A comparison of creatinine vs. specific gravity to correct for urinary dilution of cotinine

First clinical evidence that trimethylsulfonium can serve as a biomarker for the production of the signaling molecule hydrogen sulfide

BACKGROUND

Hydrogen sulfide (H2S) is established as the third gaseous signaling molecule and is known to be overproduced in down syndrome (DS) due to the extra copy of the CBS gene on chromosome 21, which has been suggested to contribute to the clinical manifestation of this condition. We recently discovered trimethylsulfonium (TMS) in human urine and highlighted its potential as a selective methylation metabolite of endogenously produced H2S, but the clinical utility of this novel metabolite has not been previously investigated. We hypothesize that the elevation of H2S production in DS would be reflected by an elevation in the methylation product TMS.

METHODS

To test this hypothesis, a case-control study was performed and the urinary levels of TMS were found to be higher in the DS group (geo. mean 4.5 nM, 95 % CI 2.4-3.9) than in the control (N) group (3.1 nM, 3.5-6.0), p-value 0.01, whereas the commonly used biomarker of hydrogen sulfide, thiosulfate, failed to reflect this alteration in H2S production (15 µM (N) vs. 13 µM (DS), p-value 0.24.

RESULTS

The observed association is in line with the proposed hypothesis and provides first clinical evidence of the utility of TMS as a novel and more sensitive biomarker for the endogenous production of the third gaseous signaling molecule than the conventionally used biomarker thiosulfate, which is heavily dependent on bacterial hydrogen sulfide production.

CONCLUSION

This work shows that TMS must be explored in clinical conditions where altered metabolism of hydrogen sulfide is implicated.

Method validation for (ultra)-trace element concentrations in urine for small sample volumes in large epidemiological studies: application to the population-based epidemiological multi-ethnic study of atherosclerosis (MESA)

Analysis of essential and non-essential trace elements in urine has emerged as a valuable tool for assessing occupational and environmental exposures, diagnosing nutritional status and guiding public health and health care intervention. Our study focused on the analysis of trace elements in urine samples from the Multi-Ethnic Study of Atherosclerosis (MESA), a precious resource for health research with limited sample volumes. Here we provide a comprehensive and sensitive method for the analysis of 18 elements using only 100 μL of urine. Method sensitivity, accuracy, and precision were assessed. The analysis by inductively coupled plasma mass spectrometry (ICP-MS) included the measurement of antimony (Sb), arsenic (As), barium (Ba), cadmium (Cd), cesium (Cs), cobalt (Co), copper (Cu), gadolinium (Gd), lead (Pb), manganese (Mn), molybdenum (Mo), nickel (Ni), selenium (Se), strontium (Sr), thallium (Tl), tungsten (W), uranium (U), and zinc (Zn). Further, we reported urinary trace element concentrations by covariates including gender, ethnicity/race, smoking and location. The results showed good accuracy and sensitivity of the ICP-MS method with the limit of detections rangings between 0.001 μg L-1 for U to 6.2 μg L-1 for Zn. Intra-day precision for MESA urine analysis varied between 1.4% for Mo and 26% for Mn (average 6.4% for all elements). The average inter-day precision for most elements was <8.5% except for Gd (20%), U (16%) and Mn (19%) due to very low urinary concentrations. Urinary mean concentrations of non-essential elements followed the order of Sr > As > Cs > Ni > Ba > Pb > Cd > Gd > Tl > W > U. The order of urinary mean concentrations for essential trace elements was Zn > Se > Mo > Cu > Co > Mn. Non-adjusted mean concentration of non-essential trace elements in urine from MESA participants follow the order Sr > As > Cs > Ni > Ba > Pb > Cd > Gd > Tl > W > U. The unadjusted urinary mean concentrations of essential trace elements decrease from Zn > Se > Mo > Cu > Co > Mn.

Influence of birth-related maternal and neonatal factors on the levels of energy metabolism mediators in infants born at 32 or fewer weeks of gestation

BACKGROUND

Energy metabolism mediators, which include the adipokines (leptin, adiponectin, ghrelin) and insulin-like growth factor 1 [IGF-1], are hormone-like proteins, produced and expressed in the placenta and fetal membranes, with properties featuring metabolic adaptation and inflammatory processes. Due to the complexity of the metabolic adaptation of preterm neonates during the transition to extrauterine life, it becomes essential to recognize the factors that influence the alteration of the adipokines and IGF-1 levels in the early postpartum stage.This study assessed the significance of maternal-fetal-neonatal factors in predicting the levels of leptin, adiponectin, ghrelin, and IGF-1 in preterm infants born at 32 or fewer weeks of gestation, during the early stage of postnatal adaptation.

