Parabens are broad-spectrum antimicrobial preservatives and fragrances used in a wide range of pe... more Parabens are broad-spectrum antimicrobial preservatives and fragrances used in a wide range of personal care products, pharmaceuticals, and food providing the opportunity for people to be exposed on a daily basis. In 2009−2010, 80 pregnant women from Ottawa Canada participated in the Plastics and Personal-Care Product Use in Pregnancy (P4) Study. A subset of women (n = 31) who provided multiple spot urine samples (n = 542) collected over two 24-h periods had their samples analyzed for methylparaben (MP), npropylparaben (PP), ethylparaben (EP), butylparaben (BP), isobutylparaben (IBP), and benzylparaben (BzP). These parabens were also measured in breast milk samples collected at approximately 3 months postpartum (n = 56 women). Women kept a diary of products that they used 24 h prior to and during the collection. All parabens measured in maternal urine had moderate to high reproducibility. Women who used lotions in the past 24 h had significantly higher geometric mean paraben concentrations (80−110%) in their urine than women who reported no use in the past 24 h. Women who used shampoo, conditioner, and cosmetics also showed 70−80% higher BP concentrations in their urine. Breast milk samples had >50% detection for MP, PP, and EP.
ABSTRACT High-performance liquid chromatography-thermospray mass spectrometry was applied to the ... more ABSTRACT High-performance liquid chromatography-thermospray mass spectrometry was applied to the analysis of various radiation-induced decomposition products of thymidine including N-(2-deoxy-beta-D-erythro-pentofuranosyl)formamide and the various diastereomers of 5,6-dihydroxy-5,6-dihydrothymidine, 5-hydroxy-5,6-dihydrothymidine and 5,6-dihydrothymidine. This method combines high sensitivity and product resolution, rendering it particularly useful for monitoring the formation of radiation-induced base damage within DNA.
Phthalates and bisphenol A (BPA) are high production volume and ubiquitous chemicals that are qui... more Phthalates and bisphenol A (BPA) are high production volume and ubiquitous chemicals that are quickly metabolized in the body. Traditionally, studies have relied on single spot urine analyses to assess exposure; ignoring variability in concentrations throughout a day or over a longer period of time. We compared BPA and phthalate metabolite results from urine samples collected at five different time points. Participants (n = 80) were asked to collect all voids in a 24 h period on a weekday and then again on a weekend before 20 weeks of pregnancy. During the second and third trimesters and in the postpartum period, single spot urines were collected. Variability over time in urinary concentrations was assessed using intraclass correlation coefficients (ICCs) and the sensitivity to correctly classify a single sample as high or low versus the geometric mean (GM) of all samples was calculated. We found low reproducibility and sensitivity of BPA and all phthalate metabolites throughout pre...
A method was developed for sensitive and robust monitoring of very low levels of polycyclic aroma... more A method was developed for sensitive and robust monitoring of very low levels of polycyclic aromatic hydrocarbons (PAH) metabolites in urine using the Agilent 7000B Triple Quadrupole GC/MS System. The resulting limits of detection (LODs) were as low as 0.7 parts per trillion (ppt), and limits of quantitation (LOQs) were as low as 2.5 ppt, with nearly 100% recovery for all 19 PAH metabolites. This method was developed for current use by the Canadian Health Measures Survey (CHMS).
Parabens, phthalates and phenols are found in a large range of personal care products and food an... more Parabens, phthalates and phenols are found in a large range of personal care products and food and beverage packaging, providing the opportunity for people to be exposed on a daily basis. In 2009&#...
The matrix effects (MEs) on the quantification of an analyte can be significant and should not be... more The matrix effects (MEs) on the quantification of an analyte can be significant and should not be neglected during development and validation of an analytical method. According to this premise, we developed a standardized procedure based on a set of six tests performed on six different sample matrices to detect and characterize the effects of the matrix for single and multiple analytes methods. The link between the matrix effect, recovery, process efficiency, accuracy, precision, and calibration curve was underscored by calculations performed with peak areas, ratios of standard/ internal standard peak area, and concentrations. The terms instrumental ME and global ME were introduced, and the term recovery was subdivided for clarity. The test accounts for the presence of ubiquitous and endogenous analytes through background subtraction. The results showed the necessity for using samples with an original concentration in the same range and that the concentration selected for the addition had a definite impact on the results. The use of six-sample matrices provided a standard deviation on the results, and this information could be inserted in a method performance result to show precision. The tool also allows for testing of different analytes/internal standard combinations, which helps with the selection of the association with minimum MEs. A UPLC-MS/MS method for the quantification of several phthalate metabolites in urine was developed and validated with this test. This methodology responds to a scientific need for homogeneity, clarity, and understanding of the results and facilitates the decision-making process while lowering the required costs and time.
