not exclusively found in immunosupression, it may also occur in healthy individuals. The frequency of virus excretion is however, apparently increased in HIV-infected patients, although no firm statistical difference could be established. One of the interesting aspects of these findings was the relatively high incidence of BKV and JCV viruria in both control groups, i.e. HIV-negative partners of HIV-infected patients and patients attending a GUM clinic.

Food Frequency Questionnaires and Overnight Urines Are Valid Indicators of Daidzein and Genistein Intake in U.S. Women Relative to Multiple 24-h Urine Samples

Data regarding convenient, valid methods for measuring U.S. isoflavone intake are limited. We evaluated a soy food questionnaire (SFQ), the Willett food frequency questionnaire (FFQ), and overnight urine samples relative to excretion in 24-h urine samples. We also described intake among women in a high-risk program for breast or ovarian cancer. Between April 2002 and June 2003, 451 women aged 30 to 50 yr with a family history of breast or ovarian cancer completed the SFQ and FFQ. Of them, 27 provided four 24-h and overnight urine specimens. In these women, 24-h sample measures were correlated with SFQ estimates of daidzein (Spearman r = .48) and genistein (r = .54) intake, moderately correlated with the Willett FFQ (daidzein r = .38, genistein r = .33), and strongly correlated with overnight urine excretion (daidzein r = .84, genistein r = 0.93). Among all 451 SFQ respondents, mean (median) daidzein and genistein intakes were 2.8 (0.24) and 3.9 (0.30) mg/day. Primary sources of both were soymilk, soy nuts, and tofu. We conclude that targeted soy food questionnaires, comprehensive FFQs, and multiple overnight urines are all reasonable options for assessing isoflavone intake in epidemiologic studies.

Estimating dietary caffeine exposure and CYP1A2, NAT2 and XO enzyme function by urinary caffeine metabolite biomonitoring: a pilot study.

Epidemiologic studies almost exclusively use food frequency reporting for assessing caffeine consumption. Major dietary caffeine sources, such as coffee and tea, are difficult to standardize for caffeine content due to their inherent heterogeneity. In this pilot study the determination of urinary caffeine and 15 metabolites was explored as a means of assessing caffeine exposure. Measurements were also used to investigate the identification of CYP1A2, NAT2 and XO activity phenotypes using uncontrolled caffeine exposure. Multiple spot urine samples were collected from volunteers over a period of one week during which food diaries were maintained. Urinary caffeine and metabolites were quantified by normal‐phase HPLC with UV‐visible absorbance detection. Using this approach, 13 of 15 metabolites were chromatographically resolved. Significant (p ≥ 0.05) associations between caffeine consumption estimated from food diaries and urinary caffeine and 1,7‐dimethyluric acid levels were observed. Using metabolite ratios proposed in the scientific literature, CYP1A2, NAT2 and XO enzyme activity phenotypes could be determined for all subjects. Though intra‐week variation in these ratios was observed in all subjects, in most cases the values remained within a given phenotype category. These results are promising for the future development of caffeine exposure and enzyme activity biomonitoring protocols.

Hemoglobin and overt nephropathy complications in type 1 diabetes.