METHODS

Energy metabolism mediator levels were measured in urine samples obtained from extremely (less than 28 weeks) and very (28-32 weeks) preterm infants, within 48 h after their birth, and before the initiation of enteral nutrition. The urine samples were analyzed using enzyme-linked immunosorbent assay (ELISA) kits. The collected data included all birth-related maternal and neonatal factors such as maternal age, race/ethnicity, hypertensive disorders of pregnancy, diabetes, gravidity, parity, type of pregnancy, mode of delivery, and antenatal use of corticosteroids, antibiotics, magnesium sulfate, Apgar scores at 1 and 5 min, gestational age, and birth weight. We investigated the correlation between the levels of the tested mediators, the significance of the differences in their average levels based on the dichotomized maternal and neonatal factors, and the effect of the selected factors, in multiple regression models. Data from the regression models constructed for leptin, adiponectin, ghrelin, and IGF-1 are presented as regression coefficient β with Standard Error (SE) of β, coefficient of determination (R2), and adjusted R2. Before including the factor in regression models, we tested for the multicollinearity effect. Two-sided P values <0.05 were considered statistically significant.

RESULTS

Among the 70 studied infants, 47.1% were male, 40.6% were white, 28.6% were extremely preterm, and 18.6% were born with a weight <750 grams. Except for a mild interplay between the adiponectin and IGF-1 levels, there was no correlation between the levels of the other studied mediators. Up to 20% variation in the tested energy metabolism mediator levels was dependent on some of the birth-related maternal and neonatal characteristics. For instance, leptin levels were reduced in association with male gender (-0.493 [0.190], p < 0.02) and increased in infants born to primigravids (0.562 [0.215], p < 0.02). Adiponectin levels were increased in infants born to nulliparous as compared to multiparous women (0.400 [0.171], p < 0.03). Ghrelin levels were reduced in males (-0.057 [0.026], p < 0.04). IGF-1 levels were increased in the urine of extremely preterm neonates (0.357 [0.111], p < 0.01) and preterm infants born with an Apgar less than three at 1 min (0. 340 [p < 0.153], p < 0.04).

CONCLUSIONS

Nearly one-fifth of the variation in the urinary levels of the adipokines (leptin, adiponectin, ghrelin) and IGF-1 during the early postnatal stage in infants born at 32 or fewer weeks of gestation was predicated on one or more of the maternal and neonatal factors such as the infant's sex, extreme preterm gestation, a low Apgar score at 1 min, or birth to nulliparous women or primigravida mothers. Further studies will be required to explain the role of energy metabolism mediators in the postnatal adaptation of preterm-born infants.

Sex-specific associations between urinary bisphenols concentrations during pregnancy and problematic child behaviors at age 2 years

Effects of prenatal bisphenol A (BPA) exposure on child behavior are mixed with some reports suggesting increased problematic behaviors in girls (e.g., aggression and emotional reactivity) and in boys (i.e., externalizing behaviors), while other reports suggest decreased problematic behaviors in girls. Little is known about the potential impact of pregnancy bisphenol S (BPS) exposure on child behavior. In a prospective cohort study (n = 68), five maternal spot urine samples collected across pregnancy were pooled and analyzed for BPA and BPS. Child behavior at 2 years was assessed using the Child Behavior Checklist (CBCL). Linear regression models were used to assess associations between bisphenols concentrations and both composite and syndrome CBCL scales. Exposure x child sex interactions were included in addition to their main effects and sex-stratified analyses were conducted. Models were adjusted for maternal age, number of siblings, and child age at CBCL intake. Mean maternal age was 29.7 years. Most women were White (88%), had an annual household income ≥$50,000 (66%), and at least a college degree (81%). Median concentrations were 1.3 ng/mL (range 0.4-7.2) for BPA and 0.3 ng/mL (range 0.1-3.5) for BPS. Sex modified the relationship between BPA and scores on several syndrome scales-anxious-depressed, aggressive, and sleep problems-where the association was consistently inverse in males in lower BPA concentrations, and positive (more reported behavior problems) among girls in the higher BPA group. Higher BPS was associated with more problematic internalizing behaviors among girls but not boys, and sex modified the relationship between BPS and emotionally reactive behaviors (Pinteraction = 0.128), with sex-specific estimates revealing more emotionally reactive behaviors among girls (expβ = 3.92 95% CI 1.16, 13.27; P = 0.028) but not boys. Findings were mixed overall, but one notable finding was that BPS, a replacement for BPA, was associated with increased problematic behaviors. There is a need for replication of findings due to our small sample size.

Measuring the intake of dietary bioactives: Pitfalls and how to avoid them

Bioactives are food constituents that, while not essential to human life, can affect health. Thus, there is increased interest in developing dietary recommendations for bioactives. Such recommendations require detailed information about the long-term association between habitual intake and health at population scale, and these can only be provided by large-scale observational studies. Nutritional epidemiology relies on the accurate estimation of intake, but currently used methods, commonly based on a 2-step process involving self-reports and food composition tables, are fraught with significant challenges and are unable to estimate the systemic presence of bioactives. Intake assessments based on nutritional biomarkers can provide an advanced alternative, but there are a number of pitfalls that need to be addressed in order to obtain reliable data on intake. Using flavan-3-ols as a case study, we highlight here key challenges and how they may be avoided. Taken together, we believe that the approaches outlined in this review can be applied to a wide range of food constituents, and doing so will improve assessments of the dietary intake of bioactives.

