Serum bisphenol a concentrations showed gender differences, possibly linked to androgen levels

To investigate human exposure to bisphenol A (BPA), a widely used endocrine disruptor, we measured serum BPA concentrations and analyzed the interrelation of BPA with sex-related hormones. BPA was detected in all human sera by a novel enzyme-linked immunosorbent assay. Serum BPA concentrations were significantly higher in normal men (1.49 +/- 0.11 ng/ml; P < 0.01) and in women with polycystic ovary syndrome (1.04 +/- 0.10 ng/ml; P < 0.05) compared with normal women (0.64 +/- 0.10 ng/ml). There were significant positive correlations between serum BPA and total testosterone (r = 0.595, P < 0.001) and free testosterone (r = 0.609, P < 0.001) concentrations in all subjects and likewise between serum BPA and total testosterone (r = 0.559, P < 0.01) and free testosterone (r = 0.598, P < 0.001) concentrations in all female subjects, but not between serum BPA and other sex-related hormone concentrations in any group. These findings showed that there are gender differences in serum BPA concentrations, possibly due to differences in the androgen-related metabolism of BPA.     

Gender differences in the levels of bisphenol A metabolites in urine

The metabolism of bisphenol A (BPA), a suspected endocrine disruptor, should be considered for monitoring human exposure to BPA, because the conjugation with beta-D-glucuronide and sulfate reduces the estrogenic activity. In this study, BPA levels in 30 healthy Koreans (men, N=15, 42.6+/-2.4 years; women, N=15, 43.0+/-2.7 years) were analyzed from urine treated with/without beta-glucuronidase and/or sulfatase by an RP-HPLC with fluorescence detection. The total BPA concentrations including free BPA and the urinary conjugates were similar in men and women (2.82+/-0.73 and 2.76+/-0.54 ng ml(-1), respectively), but gender differences were found in the levels of urinary BPA conjugates. Men had significantly higher levels of BPA-glucuronide (2.34+/-0.85 ng ml(-1)) than women (1.00+/-0.34 ng ml(-1)), whereas women had higher levels of BPA-sulfate (1.20+/-0.32 ng ml(-1)) than men (0.49+/-0.27 ng ml(-1)).     

Gender difference in serum bisphenol A levels may be caused by liver UDP-glucuronosyltransferase activity in rats

Gender difference in human bisphenol A (BPA) concentrations was revealed by determining serum BPA. We studied the serum concentrations and the metabolism of BPA in rats by an HPLC system. Rat serum BPA concentrations were significantly higher in males (24.9+/-7.38 ng/ml, P=0.026, n=10) than in females (8.27+/-3.11 ng/ml, n=10), as in humans. The resultant enzyme reaction products of BPA glucuronidation in the rat liver microsomes fraction were analyzed by an HPLC system. The ratio of BPA glucuronidation in the microsome reaction was significantly higher (P=0.015) in female than in male rats. The mRNA expression of UDP-glucuronosyltransferase 2B1 (UGT2B1), an isoform of UGT related to BPA glucuronidation, in the rat liver was analyzed by a real-time quantitative RT-PCR. The relative expression level of UGT2B1 mRNA was significantly higher (P<0.001) in female than in male rat livers. The gender difference in serum BPA concentrations may be explained by the difference in clearance based on the UGT activities.     