Parabens are broad-spectrum antimicrobial preservatives and fragrances used in a wide range of pe... more Parabens are broad-spectrum antimicrobial preservatives and fragrances used in a wide range of personal care products, pharmaceuticals, and food providing the opportunity for people to be exposed on a daily basis. In 2009-2010, 80 pregnant women from Ottawa Canada participated in the Plastics and Personal-Care Product Use in Pregnancy (P4) Study. A subset of women (n = 31) who provided multiple spot urine samples (n = 542) collected over two 24-h periods had their samples analyzed for methylparaben (MP), n-propylparaben (PP), ethylparaben (EP), butylparaben (BP), isobutylparaben (IBP), and benzylparaben (BzP). These parabens were also measured in breast milk samples collected at approximately 3 months postpartum (n = 56 women). Women kept a diary of products that they used 24 h prior to and during the collection. All parabens measured in maternal urine had moderate to high reproducibility. Women who used lotions in the past 24 h had significantly higher geometric mean paraben concen...
We hypothesize that androgen deficiency is a critical etiologic factor in the pathogenesis of aqu... more We hypothesize that androgen deficiency is a critical etiologic factor in the pathogenesis of aqueous-deficient and evaporative dry eye in Sjögren's syndrome (SS). We investigated whether women with SS have a deficiency in total androgens. We also examined whether these patients have elevated serum concentrations of estrogens. Blood was drawn from women with primary and secondary SS and age matched controls, and analyzed for steroid concentrations by gas and liquid chromatography-mass spectrometry. Our results show that women with SS are androgen-deficient. Concentrations of 5-androstene-3beta,17beta-diol (5-diol), dehydroepiandrosterone (DHEA), dihydrotestosterone (DHT), androsterone-glucuronide (ADT-G), and androstane-3a,17beta-diol-G (3alpha-diol-G) were all significantly reduced in SS sera relative to controls. In contrast, SS was not associated with significant alterations in the serum concentrations of testosterone, androstenedione, estrone, or 17beta-estradiol. These over...
Journal of Exposure Science & Environmental Epidemiology, 2014
Phthalates and bisphenol A (BPA) are high production volume and ubiquitous chemicals that are qui... more Phthalates and bisphenol A (BPA) are high production volume and ubiquitous chemicals that are quickly metabolized in the body. Traditionally, studies have relied on single spot urine analyses to assess exposure; ignoring variability in concentrations throughout a day or over a longer period of time. We compared BPA and phthalate metabolite results from urine samples collected at five different time points. Participants (n = 80) were asked to collect all voids in a 24 h period on a weekday and then again on a weekend before 20 weeks of pregnancy. During the second and third trimesters and in the postpartum period, single spot urines were collected. Variability over time in urinary concentrations was assessed using intraclass correlation coefficients (ICCs) and the sensitivity to correctly classify a single sample as high or low versus the geometric mean (GM) of all samples was calculated. We found low reproducibility and sensitivity of BPA and all phthalate metabolites throughout pregnancy and into the postpartum period but much higher reproducibility within a day. Time of day when the urine was collected was a significant predictor of specific gravity adjusted exposure levels. We concluded that, if the interest is in average exposures across pregnancy, maternal/fetal exposure estimation may be more accurate if multiple measurements, collected across the course of the entire pregnancy, rather than a single spot measure, are performed.