A cross-validation based approach for estimating specific gravity in elementary-school aged children using a nonlinear model

Environmental research often relies on urinary biomarkers which require dilution correction to accurately measure exposures. Specific gravity (SG) and creatinine (UCr) are commonly measured urinary dilution factors. Epidemiologic studies may assess only one of these measures, making it difficult to pool studies that may otherwise be able to be combined. Participants from the National Health and Nutrition Examination Survey 2007-2008 cycle were used to perform k-fold validation of a nonlinear model estimating SG from UCr. The final estimated model was applied to participants from the School Inner-City Asthma Intervention Study, who submitted urinary samples to the Children's Health Exposure Analysis Resource. Model performance was evaluated using calibration metrics to determine how closely the average estimated SG was to the measured SG. Additional models, with interaction terms for age, sex, body mass index, race/ethnicity, relative time of day when sample was collected, log transformed 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), and asthma status were estimated and assessed for improvement. The association between monobenzyl phthalate (MBZP) and asthma symptom days, controlling for measured UCr, measured SG, and each estimated SG were compared to assess validity of the estimated SG. The model estimating SG from UCr alone, resulted in a beta estimate of 1.10 (95% CI: 1.01, 1.19), indicating agreement between model-predicted SG and measured SG. Inclusion of age and sex in the model improved estimation (β = 1.06, 95% CI: 0.98, 1.15). The full model accounting for all interaction terms with UCr resulted in the best agreement (β = 1.01, 95% CI: 0.93,1.09). Associations between MBZP and asthma symptoms days, controlling for each estimated SG, were within the range of effect estimates when controlling for measured SG and measured UCr (Rate ratios = 1.28-1.34). Our nonlinear modeling provides opportunities to estimate SG in studies that measure UCr or vice versa, enabling data pooling despite differences in urine dilution factors.

Characterization of Urinary Pesticide Metabolite Concentrations of Pregnant Women in Suriname

Prenatal exposure to pesticides and the association with adverse health outcomes have been examined in several studies. However, the characterization of pesticide exposure among Surinamese women during pregnancy has not been assessed. As part of the Caribbean Consortium of Research in Environmental and Occupational Health research program, 214 urine samples were collected from pregnant women living in three regions in Suriname with different agricultural practices: capital Paramaribo, the rice producing district Nickerie, and the tropical rainforest, the Interior. We used isotope dilution tandem mass spectrometry to quantify urinary concentrations of biomarkers of three pesticide classes, including phenoxy acid herbicides and organophosphate and pyrethroid insecticides, all of which are commonly used in agricultural and residential settings in Suriname. We observed that participants residing in Nickerie had the highest urinary metabolite concentrations of 2,4-dichlorophenoxyacetic acid and pyrethroids compared to those from Paramaribo or the Interior. Paramaribo had the highest concentrations of organophosphate metabolites, specifically dialkyl phosphate metabolites. Para-nitrophenol was detected in samples from Paramaribo and the Interior. Samples from Nickerie had higher median urinary pesticide concentrations of 2,4-dichlorophenoxyacetic acid (1.06 μg/L), and the following metabolites, 3,5,6-trichloro-2-pyridinol (1.26 μg/L), 2-isopropyl-4-methyl-6-hydroxypyrimidine (0.60 μg/L), and 3-phenoxybenzoic acid (1.34 μg/L), possibly due to residential use and heavy rice production.

Smoking intensity and urinary nicotine metabolites by socioeconomic status in the Heinz Nixdorf Recall study

Background

Smoking intensity, which is generally based on self-reported average cigarettes per day (CPD), is a major behavioural risk factor and strongly related to socioeconomic status (SES). To assess the validity of the CPD measure, correlations with objective markers of tobacco smoke exposure – such as urinary nicotine metabolites – were examined. Yet, it remains unclear, whether this correlation is affected by SES, which may indicate imprecise or biased self-reports of smoking intensity.

Methods

We investigated the role of SES in the association between CPD and nicotine metabolites in current smokers among the participants of the population-based, prospective Heinz Nixdorf Recall Study. We determined urinary cotinine and additionally trans-3′-hydroxy-cotinine. SES was assessed by the International Socio-Economic Index of occupational status, and education. We calculated correlations (Pearson’s r) between logarithmised CPD and cotinine in subgroups of SES and analysed SES and further predictors of cotinine in multiple linear regression models separately by gender.

Results

Median reported smoking intensity was 20 CPD in male and 19 CPD in female smokers. Men showed higher cotinine concentrations (median 3652 μg/L, interquartile range (IQR) 2279–5422 μg/L) than women (3127 μg/L, IQR 1692–4920 μg/L). Logarithmised CPD correlated moderately with cotinine in both, men and women (Pearson’s r 0.4), but correlations were weaker in smokers with lower SES: Pearson’s r for low, intermediate, and high occupational SES was 0.35, 0.39, and 0.48 in men, and 0.28, 0.43, and 0.47 in women, respectively. Logarithmised CPD and urinary creatinine were main predictors of cotinine in multiple regression models, whereas SES showed a weak negative association in women. Results were similar for trans-3′-hydroxy-cotinine.