Inhibition by wheat sprout (Triticum aestivum) juice of bisphenol A-induced oxidative stress in young women

For health of future generation, fertile young women should be monitored for exposure of endocrine disrupting chemicals (EDCs). Among EDCs, bisphenol A (BPA) is suggested to induce reactive oxygen species (ROS) which play an important role in pathologies of female diseases such as endometriosis. On the other hand, previous studies suggested that sprouts of wheat (Triticum aestivum) have antimutagenicity and antioxidant activity. We performed the 2 weeks intervention of wheat sprout juice (100ml/day) to investigate its effects on BPA-exposure and -oxidative toxicity in young women (N=14, age=24.4±4.0). Geometrical mean of urinary BPA levels was 1.81 (GSTD, 4.34)μg/g creatinine. We observed that irregular meals significantly increased levels of urinary BPA approximate 3 times (p=0.03). In addition, we found BPA-induced oxidative stress is correlated with levels of 8-hydroxydeoxyguanosine (8-OHdG) or malondialdehyde (MDA) levels (p=0.18 or 0.03, respectively). We also observed a continuous reduction of urinary BPA during the wheat sprout intervention (p=0.02). In summary, our data suggested potential detoxification of wheat sprouts on BPA-toxicity via antioxidative and interference of absorption, distribution, metabolism and excretion (ADME)-mediated mechanisms in young women.     

Amniotic fluid cathelicidin in PPROM pregnancies: from proteomic discovery to assessing its potential in inflammatory complications diagnosis

Background

Preterm prelabor rupture of membranes (PPROM) complicated by microbial invasion of the amniotic cavity (MIAC) leading to histological chorioamnionitis (HCA) significantly impacts perinatal morbidity. Unfortunately, no well-established tool for identifying PPROM patients threatened by these disorders is available.

Methodology/Principal Findings

We performed an unbiased exploratory analysis of amniotic fluid proteome changes due to MIAC and HCA. From among the top five proteins that showed the most profound and significant change, we sought to confirm results concerning cathelicidin ({"type":"entrez-protein","attrs":{"text":"P49913","term_id":"1706745","term_text":"P49913"}}P49913, CAMP_HUMAN), since an ELISA kit was readily available for this protein. In our exploratory proteomic study, cathelicidin showed a ∼6-fold higher concentration in PPROM patients with confirmed MIAC and HCA. We verified significantly higher levels of cathelicidin in exploratory samples (women without both MIAC and HCA: median 1.4 ng/ml; women with both conditions confirmed: median 3.6 ng/ml; p = 0.0003). A prospective replication cohort was used for independent validation and for assessment of cathelicidin potential to stratify women with MIAC leading to HCA from women in whom at least one of these conditions was ruled out. We confirmed the association of higher amniotic fluid cathelicidin levels with MIAC leading to HCA (the presence of both MIAC and HCA: median 3.1 ng/ml; other women: median 1.4 ng/ml; p<0.0001). A cathelicidin concentration of 4.0 ng/ml was found to be the best cut-off point for identifying PPROM women with both MIAC and HCA. When tested on the validation cohort, a sensitivity of 48%, a specificity of 90%, a likelihood ratio of 5.0, and an area under receiver-operating characteristic curve of 71% were achieved for identification of women with MIAC leading to HCA.

Conclusions

Our multi-stage study suggests cathelicidin as a candidate marker that should be considered for a panel of amniotic fluid proteins permitting identification of PPROM women with MIAC leading to HCA.     

Twice single doses of 100,000 IU of vitamin D in winter is adequate and safe for prevention of vitamin D deficiency in healthy children from Ushuaia, Tierra Del Fuego, Argentina

In order to improve vitamin D status of children from Ushuaia (55°S), at the South of Argentina, double supplementation with 100.000 IU of vitamin D was administered at the beginning of winter (March 2004), and 3 months later during winter (June 2004). In 2004, serum 25-hydroxyvitamin D (25OHD) was measured before the first supplementation, a month after, and 3 months after receiving the second supplementation (March, April and September). We studied 18 healthy children from Ushuaia, age (mean ± S.D.) 7.3 ± 4.4 years old (range 1.2–14.6), seven girls and 11 boys. Before treatment, serum 25OHD was 29.3 ± 5.9 ng/ml. It increased significantly 1 month after the first supplementation (April): 35.3 ± 4.4 ng/ml (p < 0.001), and decreased significantly 3 months after the second supplementation: 22.4 ± 4.6 ng/ml (September (p < 0.001). No child was neither deficient (<10 ng/ml) nor insufficient (10–15 ng/ml) of vitamin D. On April, a month after the first supplementation, no children had vitamin D intoxication levels (>50 ng/ml). These results disclosed that to prevent vitamin D deficiency for children at zones of risk at the south of our country, double supplementation of 100,000 IU of vitamin D during autumn and winter, would be adequate and safe.     