Results of recent national surveys have shown the high prevalence of exposure to bisphenol A (BPA... more Results of recent national surveys have shown the high prevalence of exposure to bisphenol A (BPA) and triclosan (TCS) among the general population; however biomonitoring data for pregnant women and infants are limited. Women (n=80) were recruited from early prenatal clinics and asked to collect urine samples multiple times during pregnancy and once 2-3months post-partum. Samples of infant urine and meconium as well as breast milk and infant formula were also collected. Biospecimens were analyzed by GC-MS/MS for BPA, TCS and triclocarban (TCC). Triclosan was detected in over 80% of the maternal urines (geometric mean (GM): 21.61μg/L), 60% of the infant urines (GM: 2.8μg/L), 46% of the breast milk and 80% of the meconium samples. Triclocarban was rarely detected in any of the biospecimens. Median total BPA concentrations were 1.21 and 0.24μg/L in maternal and infant urines, respectively. Free BPA was detected in only 11% of infant urine samples. The meconium of female infants had sig...
The Journal of steroid biochemistry and molecular biology, 2007
The marked decline in serum dehydroepiandrosterone (DHEA) with age is believed to play a role in ... more The marked decline in serum dehydroepiandrosterone (DHEA) with age is believed to play a role in health problems associated with aging, these health issues being potentially preventable or reversible by the exogenous administration of DHEA. In the present study, liquid chromatography/mass spectrometry/mass spectrometry (LC/MS/MS) and gas chromatrography/mass spectrometry (GC/MS) were used to measure the serum levels of DHEA and 11 of its metabolites in seventy-five 60-65-year-old Caucasian women who received 3g of 0.1%, 0.3%, 1.0% or 2.0% DHEA cream or placebo applied twice daily on the face, upper chest, arms and legs. The serum levels of DHEA increased 574% over control at the 2.0% DHEA dose while the sum of the androgen metabolites androsterone glucuronide (ADT-G), 3alpha-androstenediol-3G (3alpha-diol-3G) and 3alpha-diol-17G increased by only 231%. On the other hand, serum testosterone and dihydrosterone were increased by 192% and 275%, respectively, above basal levels compared ...
We thank V. Choeurng and C.L. Liang for their statistical support and R. Nysen for the use of her... more We thank V. Choeurng and C.L. Liang for their statistical support and R. Nysen for the use of her SAS code to impute the left-censored test for normality. We especially appreciate the essential contributions of the MIREC participants and staff and the MIREC Study Group.
The Journal of Steroid Biochemistry and Molecular Biology, 2009
The objective of this study was comparison of circulating androgens and their metabolites as well... more The objective of this study was comparison of circulating androgens and their metabolites as well as estrogens measured for the first time by a validated mass spectrometry technology in 60-80-year-old men and women of comparable age. Castration in men (n = 34) reduces the total androgen pool by only about 60% as indicated by the decrease in the serum levels of the glucuronide metabolites of androgens compared to intact men (n = 1302). Such data are in agreement with the 50 to 75% decrease in intraprostatic dihydrotestosterone (DHT) concentration after castration. Most interestingly, the same amounts of androgens and estrogens are found in postmenopausal women (n = 369) and castrated men of comparable age. The most significant therapeutic implication of these findings is the absolute need to add a pure (nonsteroidal) antiandrogen to castration in men with prostate cancer in order to block the action of the 25 to 50% DHT left in the prostate after castration. Not adding an antiandrogen to castration in men treated for prostate cancer is equivalent to not prescribing a blocker of estrogens in women suffering from breast cancer because they are postmenopausal and have low circulating estradiol.