Conclusions

Decreasing precision of self-reported CPD was indicated for low SES in men and women. We found no strong evidence for biased self-reports of smoking intensity by SES.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-022-12609-y.

Comparison of Levels of Three Tobacco Smoke Exposure Biomarkers in Children of Smokers

Objectives: Cotinine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), and N-oxides are biomarkers of tobacco smoke exposure (TSE) used to assess short- and longer-term TSE. The objective of this study was to assess the associations between these TSE biomarkers, sociodemographics, parental smoking, and child TSE patterns among 0–17-year-olds. Methods: A convenience sample of 179 pediatric patients (mean (SD) age = 7.9 (4.3) years) who lived with ≥1 smoker and who had parental assessments completed and urine samples analyzed for the three TSE biomarkers of interest were included. Biomarker levels were log-transformed, univariate regression models were built and Pearson correlations were assessed. Results: In total, 100% of children had detectable levels of cotinine and >96% had detectable NNAL and N-oxide levels. The geometric means of cotinine, NNAL, and N-oxide levels were 10.1 ng/mL, 25.3 pg/mL, and 22.9 pg/mL, respectively. The mean (SD) number of daily cigarettes smoked by parents was 10.6 (6.0) cigarettes. Child age negatively correlated with urinary cotinine (r = −0.202, p = 0.007) and log NNAL levels (r = −0.275, p < 0.001). The highest log-cotinine levels were in children who were younger, of African American race, and whose parents had a lower education, an annual income ≤USD15,000, and no smoking bans. The highest log-NNAL and N-oxide levels were in children whose parents had a lower education, had no smoking bans, and were around higher numbers of cigarettes. Conclusion: Children of smokers who were younger, African American, and had no smoking bans had the highest TSE biomarker levels. Targeted interventions are needed to reduce TSE levels among high-risk children.

Peripheral markers of oxidative stress in Labrador retrievers with copper-associated hepatitis

OBJECTIVES

To evaluate biomarkers of oxidative stress in dogs with copper-associated hepatitis (CAH) as compared with healthy controls, and to evaluate if these markers correlate with hepatic copper concentrations and hepatic histopathologic features.

MATERIALS AND METHODS

Prospective study. Plasma reactive metabolite concentrations, plasma antioxidant potential, and plasma and urine isoprostane concentrations were determined in Labrador retrievers with copper-associated hepatitis (n=9) as well as in breed- and sex-matched (n=9) and age- and sex-matched (n=9) healthy control populations. Possible correlations between markers of oxidative stress and hepatic histopathological features also were investigated.

RESULTS

Reactive metabolites (median, range) were over twofold greater in dogs with copper-associated hepatitis (87.2 RFU/μL, 60.9 to 185.6 RFU/μL) as compared to breed- and sex-matched (38.2 RFU/μL, 22.4 to 116.8 RFU/μL) and age- and sex-matched controls (32.0 RFU/μL, 18.5 to 127.4 RFU/μL). Antioxidant potential was decreased in copper-associated hepatitis dogs (6.5 TE/μL, 5.1 to 7.7 TE/μL) as compared to breed- and sex-matched controls (8.2 TE/μL, 5.3 to 11.8 TE/μL). Both reactive metabolite concentrations and the reactive metabolite to antioxidant potential ratio were positively correlated with hepatic copper concentrations. Plasma and urine isoprostanes were variable and not significantly different between populations.

CLINICAL SIGNIFICANCE

Labrador retrievers with copper-associated hepatitis have altered oxidant status. Plasma reactive metabolite concentrations and the reactive metabolite to antioxidant potential ratio could be useful biomarkers. However, neither plasma nor urine isoprostanes were useful biomarkers for copper-associated hepatitis.

Short-term effects of ambient air pollution and outdoor temperature on biomarkers of myocardial damage, inflammation and oxidative stress in healthy adults

Supplemental Digital Content is available in the text.

The mechanisms whereby ambient air pollution and temperature changes promote cardiac events remain incompletely described. Seventy-three nonsmoking healthy adults (mean age 23.3, SD 5.4 years) were followed with up to four repeated visits across 15 months in Beijing in 2014–2016. Biomarkers relevant to myocardial damage (high-sensitivity cardiac troponin I [hs-cTnI]), inflammation (growth differentiation factor-15 [GDF-15]), and oxidative stress (8-hydroxy-2′-deoxyguanosine [8-OHdG]) were measured at each visit, while ambient air pollution and temperature were monitored throughout the study. Linear mixed-effects models coupled with distributed lag nonlinear models were used to assess the impacts of each exposure measure on study outcomes. During follow-up, average daily concentrations of fine particulate matter and outdoor temperature were 62.9 µg/m³ (8.1–331.0 µg/m³) and 10.1 °C (−6.5°C to 29.5°C). Serum hs-cTnI levels were detectable in 18.2% of blood samples, with 27.4% of individuals having ≥1 detectable values. Higher levels of ambient particulates and gaseous pollutants (per interquartile range) up to 14 days before clinical visits were associated with significant alterations in hs-cTnI levels of 22.9% (95% CI, 6.4, 39.4) to 154.7% (95% CI, 94.4, 215.1). These changes were accompanied by elevations of circulating GDF-15 and urinary 8-OHdG levels. Both low (5th percentile, −2.5 °C) and high (95th percentile, 24.8°C) outdoor temperatures, with breakpoint at ~13.0°C as the reference level, were also associated with elevations of hs-cTnI levels. Short-term exposure to ambient air pollution and temperature was associated with cardiac troponin, a biomarker of myocardial damage, along with increased inflammation and oxidative stress responses. These findings extend our understanding of the biological mechanisms linking pervasive environmental exposure to adverse cardiac events.