Metabolic activation of benzo(a)pyrene by human amniotic fluid

The in vitro activation of benzo(a)pyrene was studied in amniotic fluid from ten 4-month pregnant women. Benzo(a)pyrene monooxygenase and epoxide hydrolase activities were in the same range in amniotic fluid as in human liver. Glutathione epoxide transferase activity was markedly lower than in hepatocytes. Human amniotic fluid also catalyzed the formation of hydrocarbon metabolites mutagenic to Salmonella typhimurium TA98 (Ames system). Profiles of amniotic fluid aromatic hydrocarbons from non smokers exhibited low benzo(a)pyrene concentration (less than 0.1 ng/ml).     

Falls are associated with decreased renal function and insufficient calcitriol production by the kidney

In a double blind placebo controlled 3-year osteoporosis study in elderly women, we collected prospective data on falls. The study population comprised 489 normal elderly women aged 65–77 years randomized to four groups: placebo, calcitriol 0.25 mcg b.i.d., conjugated equine estrogens (0.625 mg/day) and calcitriol + estrogen. Falls occurred in 57% of all women.

Using a Poisson regression model, the placebo group with low GFR-creatinine clearance (CrCl < 60 ml/min) had 60% more falls compared to the group with CrCl ≥ 60 ml/min. Further sub group analyses showed that there is no increased risk of falls with CrCl 60–70, 70–80 and >90 ml/min. Calcitriol treatment significantly reduced the number of falls by 50% (OR = 0.5, 95% CI: 0.4–0.9, p = 0.010) compared to placebo in the low CrCl group.

The group with lower CrCl had lower calcium absorption (p < 0.001), lower serum 1,25-dihydroxyvitamin D (1,25(OH)₂D) (p < 0.001) and normal serum 25OHD suggesting that there is decreased conversion of 25OHD to 1,25(OH)₂D by the aging kidney. It is postulated that the decrease in falls on calcitriol therapy is related to an increase in serum 1,25(OH)₂D, upregulation of VDR and improvement in muscle strength although one cannot exclude an effect on the central nervous system.     

Age-related changes in 11β-hydroxyandrostenedione concentration in normal and osteoporotic women

The secretion of dehydroepiandrosterone (DHEA) and its sulfate is known to decline gradually with advancing age. Furthermore DHEA is known to be significantly lower in osteoporotic subjects than in normals. Recently 11β-hydroxyandrostenedione (11-OHA) has been proposed as an important indicator of the adrenal source of hormone excess in different hyperandrogenic states. In the present study we measured 11-OHA in 224 normal women aged 20–79 yr and 130 osteoporotic women aged 40–79 yr. RIA of 11-OHA was performed with highly specific antiserum raised in rabbits.

The mean 11-OHA serum concentration was 2.20±0.90 ng/ml in normal women and 1.75±0.58 ng/ml in osteoporotic women. In contrast to DHEA there was no age-related decrease in 11-OHA serum concentrations in normal and osteoporotic women. Osteoporotic subjects showed statistically significantly lower 11-OHA serum concentrations than normal women. Therefore low serum 11-OHA might represent a further risk factor for osteoporosis.     