The Journal of Steroid Biochemistry and Molecular Biology, 2006
Despite the long series of cohort studies performed during the last 20 years, the correlation bet... more Despite the long series of cohort studies performed during the last 20 years, the correlation between serum testosterone and any clinical situation believed to be under androgen control in women has remained elusive. This is likely related to the recent finding that the androgens made locally in large amounts in peripheral tissues from the precursor dehydroepiandrosterone (DHEA) act in the same cells where synthesis takes place and are not released in significant amounts in the circulation, thus making unreliable the measurement of serum testosterone as marker of total androgenic activity. The objective is to determine if serum androgen glucuronides can be replaced by testosterone or another steroid as measure of androgenic activity. Since the glucuronide derivatives of androgens are the obligatory route of elimination of all androgens, these metabolites were measured by liquid chromatography tandem mass spectrometry under basal conditions in 377 healthy postmenopausal women aged 55-65 years as well as in 47 premenopausal women aged 30-35 years while testosterone was assayed by gas chromatography mass spectrometry. No correlation was found between the serum concentration of testosterone and that of androsterone glucuronide (ADT-G) or androstenediol glucuronide (3␣-diol-G), the androgen metabolites which account for the total pool of androgens. The present data show that measurement of the total pool of androgens reflected by the serum levels of ADT-G and 3␣-diol-G cannot be replaced by serum testosterone or any other steroid, including DHEA or DHEA sulphate. These findings may have implications for women with androgen deficiency involving osteoporosis, obesity, type 2 diabetes, sexual dysfunction, loss of muscular strength and a series of other clinical situations affecting women's health. Measuring ADT-G and 3␣-diol-G might identify cases of true androgen deficiency and provide an opportunity to offer appropriate androgen therapy.
The Journal of Steroid Biochemistry and Molecular Biology, 2008
Healthy postmenopausal women aged 60-65 years (n = 150) were randomized to receive twice daily ap... more Healthy postmenopausal women aged 60-65 years (n = 150) were randomized to receive twice daily application on the skin of 3 g of a 0.3% dehydroepiandrosterone (DHEA) or placebo emulsion for 12 months. Serum DHEA and eleven of its metabolites were measured at screening and on day 1, as well as at 1, 3, 6, 9 and 12 months to study long-term metabolism. While serum DHEA and androst-5-ene-3, 17-diol (5-diol) increased by 203% and 178%, respectively, on average, during the 12-month period, the sum of concentrations of the metabolites of androgens, namely androsterone glucuronide (ADT-G), androstane-3␣,17-diol-3G and-17G increased by only 71% while usually non statistically significant changes of 30%, 17% and 20% were observed for estrone (E 1), estradiol (E 2) and E 1 sulfate (E 1-S), respectively. Despite the return of serum DHEA to normal premenopausal values with the present DHEA treatment regimen, the 65% decrease in the androgen pool found in this group of postmenopausal women is in fact corrected by only 24%, thus remaining 41% below the values found in normal premenopausal women. In fact, the changes in serum DHEA observed after percutaneous DHEA administration are a 186% overestimate of the true changes in androgen formation while the overestimate of estrogen production is even much higher. On the other hand, the pharmacokinetics of the steroids are stable over the 12-month period with no significant induction or decrease of activity of the enzymatic systems transforming DHEA predominantly into androgens.
The Journal of Steroid Biochemistry and Molecular Biology, 2013
In order to avoid the risks of non-physiological systemic exposure, serum concentrations of estra... more In order to avoid the risks of non-physiological systemic exposure, serum concentrations of estradiol (E 2) and testosterone (as measured by mass spectrometry-based assays) should remain below the 95th centiles measured at 9.3 pg/ml and 0.26 ng/ml for these respective sex steroids in normal postmenopausal women. To document the possibility of achieving this therapeutic objective, we have measured individual 24 h serum E 2 and testosterone concentrations in women with vulvovaginal atrophy (VVA) receiving daily intravaginal administration of a clinically effective dose of 6.5 mg prasterone (dehydroepiandrosterone, DHEA). Serum E 2 and testosterone, as well as DHEA and nine of its other metabolites, were assayed at ten time intervals over 24 h on the first and seventh days of daily vaginal administration of 6.5 mg prasterone. No significant change from baseline of average 24 h serum E 2 or testosterone concentrations was observed. Moreover, average 24 h serum DHEA remained within the normal postmenopausal range. Estrone sulfate and the androgen metabolites androsterone glucuronide and androstane-3␣, 17-diol glucuronide did not change, thus confirming the absence of any biologically relevant systemic exposure to estrogens and androgens, respectively. Serum concentrations of metabolites of both estrogens and androgens remain within the normal postmenopausal range following daily intravaginal administration of 6.5 mg prasterone. As other studies have shown, local formation of sex steroids in peripheral tissues without significant release of E 2 or testosterone in the circulation can be achieved with intravaginal prasterone. Thus, prasterone is a promising physiological and attractive solution to treating VVA symptoms.