Clinical utility of urine specific gravity, electrical conductivity, and color as on-farm methods for evaluating urine concentration in dairy cattle

Background

Urine concentration (UC) provides clinically useful information concerning hydration status and renal function of animals.

Objectives

To characterize the clinical performance of urine specific gravity measured by optical refractometry (U_SG‐R) or Multistix‐SG urine reagent dipstick (U_SG‐D), urine electrical conductivity using an OAKTON Con 6 conductivity handheld meter (U_EC), urine color (U_Color) using a custom‐designed 8‐point color chart, and urine creatinine concentration (U_Creat) for assessing UC in dairy cattle.

Animals

20 periparturient Holstein‐Friesian cows.

Methods

Urine was obtained by perineal stimulation or urethral catheterization and urine osmolality (U_Osm, reference method), U_SG‐R, U_SG‐D, U_EC, U_Color, and U_Creat determined. Diagnostic test performance was evaluated using Spearman's rho and logistic regression to determine the area under the receiver operating curve (AUC) and optimal cut point for diagnosing hypohydration (U_Osm ≥800 mOsm/kg). P < .05 was considered significant.

Results

The best performing test for diagnosing hypohydration was U_SG‐R (AUC = 0.90) at an optimal cut point ≥1.030. The second‐best performing test was U_EC (AUC = 0.82) at a cut point of ≥23.7 mS/cm, followed by U_Creat (AUC = 0.76) at a cut point of ≥95.3 mg/dL, and U_Color (AUC = 0.74) at a cut point of ≥4 on an 8‐point scale. Urine specific gravity measured by dipstick performed poorly (AUC = 0.63).

Conclusions and Clinical Importance

U_SG‐R and U_EC provide practical and sufficiently accurate methods for measuring UC in dairy cattle. Urine color had moderate clinical utility as a no‐cost cow‐side method for assessing UC, whereas dipstick refractometry is not recommended for assessing UC.

For what factors should we normalize urinary extracellular mRNA biomarkers?

mRNA is a critical biomolecule involved in the manifestation of the genetic code into functional protein molecules. Its critical role in the central dogma has made it a key target in many studies to determine biomarkers and drug targets for numerous diseases. Currently, there is a growing body of evidence to suggest that RNA molecules around the size of full-length mRNA transcripts can be assayed in the supernatant of human urine and urinary extracellular mRNA could provide information about transcription in cells of urogenital tissues. However, the optimal means of normalizing these signals is unclear. In this paper, we describe relevant first principles as well as research findings from our lab and other labs toward normalization of urinary extracellular mRNA.

Bisphenol A and pubertal height growth in school-aged children

BACKGROUND

Bisphenol A (BPA) is an environmental endocrine disruptor and is found in many consumer products. Studies suggest that BPA may perturb pubertal development, although evidence on BPA-influenced pubertal height growth is scarce.

METHODS

A total of 754 children aged 9-18 years from three schools (one elementary, one middle, and one high school) in Shanghai were included in this longitudinal study. Height was measured at enrolment (visit 1) and, subsequently, at 19 months after enrolment (visit 2). Age- and sex-specific Z scores for height were calculated (height Z score = [participant's height-sex- and age-specific population height mean]/sex- and age-specific population height standard deviation). Urine samples were collected at enrolment to measure BPA concentrations. We used multiple linear regression models or general estimating equation models (GEE) to estimate associations between urine BPA level and height Z score.

RESULTS

The geometric mean of urine BPA concentrations was 1.6 μg/L (95%CI: 1.4, 1.8) or 1.2 μg/g creatinine (95%CI: 1.0, 1.3). An inverse association between urine BPA level and height was observed in boys. After adjustment for potential confounders, height Z score at enrolment in boys decreased by 0.49 for the highest exposure level (above 10.9 μg/g creatinine as the 90th percentile), compared with the lowest BPA exposure (below 0.2 μg/g creatinine as the 25th percentile) (95%CI: -0.96, -0.01; p-trend = 0.024). The inverse association remained between BPA exposure and height Z score at visit 2. The GEE model showed that a 1-unit increase in log₁₀-transformed BPA concentrations was associated with a 0.15-point decrease in height Z score over the follow-up (95%CI: -0.30, -0.01). BPA was not associated with height growth in girls.