The effect of follicle-stimulating hormone on follicular development, granulosa cell apoptosis and steroidogenesis and its mediation by insulin-like growth factor-I in the goat ovary

The effect of FSH on goat follicular development, granulosa cell apoptosis and steroidogenesis and its mediation by insulin-like growth factor (IGF)-I were studied through both in vivo and in vitro experiments. The FSH treatment was begun on Day 9 after estrus and consisted of injections twice a day for 3 days in decreasing doses (7.5–7.5–5.0–5.0–2.5–2.5 mg). Does in both treatment and control groups were slaughtered for ovaries on Day 12. Granulosa cell apoptosis was detected by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL). Expression of IGF-I and IGF-II mRNA was determined by RT–PCR, while concentrations of progesterone (P4), estradiol (E2), IGF-I and IGF-II were measured by radioimmunoassay (RIA). Following parameters increased significantly (P<0.05) after the FSH treatment: follicle number (5.0±1.5 versus 9.0±2.0 per ovary), the level of E2 (0.1±0.1 ng/ml versus 0.7±0.2 ng/ml), the E2/P4 ratio (0.7±0.4 versus 4.7±3.0) and the concentrations of IGF-I (0.5±0.2 ng/ml versus 119.4±15.1 ng/ml) and IGF-II (0.12±0.03 ng/ml versus 40.9±18.7 ng/ml) in follicular fluid of the medium sized (3–5 mm) follicles and in the ovarian cortex the relative quantity of IGF-I mRNA (0.37±0.17 versus 0.90±0.12 Max OD). In contrast, the ratio of apoptotic granulosa cells in these follicles was reduced significantly (0.53±0.1 versus 0.10±0.01, P<0.05). In large (>5 mm) follicles, however, only the follicle number (2.3±0.7 versus 7.0±1.5 per ovary) and the level of IGF-I (38.4±11.0 ng/ml versus 87.3±13.9 ng/ml) increased significantly (P<0.05), whereas other values did not change. In vitro culture of granulosa cells showed that FSH significantly (P<0.05) enhanced IGF-I production (12.7±2.1 ng/ml versus 26.±21.9 ng/ml) by these cells, and both FSH and IGF-I reduced the ratios of apoptotic cells (from 0.7±0.07 to 0.3±0.1 and 0.2±0.04, respectively) and the effect was additive when both were used together. H89, the PKA pathway inhibitor, blocked the effect of FSH on granulosa cell apoptosis and IGF-I production in vitro. These results indicated that FSH mainly enhanced the development of medium sized follicles in the goat by suppressing the apoptosis of granulosa cells via increasing production of IGF-I and steroids, possibly through the PKA pathway.     

Extrapolation of Rodent Studies on Amniotic Fluid Contaminatnts to Human Populations