Parabens are broad-spectrum antimicrobial preservatives and fragrances used in a wide range of pe... more Parabens are broad-spectrum antimicrobial preservatives and fragrances used in a wide range of personal care products, pharmaceuticals, and food providing the opportunity for people to be exposed on a daily basis. In 2009−2010, 80 pregnant women from Ottawa Canada participated in the Plastics and Personal-Care Product Use in Pregnancy (P4) Study. A subset of women (n = 31) who provided multiple spot urine samples (n = 542) collected over two 24-h periods had their samples analyzed for methylparaben (MP), npropylparaben (PP), ethylparaben (EP), butylparaben (BP), isobutylparaben (IBP), and benzylparaben (BzP). These parabens were also measured in breast milk samples collected at approximately 3 months postpartum (n = 56 women). Women kept a diary of products that they used 24 h prior to and during the collection. All parabens measured in maternal urine had moderate to high reproducibility. Women who used lotions in the past 24 h had significantly higher geometric mean paraben concentrations (80−110%) in their urine than women who reported no use in the past 24 h. Women who used shampoo, conditioner, and cosmetics also showed 70−80% higher BP concentrations in their urine. Breast milk samples had >50% detection for MP, PP, and EP.
ABSTRACT High-performance liquid chromatography-thermospray mass spectrometry was applied to the ... more ABSTRACT High-performance liquid chromatography-thermospray mass spectrometry was applied to the analysis of various radiation-induced decomposition products of thymidine including N-(2-deoxy-beta-D-erythro-pentofuranosyl)formamide and the various diastereomers of 5,6-dihydroxy-5,6-dihydrothymidine, 5-hydroxy-5,6-dihydrothymidine and 5,6-dihydrothymidine. This method combines high sensitivity and product resolution, rendering it particularly useful for monitoring the formation of radiation-induced base damage within DNA.
Phthalates and bisphenol A (BPA) are high production volume and ubiquitous chemicals that are qui... more Phthalates and bisphenol A (BPA) are high production volume and ubiquitous chemicals that are quickly metabolized in the body. Traditionally, studies have relied on single spot urine analyses to assess exposure; ignoring variability in concentrations throughout a day or over a longer period of time. We compared BPA and phthalate metabolite results from urine samples collected at five different time points. Participants (n = 80) were asked to collect all voids in a 24 h period on a weekday and then again on a weekend before 20 weeks of pregnancy. During the second and third trimesters and in the postpartum period, single spot urines were collected. Variability over time in urinary concentrations was assessed using intraclass correlation coefficients (ICCs) and the sensitivity to correctly classify a single sample as high or low versus the geometric mean (GM) of all samples was calculated. We found low reproducibility and sensitivity of BPA and all phthalate metabolites throughout pre...
A method was developed for sensitive and robust monitoring of very low levels of polycyclic aroma... more A method was developed for sensitive and robust monitoring of very low levels of polycyclic aromatic hydrocarbons (PAH) metabolites in urine using the Agilent 7000B Triple Quadrupole GC/MS System. The resulting limits of detection (LODs) were as low as 0.7 parts per trillion (ppt), and limits of quantitation (LOQs) were as low as 2.5 ppt, with nearly 100% recovery for all 19 PAH metabolites. This method was developed for current use by the Canadian Health Measures Survey (CHMS).
Parabens, phthalates and phenols are found in a large range of personal care products and food an... more Parabens, phthalates and phenols are found in a large range of personal care products and food and beverage packaging, providing the opportunity for people to be exposed on a daily basis. In 2009&#...
The matrix effects (MEs) on the quantification of an analyte can be significant and should not be... more The matrix effects (MEs) on the quantification of an analyte can be significant and should not be neglected during development and validation of an analytical method. According to this premise, we developed a standardized procedure based on a set of six tests performed on six different sample matrices to detect and characterize the effects of the matrix for single and multiple analytes methods. The link between the matrix effect, recovery, process efficiency, accuracy, precision, and calibration curve was underscored by calculations performed with peak areas, ratios of standard/ internal standard peak area, and concentrations. The terms instrumental ME and global ME were introduced, and the term recovery was subdivided for clarity. The test accounts for the presence of ubiquitous and endogenous analytes through background subtraction. The results showed the necessity for using samples with an original concentration in the same range and that the concentration selected for the addition had a definite impact on the results. The use of six-sample matrices provided a standard deviation on the results, and this information could be inserted in a method performance result to show precision. The tool also allows for testing of different analytes/internal standard combinations, which helps with the selection of the association with minimum MEs. A UPLC-MS/MS method for the quantification of several phthalate metabolites in urine was developed and validated with this test. This methodology responds to a scientific need for homogeneity, clarity, and understanding of the results and facilitates the decision-making process while lowering the required costs and time.