CONCLUSIONS

Our findings indicate an inverse association between urine BPA level and height growth in boys. These findings need to be confirmed in further studies.

Urinary specific gravity as an alternative for the normalisation of endocrine metabolite concentrations in giant panda (Ailuropoda melanoleuca) reproductive monitoring

Reproductive monitoring for captive breeding in giant pandas is based on behavioural observation and non-invasive hormone analysis. In urine, interpretation of results requires normalisation due to an animal’s changing hydration. Correction of urinary concentrations based on creatinine is the gold standard. In this study, a largely unexplored, easy-to-perform normalisation technique, based on urinary specific gravity (USpG), was examined and compared to creatinine. To this extent, six cycles from two female pandas (SB741(1) and SB569(5)) were monitored through urine analysis for oestrogen, progesterone, ceruloplasmin and 13,14-dihydro-15-keto-PGF2a (PGFM). The Pearson’s correlation between creatinine and USpG was high (r = 0.805–0.894; p < 0.01), indicative for a similar performance of both normalisation methods. However, generally lower values were observed during pro-oestrus and primary (progesterone) rise. This could be associated with huge shifts in appetite, monitored by faecal output (kg) with an averaged > 50% decrease during oestrus and >50% increase during primary progesterone rise. In parallel, respectively highest and lowest creatinine and USpG levels, were measured, with creatinine obviously more affected as a result of linkage with muscle tissue metabolism affected by reproductive hormones. As a consequence, metabolite levels were significantly different between both corrected datasets with significantly higher oestrogen peak levels during oestrus ranging from 2.13–86.93 and 31.61–306.45 ng/mL (USpG correction) versus 2.33–31.20 and 36.36–249.05 ng/mL Cr (creatinine correction) for SB569 and SB741 respectively, and significant lower progesterone levels during primary progesterone rise ranging from 0.35–3.21 and 0.85–6.80 ng/mL (USpG correction) versus 0.52–10.31 and 2.10–272.74 ng/mL Cr (creatinine correction) for SB569 and SB741 respectively. Consequently, USpG correction rendered unbiased profiles, less subject to variation and metabolic artefacts and therefore allowed a more straightforward identification of peak oestrogen and onset of secondary progesterone rise, being potentially advantageous for future studies unravelling key giant panda reproductive events, including (delayed) implantation. The alternative application of USpG as a normalisation factor was further supported by its easy application and environmental and technical robustness.

Biological sex identification in the endangered dusky gopher frog (Lithobates sevosa): a comparison of body size measurements, secondary sex characteristics, ultrasound imaging, and urinary hormone analysis methods

BACKGROUND

Accurate sex identification techniques are important for wildlife demographic studies and for genetic management of captive breeding colonies. Various non-invasive methods for identification of biological sex in the weakly dimorphic endangered dusky gopher frog (DGF; Lithobates sevosa) were explored to support planned recovery efforts for this species including breeding and augmentation of wild populations.

METHODS

Body size (snout-vent length and body weight) measurements, observation of nuptial pads, ultrasound imaging, and urinary hormone analysis for testosterone and estrone were performed on 27 male and 19 female DGFs. For each method, the mean and range of measurement values were determined for male and female DGFs housed in a captive breeding population. The ability of these methods to accurately predict the true biological sex of the individuals was assessed retrospectively.

RESULTS

Body size measurements were of limited use for sex identification purposes, as males and females demonstrated overlapping body lengths and weights. Observation of the presence/absence of nuptial pads in males and females, respectively, proved to be accurate and easy to perform in most cases. Ultrasound imaging was useful for predicting the sex of female frogs, particularly when females were gravid. Commercial enzyme immunoassay kits were validated to measure urinary hormones in the DGF. Mean urinary testosterone (males: 2.22 ± 0.38 ng/ml; females: 0.92 ± 0.11 ng/ml) and estrone (males: 0.08 ± 0.01 ng/ml; females: 1.50 ± 0.39 ng/ml) concentrations were significantly (p < 0.05) different between the sexes. However, there was some overlap in hormone concentrations between the sexes. When a ratio of testosterone (T) to estrone (E) concentrations was calculated for each individual, males demonstrated significantly greater T/E ratios compared to females (p < 0.05). Use of this ratio showed greater accuracy in predicting the sex of the animal compared to using testosterone or estrone concentrations alone.

CONCLUSIONS

Monitoring for presence/absence of nuptial pads and using urinary testosterone to estrone hormone ratios were the most accurate methods for identifying the biological sex of adult DGFs. Urinary hormone measurements for sex identification may be useful in other weakly dimorphic and monomorphic amphibian species in both ex situ and in situ settings.

A Randomized Controlled Trial of Progressively Reduced Nicotine Content Cigarettes on Smoking Behaviors, Biomarkers of Exposure, and Subjective Ratings

BACKGROUND

The U.S. FDA has the authority to reduce cigarette nicotine content if found to benefit public health. Reduced nicotine content (RNC) cigarette use does not appear to increase harm exposure, but studies have not rigorously assessed smoking behavior or used a comprehensive panel of biomarkers. This study examined the effects of progressively decreasing RNC cigarettes on smoking behaviors, biomarkers of exposure, and subjective ratings.