If endocrine active chemicals (EACs) adversely affect human development, then there must be evidence of effects in animal models at properly scaled levels of exposure during pertinent sensitive periods as derived from quantified exposures of the human fetus. Our recent studies attempt to address both effects and exposures. First Study: Dams were gavaged from Gestation Day (GD) 14 through weaning on Post-Natal Day (PND) 21 with either corn oil alone (unexposed controls) or Low DES (0.5?mg/kg BW); High DES (5.0?mg/kg BW); GEN (15?mg/kg BW); GEN + DES (GEN at 15?mg/kg BW and DES at 0.5?mg/kg BW). No treatments affected duration of gestation, litter size or birth anogenital distance / birth body weights ((bAGD/bBW) or ratios of bAGD/cube root of bBW of pups of either sex. The ratio of weaning AGD to weaning body weight (wAGD/wBW) differed significantly between the control group and each of the estrogenic treatments in both sexes with larger wAGD/wBW values associated with each of the estrogenic treatments. Males exposed to High DES and GEN alone exhibited earlier onset of puberty. Only females in the low DES group showed an earlier onset of puberty. At 50 to 70 days of age, the ratios of male reproductive organ weights/body weight were unaffected by estrogen treatment in all groups except high DES which increased testicle weight and decreased epididymis, seminal vesicle, and prostate weights. Initial vaginal cycle lengths were affected only in the high DES group. Thus low doses of DES and GEN at levels comparable to the upper range of human exposure affect some but not all markers of sexual development. Second Study: Amniotic fluid samples obtained at routine amniocentesis between 15 and 23 weeks of gestation were assayed by gas chromatographic/mass spectrometric (GC/MS) analysis. The first group of amniotic fluid samples (n = 53) from 51 women were analysed for several xenobiotic EACs. Alpha-hexachlorocyclohexane, with a mean (± SD) concentration of 0.15 ± 0.06 (ng/ml), and p,p′-DDE, with a mean (± SD) concentration of 0.21 ± 0.18?ng/ ml, were detected in several specimens. Overall one in three amniotic fluid samples tested positive for at least one xenobiotic EAC. Another group of amniotic fluid samples (n = 62) from 56 women were analysed for phytoestrogenic EACs. The mean (± SD) concentration of daidzein and genistein in amniotic fluid were 1.14 ± 1.04 and 1.37 ± 1.00?ng/ml with maximum levels of 5.52 and 4.86?ng/ml, respectively. Overall, 26 and 34 of the samples had quantifiable levels of daidzein and genistein, respectively. Conclusions: One in three human fetuses were exposed to xenobiotic EACs and two of three human fetuses were exposed to phytoestrogenic EACs in utero. Our demonstrations that EACs have developmental effects in an animal model at levels of exposure that mimic those found in humans in North America during sensitive time-frames sustains concerns about potential adverse health effects of developmental exposures to EACs for the human fetus/neonate.     

Amniotic fluid concentration of 5-hydroxyeicosatetraenoic acid is increased in human parturition at term

5-hydroxyeicosatetraenoic acid (5-HETE) is an arachidonate lipoxygenase product capable of stimulating uterine contractility in a dose-dependent manner in vitro. The purpose of this study was to determine if spontaneous human labor at term is associated with changes in the concentration of this metabolite in amniotic fluid. Fluid was retrieved from 36 women not in labor and from 30 women in active labor at term. 5-HETE was determined by radioimmunoassay. The median amniotic fluid concentration of 5-HETE of women in labor was significantly greater than that of women not in labor (3538 pg/ml vs. 1977 pg/ml, respectively; p = 0.05). This observation is consistent with activation of the lipoxygenase pathway of arachidonic acid metabolism during spontaneous human parturition at term.     

Radioimmunoassay of 17-hydroxyprogesterone

A method is described for the determination of 17-hydroxyprogesterone in peripheral venous plasma (0.1–1.0 ml) from men and women using an antiserum to 17-hydroxyprogesterone-3-carboxymethyl oxime bovine serum albumin (BSA).

The coefficients of variation on replicate analyses ranged from 7–16%. The louest level of 17-hydroxy-progesterone uhich may be determined is 5 ng/100 ml plasma. The concentration (mean ± S.D.; ng/100 ml plasma) in a group of healthy men (aged 20–40 yrs) uas 123 ± 65. From women during days 1–10 of the menstrual cycle the value uas 40 ± 15, during days 18–32 of the cycle 134 ± 57 and during pregnancy (12th week to term) 622 ± 262. Progesterone was determined in the same samples using an antiserum to 11-hydroxyprogesterone-11-hemisuccinate-BSA.     

What is an endocrine disruptor?

Endocrine disrupting chemicals (EDCs) and potential EDCs are mostly man-made found in various materials. By interfering with the body's endocrine system, endocrine disruptors produce adverse developmental, reproductive, neurological, and immune effects in humans, abnormal growth patterns and neurodevelopmental delays in children. Thus, diethylstilbestrol (DES) a non-steroidal estrogen, which is regarded as a proof of concept, induces clear cell carcinoma among young women. EDCS may be found in plastic bottles and metal food cans (BPA), medical devices (phthalates), detergents, flame retardants (polybrominated diphenyl ethers), food (BPA), toys (phthalates), cosmetics and drugs (parabens), and pesticides (alkyl phenols such as nonylphenol). The deleterious effects of endocrine disruptors constitute a real public health issue. However concerning the mechanisms of action of EDCs, many questions remain unanswered and need further investigations.     