Parabens are broad-spectrum antimicrobial preservatives and fragrances used in a wide range of pe... more Parabens are broad-spectrum antimicrobial preservatives and fragrances used in a wide range of personal care products, pharmaceuticals, and food providing the opportunity for people to be exposed on a daily basis. In 2009-2010, 80 pregnant women from Ottawa Canada participated in the Plastics and Personal-Care Product Use in Pregnancy (P4) Study. A subset of women (n = 31) who provided multiple spot urine samples (n = 542) collected over two 24-h periods had their samples analyzed for methylparaben (MP), n-propylparaben (PP), ethylparaben (EP), butylparaben (BP), isobutylparaben (IBP), and benzylparaben (BzP). These parabens were also measured in breast milk samples collected at approximately 3 months postpartum (n = 56 women). Women kept a diary of products that they used 24 h prior to and during the collection. All parabens measured in maternal urine had moderate to high reproducibility. Women who used lotions in the past 24 h had significantly higher geometric mean paraben concen...
We hypothesize that androgen deficiency is a critical etiologic factor in the pathogenesis of aqu... more We hypothesize that androgen deficiency is a critical etiologic factor in the pathogenesis of aqueous-deficient and evaporative dry eye in Sjögren's syndrome (SS). We investigated whether women with SS have a deficiency in total androgens. We also examined whether these patients have elevated serum concentrations of estrogens. Blood was drawn from women with primary and secondary SS and age matched controls, and analyzed for steroid concentrations by gas and liquid chromatography-mass spectrometry. Our results show that women with SS are androgen-deficient. Concentrations of 5-androstene-3beta,17beta-diol (5-diol), dehydroepiandrosterone (DHEA), dihydrotestosterone (DHT), androsterone-glucuronide (ADT-G), and androstane-3a,17beta-diol-G (3alpha-diol-G) were all significantly reduced in SS sera relative to controls. In contrast, SS was not associated with significant alterations in the serum concentrations of testosterone, androstenedione, estrone, or 17beta-estradiol. These over...
Journal of Exposure Science & Environmental Epidemiology, 2014
Phthalates and bisphenol A (BPA) are high production volume and ubiquitous chemicals that are qui... more Phthalates and bisphenol A (BPA) are high production volume and ubiquitous chemicals that are quickly metabolized in the body. Traditionally, studies have relied on single spot urine analyses to assess exposure; ignoring variability in concentrations throughout a day or over a longer period of time. We compared BPA and phthalate metabolite results from urine samples collected at five different time points. Participants (n = 80) were asked to collect all voids in a 24 h period on a weekday and then again on a weekend before 20 weeks of pregnancy. During the second and third trimesters and in the postpartum period, single spot urines were collected. Variability over time in urinary concentrations was assessed using intraclass correlation coefficients (ICCs) and the sensitivity to correctly classify a single sample as high or low versus the geometric mean (GM) of all samples was calculated. We found low reproducibility and sensitivity of BPA and all phthalate metabolites throughout pregnancy and into the postpartum period but much higher reproducibility within a day. Time of day when the urine was collected was a significant predictor of specific gravity adjusted exposure levels. We concluded that, if the interest is in average exposures across pregnancy, maternal/fetal exposure estimation may be more accurate if multiple measurements, collected across the course of the entire pregnancy, rather than a single spot measure, are performed.