METHODS

One hundred and fifty-eight daily, non-treatment-seeking smokers participated in a 35-day randomized, unblinded, parallel study. After a 5-day baseline period, participants were randomly assigned to an experimental group (n = 80) that smoked progressively decreasing RNC cigarettes during three 10-day periods, or control group (n = 78) that smoked their own brand throughout the study.

RESULTS

Daily cigarette consumption significantly increased for the intermediate RNCs (P's < 0.001) but approached baseline rate for the lowest RNC (P = 0.686); in contrast, puffing behavior significantly decreased at intermediate levels and increased for the lowest RNC (P's < 0.001). Cotinine and NNAL significantly decreased by RNC period (P's ≤ 0.001-0.02), whereas CO boost initially increased (P's = 0.001-0.005). 1-HOP did not change by period (P = 0.109).

CONCLUSIONS

Smoking behaviors changed by RNC period via CPD and puffing behavior. Biomarkers of exposure generally decreased with nicotine content.

IMPACT

Findings suggest that RNC use does not ubiquitously reduce smoking behaviors or biomarkers, yet the lowest RNC level tested may reduce harm exposure. This emphasizes the importance of using multiple behavioral and biologic measures to address the impact of RNC cigarette smoking. Cancer Epidemiol Biomarkers Prev; 25(7); 1125-33. ©2016 AACR.

Associations between Urinary Excretion of Cadmium and Renal Biomarkers in Nonsmoking Females: A Cross-Sectional Study in Rural Areas of South China

OBJECTIVES

The aim of this study was to systematically evaluate the relationship between urinary excretion of cadmium (U-Cd) and biomarkers of renal dysfunction.

METHODS

One hundred eighty five non-smoking female farmers (aged from 44 to 71 years) were recruited from two rural areas with different cadmium levels of exposure in southern China. Morning spot urine samples were collected for detecting U-Cd, urinary creatinine (U-cre), β₂-microglobulin (β₂-MG), α₁-microglobulin (α₁-MG), metallothionein (MT), retinol binding protein (RBP), albumin (AB), N-acetyl-β-D-glucosaminidase (NAG), alkaline phosphatase (ALP), γ-glutamyl transpeptidase (GGT) and kidney injury molecule-1 (KIM-1). Spearman's rank correlation was carried out to assess pairwise bivariate associations between continuous variables. Three different models of multiple linear regression (the cre-corrected, un-corrected and cre-adjusted model) were used to model the dose-response relationships between U-Cd and nine urine markers.

RESULTS

Spearman's rank correlation showed that NAG, ALP, RBP, β₂-MG and MT were significantly associated with U-Cd for both cre-corrected and observed data. Generally, NAG correlated best with U-Cd among the nine biomarkers studied, followed by ALP and MT. In the un-corrected model and cre-adjusted model, the regression coefficients and R² of nine biomarkers were larger than the corresponding values in the cre-corrected model, indicating that the use of observed data was better for investigating the relationship between biomarkers and U-Cd than cre-corrected data.

CONCLUSIONS

Our results suggest that NAG, MT and ALP in urine were better biomarkers for long-term environmental cadmium exposure assessment among the nine biomarkers studied. Further, data without normalization with creatinine show better relationships between cadmium exposure and renal dysfunction.

Urinary excretion of arsenic following rice consumption

Patterns of arsenic excretion were followed in a cohort (n = 6) eating a defined rice diet, 300 g per day d.wt. where arsenic speciation was characterized in cooked rice, following a period of abstinence from rice, and other high arsenic containing foods. A control group who did not consume rice were also monitored. The rice consumed in the study contained inorganic arsenic and dimethylarsinic acid (DMA) at a ratio of 1:1, yet the urine speciation was dominated by DMA (90%). At steady state (rice consumption/urinary excretion) ∼40% of rice derived arsenic was excreted via urine. By monitoring of each urine pass throughout the day it was observed that there was considerable variation (up to 13-fold) for an individual's total arsenic urine content, and that there was a time dependent variation in urinary total arsenic content. This calls into question the robustness of routinely used first pass/spot check urine sampling for arsenic analysis.

Impact of urine concentration adjustment method on associations between urine metals and estimated glomerular filtration rates (eGFR) in adolescents

Positive associations between urine toxicant levels and measures of glomerular filtration rate (GFR) have been reported recently in a range of populations. The explanation for these associations, in a direction opposite that of traditional nephrotoxicity, is uncertain. Variation in associations by urine concentration adjustment approach has also been observed. Associations of urine cadmium, thallium and uranium in models of serum creatinine- and cystatin-C-based estimated GFR (eGFR) were examined using multiple linear regression in a cross-sectional study of adolescents residing near a lead smelter complex. Urine concentration adjustment approaches compared included urine creatinine, urine osmolality and no adjustment. Median age, blood lead and urine cadmium, thallium and uranium were 13.9 years, 4.0 μg/dL, 0.22, 0.27 and 0.04 g/g creatinine, respectively, in 512 adolescents. Urine cadmium and thallium were positively associated with serum creatinine-based eGFR only when urine creatinine was used to adjust for urine concentration (β coefficient=3.1 mL/min/1.73 m(2); 95% confidence interval=1.4, 4.8 per each doubling of urine cadmium). Weaker positive associations, also only with urine creatinine adjustment, were observed between these metals and serum cystatin-C-based eGFR and between urine uranium and serum creatinine-based eGFR. Additional research using non-creatinine-based methods of adjustment for urine concentration is necessary.