Anemia tends to be more severe and occur earlier in individuals with diabetic nephropathy. We thus examined whether hemoglobin (HGB) relates to end-stage renal disease (ESRD), coronary artery disease (CAD), and all cause mortality in type 1 diabetes (T1D) subjects with overt nephropathy (ON). We prospectively followed up 174 individuals with childhood-onset T1D and ON (albumin excretion rate >200 microg/min in multiple urine samples) from the Pittsburgh Epidemiology of Diabetes Complications Study cohort for 12 years. One hundred forty persons had ON at baseline, whereas another 34 were followed up from their incidence of ON as determined by biennial examinations. Baseline HGB inversely predicted ESRD (hazard ratio [HR] = 0.70, 0.61-0.80) and mortality (HR = 0.84, 0.72-0.98), but not CAD (HR = 0.91, 0.79-1.0). After adjustment for sex, diabetes duration, and other known risk factors, HGB remained significantly predictive of ESRD (HR = 0.72, 0.61-0.85), but not CAD (HR = 0.94, 0.80-1.10) or overall mortality (HR = 0.92, 0.77-1.10). However, in those who never progressed to ESRD, HGB was significantly predictive of mortality (HR = 0.59, 0.39-0.89). After including ESRD as a time-dependent, HGB was significantly predictive of overall mortality (HR = 0.75, 0.59-0.93). Gender-specific analyses, although limited by sample size, suggests similarity in the association between absolute HGB and ESRD in both genders, but differences for CAD and mortality. Our data suggest that in T1D with ON, a higher HGB level is associated not only with reduced risk of ESRD, but also of mortality, particularly in those who do not develop ESRD. HGB, even in the clinically normal range, is able to predict long-term complications in those with T1D and ON.

Measurement of cortisol in human Hair as a biomarker of systemic exposure

Current methods for measuring long-term endogenous production of cortisol can be challenging due to the need to take multiple urine, saliva or serum samples. Hair grows approximately 1 centimeter per month, and hair analysis accurately reflects exposure to drug abuse and environmental toxins. Here we describe a new assay for measurement of cortisol in hair, and determined a reference range for non-obese subjects. For measurement of cortisol in hair we modified an immunoassay originally developed for measuring cortisol in saliva. We compared hair samples obtained from various parts of the head, and assessed the effect of hair dying. We analyzed hair samples from non-obese subjects, in whom we also obtained urine, saliva and blood samples for cortisol measurements. The mean extraction recovery for hair cortisol standards of 100 ng/ml, 50 ng/ml and 2 ng/ml (n=6) was 87.9%, 88.9% and 87.4%, respectively. Hair cortisol levels were not affected by hair color or by dying hair samples after they were obtained. Cortisol levels were decreased in hair that was artificially colored before taking the sample. The coefficient of variation was high for cortisol levels in hair from different sections of the head (30.5 %), but was smaller when comparing between hair samples obtained from the vertex posterior (15.6%). The reference range for cortisol in hair was 17.7-153.2 pg/mg of hair (median 46.1 pg/mg). Hair cortisol levels correlated significantly with cortisol in 24-hour urine (r=0.33; P=0.041). The correlation of hair cortisol with 24-hour urine cortisol supports its relevance as biomarker for long-term exposure.

The variability of urinary cotinine levels in young children: Implications for measuring ETS exposure

This study examined the within-subject variability of urinary cotinine levels in young children (aged = 0.6-7.2 years) of smoking parents to determine the number of urine samples needed to provide accurate estimates of exposure to environmental tobacco smoke (ETS) for different time intervals. Secondary analyses were conducted of five independent studies (N = 376), in which multiple urinary cotinine measures had been collected over time periods up to 13 months. Over measurement periods of 4-15 days, the within-subject cotinine levels varied 3-5 times more than would be expected based on measurement error alone. Over 7-13 months, the within-subject variability was 10-20 times higher than would be expected based on the measurement error. Findings indicated that cotinine measures from single urine samples provided highly accurate estimates of only recent exposure (i.e., 2-3 days; rho = 0.99). To achieve similarly precise estimates of the mean cotinine level of an individual child over 4-15 days, up to nine urine samples may be necessary. Up to 12 urine samples may be required to achieve similarly precise estimates of ETS exposure over a 4- to 13-month period. Epidemiologic and clinical research on ETS exposure in children can benefit from multiple urine samples (a) to accurately measure average exposure at the level of the individual child, (b) to describe temporal patterns, (c) to detect incidences of peak exposure that would remain underrecognized if monitoring is limited to a single time point, and (d) to establish stable baseline levels and endpoints based on urine samples collected over clinically relevant time periods.