Results of recent national surveys have shown the high prevalence of exposure to bisphenol A (BPA... more Results of recent national surveys have shown the high prevalence of exposure to bisphenol A (BPA) and triclosan (TCS) among the general population; however biomonitoring data for pregnant women and infants are limited. Women (n=80) were recruited from early prenatal clinics and asked to collect urine samples multiple times during pregnancy and once 2-3months post-partum. Samples of infant urine and meconium as well as breast milk and infant formula were also collected. Biospecimens were analyzed by GC-MS/MS for BPA, TCS and triclocarban (TCC). Triclosan was detected in over 80% of the maternal urines (geometric mean (GM): 21.61μg/L), 60% of the infant urines (GM: 2.8μg/L), 46% of the breast milk and 80% of the meconium samples. Triclocarban was rarely detected in any of the biospecimens. Median total BPA concentrations were 1.21 and 0.24μg/L in maternal and infant urines, respectively. Free BPA was detected in only 11% of infant urine samples. The meconium of female infants had sig...
The Journal of steroid biochemistry and molecular biology, 2007
The marked decline in serum dehydroepiandrosterone (DHEA) with age is believed to play a role in ... more The marked decline in serum dehydroepiandrosterone (DHEA) with age is believed to play a role in health problems associated with aging, these health issues being potentially preventable or reversible by the exogenous administration of DHEA. In the present study, liquid chromatography/mass spectrometry/mass spectrometry (LC/MS/MS) and gas chromatrography/mass spectrometry (GC/MS) were used to measure the serum levels of DHEA and 11 of its metabolites in seventy-five 60-65-year-old Caucasian women who received 3g of 0.1%, 0.3%, 1.0% or 2.0% DHEA cream or placebo applied twice daily on the face, upper chest, arms and legs. The serum levels of DHEA increased 574% over control at the 2.0% DHEA dose while the sum of the androgen metabolites androsterone glucuronide (ADT-G), 3alpha-androstenediol-3G (3alpha-diol-3G) and 3alpha-diol-17G increased by only 231%. On the other hand, serum testosterone and dihydrosterone were increased by 192% and 275%, respectively, above basal levels compared ...
We thank V. Choeurng and C.L. Liang for their statistical support and R. Nysen for the use of her... more We thank V. Choeurng and C.L. Liang for their statistical support and R. Nysen for the use of her SAS code to impute the left-censored test for normality. We especially appreciate the essential contributions of the MIREC participants and staff and the MIREC Study Group.
The Journal of Steroid Biochemistry and Molecular Biology, 2009
The objective of this study was comparison of circulating androgens and their metabolites as well... more The objective of this study was comparison of circulating androgens and their metabolites as well as estrogens measured for the first time by a validated mass spectrometry technology in 60-80-year-old men and women of comparable age. Castration in men (n = 34) reduces the total androgen pool by only about 60% as indicated by the decrease in the serum levels of the glucuronide metabolites of androgens compared to intact men (n = 1302). Such data are in agreement with the 50 to 75% decrease in intraprostatic dihydrotestosterone (DHT) concentration after castration. Most interestingly, the same amounts of androgens and estrogens are found in postmenopausal women (n = 369) and castrated men of comparable age. The most significant therapeutic implication of these findings is the absolute need to add a pure (nonsteroidal) antiandrogen to castration in men with prostate cancer in order to block the action of the 25 to 50% DHT left in the prostate after castration. Not adding an antiandrogen to castration in men treated for prostate cancer is equivalent to not prescribing a blocker of estrogens in women suffering from breast cancer because they are postmenopausal and have low circulating estradiol.