Time to first cigarette predicts 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) in adolescent regular and intermittent smokers, National Health and Nutrition and Examination Survey (NHANES) 2007-10

BACKGROUND AND AIMS

The time to first cigarette (TTFC) of the day is an indicator of nicotine intake in adults and adolescents. However, the relation between TTFC and biological markers of nicotine addiction and health risk in youths has not been well described. The current study examined whether an earlier TTFC predicts higher levels of a tobacco-specific carcinogen, 4-(methylnitrosamino)-1-(3-pyridal)-1 (NNAL), in regular and intermittent adolescent smokers and if this relation is mediated by nicotine intake (measured by cotinine) or cigarettes per day (CPD).

DESIGN

A cross-sectional analysis of a nationally representative subsample of adolescents.

SETTING

A general community sample from the 2007-08 and 2009-10 National Health and Nutrition and Examination Survey.

PARTICIPANTS

A total of 215 adolescents in the United States between the ages of 12 and 19 years who reported smoking at least once in the 5 days prior to data collection.

MEASUREMENTS

The primary outcome measure was urinary levels of NNAL.

FINDINGS

In both regular and intermittent smokers, earlier TTFC was associated dose-dependently with higher levels of NNAL (P < 0.03 in both cases). TTFC had an indirect effect on NNAL, mediated by nicotine intake (cotinine) in both regular [β = -0.08, standard error (SE) = 0.03, 95% confidence interval (CI) = -0.15, -0.03] and intermittent (β = -0.02, SE = 0.01, 95% CI = -0.05, -0.002) smokers. CPD was not found to be an important mediator of the relation between TTFC and NNAL.

CONCLUSIONS

Time between waking and the first cigarette of the day is correlated in daily and non-daily adolescent smokers with overall nicotine and therefore carcinogen intake.

Comparison of creatinine and specific gravity for hydration corrections on measurement of the tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) in urine

BACKGROUND

Tobacco-specific carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) was measured in all participants aged 6 years and older from the Centers for Disease Control and Prevention's National Health and Nutrition Examination Survey 2007-2008. The suitability of using creatinine or specific gravity for urinary NNAL correction in exposure assessment is examined in this study.

METHODS

Effects of both specific gravity and creatinine correction on urinary NNAL among smokers were investigated with multiple linear regression models using either normalization or the fitting of creatinine and specific gravity in the model as covariates.

RESULTS

When log-scaled NNAL was normalized by either creatinine or specific gravity, R(2) was slightly higher for creatinine than for specific gravity (R(2) = 0.1694 and 0.1439, for creatinine and specific gravity, respectively). When log-scaled NNAL was normalized by both factors, the R(2) was improved (R(2) = 0.2068). When specific gravity or creatinine was included as a covariate separately in the models, they were highly significant factors (P < 0.001, R(2) = 0.2226 and 0.1681 for creatinine and specific gravity, respectively). However, when both were included in the model as covariates, creatinine remained highly significant (P < 0.001), whereas the significance of specific gravity was eliminated (P = 0.4294).

CONCLUSION

This study confirms significant relationships between NNAL concentrations and both urine creatinine and specific gravity. We conclude that creatinine is the more influential and preferred variable to account for urine dilution in tobacco-specific nitrosamine exposure assessment.

Changes of urinary phospholipids in the chronic kidney disease patients

OBJECTIVE

To evaluate whether urinary phospholipids could be regarded as biomarkers of chronic kidney disease.

MATERIALS AND METHODS

Thirteen healthy volunteers and 26 consecutive chronic kidney disease patients were included. Urinary phospholipids were quantified by high-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry.

RESULTS

Urinary phosphatidylcholines concentrations (PC 16:0/16:0, 16:0/22:3, 16:0/18:1 and 16:0/18:2) were significantly higher both in glomerulonephritis group (all p < 0.001) and in tubulointerstitial injury group (all p < 0.05) than in healthy control group. Meanwhile, sphingomyelin concentrations (SM 18:1/16:0 and 18:1/18:0) in glomerulonephritis group were significantly higher than those in healthy control group (all p < 0.001). Urinary PCs and SMs were positively correlated with proteinuria but negatively correlated with serum albumin. Meanwhile, PCs were positively correlated with serum creatinine.

CONCLUSION

Our work first demonstrated that urinary phospholipids might be biomarkers for the chronic kidney disease patients. Increased urinary phospholipids in chronic kidney disease patients might result from proteinuria, damaged kidney function or proteinuria induced hypoalbuminemia or lipotoxicity.