Diagnosing diabetic nephropathy by 1H NMR metabonomics of serum

The most severe complication of type 1 diabetes (T1DM) is diabetic nephropathy. It is associated with a high risk of cardiovascular complications and premature death and requires early detection to be efficiently treated. The clinical practice to diagnose diabetic nephropathy is also a non-optimal and tedious set up based on albumin excretion rate in multiple overnight or 24h urine samples. Conversely, in this study, these independent diagnostic data are used to provide a realistic testing case for applying (1)H NMR metabonomics of serum in a diagnostic fashion. 182 T1DM and 21 non-diabetic (non-T1DM) individuals were studied. The (1)H NMR of serum at 500 MHz was targeted at two molecular windows: lipoprotein lipids and low-molecular-weight metabolites. T1DM and non-T1DM individuals were exclusively separated by (1)H NMR. For diabetic nephropathy diagnosis in the T1DM patients, (1)H NMR data (and clinical biochemistry data) gave a sensitivity of 87.1% (83.9%) and a specificity of 87.7% (95.9%). The predictive values of positive and negative tests were 89.0% (95.5%) and 83.6% (79.2%), respectively. (1)H NMR metabonomics clearly distinguishes metabolic characteristics of T1DM and appears approximately as good a means to diagnose diabetic nephropathy from serum as an advanced set of biochemical variables.

Comparison of the Effects of Vitamins and/or Mineral Supplementation on Glomerular and Tubular Dysfunction in Type 2 Diabetes

We thank Rossing et al. (1) for their interest in our article (2) and agree that one measurement of albumin-to-creatinine ratio in morning spot urine at baseline and after 3 months is a potential limitation to our study. This limitation is described in detail in our discussion section. Although we did not obtain multiple spot urine samples or a 24-h urine collection to assess microalbuminuria, the random microalbumin-to-creatinine ratio has high reported sensitivity and specificity compared with …

Urinary biomarkers of 1,3-butadiene in environmental settings using liquid chromatography isotope dilution tandem mass spectrometry

Although, 1,3-butadiene is a known human carcinogen emitted from mobile sources, little is known about traffic-related human exposure to this toxicant. This pilot study was designed to characterize traffic-related environmental exposure to 1,3-butadiene and evaluate its urinary mercapturic acids as biomarkers of exposure in these settings. Personal air samples and multiple urine samples were collected on two separate occasions from three groups of individuals that differed by spatial proximity as well as intensity of traffic: (i) toll collectors, (ii) urban-weekday and (iii) suburban-weekend group. Air samples were analyzed using thermal desorption followed by GC/MS and urine samples were analyzed using isotope dilution liquid chromatography tandem mass spectrometry (ID-LC-MS/MS) for two mercapturic acids of 1,3-butadiene: monohydroxy-3-butenyl mercapturic acid (MHBMA) and 1,2-dihydroxybutyl mercapturic acid (DHBMA). Exposure differed between groups ( p < 0.05) with median values of 2.38, 1.62 and 0.88 μg/m 3 for toll collectors, the urban-weekday group and the suburban-weekend group, respectively. A refined ID-LC-MS/MS method enabled detection of MHBMA, previously detected only in occupational settings, with high frequency. MHBMA and DHBMA were detected in 95 and 100% of urine samples at levels (mean ± S.D.) of 9.7 ± 9.5, 6.0 ± 4.3 and 6.8 ± 2.6 ng/mL for MHBMA and 378 ± 196, 258 ± 133 and 306 ± 242 ng/mL for DHBMA for the three different groups, respectively. Mean biomarker levels were higher among the toll collectors compared to the other two groups, however, the differences were not statistically significant ( p > 0.05). This study is the first to evaluate 1,3-butadiene biomarkers for subtle differences in environmental exposures. However, additional research will be required to ascertain whether the lack of statistical association observed here is real or attributable to unexpectedly small differences in exposure between groups (<1 μg/m 3), non-specificity of the biomarker at low exposure, and/or small sample size.