The Journal of Steroid Biochemistry and Molecular Biology, 2006
Despite the long series of cohort studies performed during the last 20 years, the correlation bet... more Despite the long series of cohort studies performed during the last 20 years, the correlation between serum testosterone and any clinical situation believed to be under androgen control in women has remained elusive. This is likely related to the recent finding that the androgens made locally in large amounts in peripheral tissues from the precursor dehydroepiandrosterone (DHEA) act in the same cells where synthesis takes place and are not released in significant amounts in the circulation, thus making unreliable the measurement of serum testosterone as marker of total androgenic activity. The objective is to determine if serum androgen glucuronides can be replaced by testosterone or another steroid as measure of androgenic activity. Since the glucuronide derivatives of androgens are the obligatory route of elimination of all androgens, these metabolites were measured by liquid chromatography tandem mass spectrometry under basal conditions in 377 healthy postmenopausal women aged 55-65 years as well as in 47 premenopausal women aged 30-35 years while testosterone was assayed by gas chromatography mass spectrometry. No correlation was found between the serum concentration of testosterone and that of androsterone glucuronide (ADT-G) or androstenediol glucuronide (3␣-diol-G), the androgen metabolites which account for the total pool of androgens. The present data show that measurement of the total pool of androgens reflected by the serum levels of ADT-G and 3␣-diol-G cannot be replaced by serum testosterone or any other steroid, including DHEA or DHEA sulphate. These findings may have implications for women with androgen deficiency involving osteoporosis, obesity, type 2 diabetes, sexual dysfunction, loss of muscular strength and a series of other clinical situations affecting women's health. Measuring ADT-G and 3␣-diol-G might identify cases of true androgen deficiency and provide an opportunity to offer appropriate androgen therapy.
The Journal of Steroid Biochemistry and Molecular Biology, 2008
Healthy postmenopausal women aged 60-65 years (n = 150) were randomized to receive twice daily ap... more Healthy postmenopausal women aged 60-65 years (n = 150) were randomized to receive twice daily application on the skin of 3 g of a 0.3% dehydroepiandrosterone (DHEA) or placebo emulsion for 12 months. Serum DHEA and eleven of its metabolites were measured at screening and on day 1, as well as at 1, 3, 6, 9 and 12 months to study long-term metabolism. While serum DHEA and androst-5-ene-3, 17-diol (5-diol) increased by 203% and 178%, respectively, on average, during the 12-month period, the sum of concentrations of the metabolites of androgens, namely androsterone glucuronide (ADT-G), androstane-3␣,17-diol-3G and-17G increased by only 71% while usually non statistically significant changes of 30%, 17% and 20% were observed for estrone (E 1), estradiol (E 2) and E 1 sulfate (E 1-S), respectively. Despite the return of serum DHEA to normal premenopausal values with the present DHEA treatment regimen, the 65% decrease in the androgen pool found in this group of postmenopausal women is in fact corrected by only 24%, thus remaining 41% below the values found in normal premenopausal women. In fact, the changes in serum DHEA observed after percutaneous DHEA administration are a 186% overestimate of the true changes in androgen formation while the overestimate of estrogen production is even much higher. On the other hand, the pharmacokinetics of the steroids are stable over the 12-month period with no significant induction or decrease of activity of the enzymatic systems transforming DHEA predominantly into androgens.
The Journal of Steroid Biochemistry and Molecular Biology, 2013
In order to avoid the risks of non-physiological systemic exposure, serum concentrations of estra... more In order to avoid the risks of non-physiological systemic exposure, serum concentrations of estradiol (E 2) and testosterone (as measured by mass spectrometry-based assays) should remain below the 95th centiles measured at 9.3 pg/ml and 0.26 ng/ml for these respective sex steroids in normal postmenopausal women. To document the possibility of achieving this therapeutic objective, we have measured individual 24 h serum E 2 and testosterone concentrations in women with vulvovaginal atrophy (VVA) receiving daily intravaginal administration of a clinically effective dose of 6.5 mg prasterone (dehydroepiandrosterone, DHEA). Serum E 2 and testosterone, as well as DHEA and nine of its other metabolites, were assayed at ten time intervals over 24 h on the first and seventh days of daily vaginal administration of 6.5 mg prasterone. No significant change from baseline of average 24 h serum E 2 or testosterone concentrations was observed. Moreover, average 24 h serum DHEA remained within the normal postmenopausal range. Estrone sulfate and the androgen metabolites androsterone glucuronide and androstane-3␣, 17-diol glucuronide did not change, thus confirming the absence of any biologically relevant systemic exposure to estrogens and androgens, respectively. Serum concentrations of metabolites of both estrogens and androgens remain within the normal postmenopausal range following daily intravaginal administration of 6.5 mg prasterone. As other studies have shown, local formation of sex steroids in peripheral tissues without significant release of E 2 or testosterone in the circulation can be achieved with intravaginal prasterone. Thus, prasterone is a promising physiological and attractive solution to treating VVA symptoms.
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Papers by René Bérubé