Quantitation of trimipramine enantiomers in human serum by enantioselective high-performance liquid chromatography and mixed-mode disc solid-phase extraction

A sensitive and stereospecific method for the quantitation of trimipramine enantiomers in human serum was developed. The assay involves the use of a novel mixed-mode disc solid-phase extraction for serum sample clean-up prior to HPLC analysis and is also free of interference from the enantiomers of desmethyltrimipramine, 2-hydroxytrimipramine, and 2-hydroxydesmethyltrimipramine, the three major metabolites of trimipramine. Chromatographic resolution of trimipramine enantiomers was performed on a reversed-phase cellulose-based chiral column (Chiralcel OD-R) under isocratic conditions using a mobile phase consisting of 0.3 M aqueous sodium perchlorate-acetonitrile (58:42, v/v) at a flow-rate of 0.5 ml/min. Recoveries for R- and S-trimipramine enantiomers were in the range of 93–96% at 25–185 ng/ml levels. Intra-day and inter-day precisions calculated as R.S.D. were in the ranges of 0.30-8.00% and 1.60-10.20% for both enantiomers, respectively. Intra-day and inter-day accuracies calculated as percent error were in the 0.01–2.10% and 1.00–3.00% ranges for both enantiomers, respectively. Linear calibration curves were in the concentration range 15–250 ng/ml for each enantiomer in serum. The limit of quantification of each enantiomer was 15 ng/ml. The detection limit for each enantiomer in serum using a UV detector set at 210 nm was 10 ng/ml (S/N =2). In addition, separation of the enantiomers of desmethyltrimipramine, 2-hydroxytrimipramine, and 2-hydroxydesmethyltrimipramine were investigated. The desmethyltrimipramine enantiomers could be resolved on the Chiralcel OD-R column under the same chromatographic conditions as the trimipramine enantiomers, but the other two metabolite enantiomers required different mobile phases on the Chiralcel OD-R column to achieve satisfactory resolution with R_s values of 1.00.     

High-performance liquid chromatographic analysis of melatonin in human plasma and rabbit serum with on-line column enrichment

This paper describes the development of a simple and sensitive analytical method for the quantification of melatonin in human plasma and rabbit serum, using standard analytical equipment and on-line column enrichment without prior extraction, clean-up or derivatization. The analytical procedure was found to be accurate, precise and linear. For human plasma, the accuracy was 101% (range 89–106%), and the mean precision was 5% (range 2–9%) for all concentrations (0, 2, 10, 50 and 200 ng/ml) tested (n=6). The accuracy in rabbit serum was 101% (range 90–112%), and the mean precision was 13% (range 8–19%) for all concentrations (0, 2, 10, 50, 200 and 500 ng/ml) tested (n=6). The retention time of melatonin was about 8 min and the total recoveries were found to be approximately 65 and 85%, respectively, for human plasma and rabbit serum. The limit of detection was found to be lower than 1 ng/ml for human plasma and around 2 ng/ml for rabbit serum. The method is, therefore, found to be suitable for melatonin bioavailability studies in rabbits and presumably also in humans.     

A simple two-step purification of human and monkey alpha fetoprotein from amniotic fluid and serum.

We developed a two-step purification system to characterize alpha fetoprotein (AFP) in early gestation amniotic fluid and late gestation fetal serum or cord blood from monkey and human. It involves only two chromatographic steps, allows preparative purification using up to 12 ml of starting sample, can purify up to 350 micrograms of AFP at one time, and can be used to purify both fetal serum or amniotic fluid AFP from two different species. This procedure will allow detailed biochemical analysis of purified AFP from different stages of fetal development.     

Oncostatin M and its receptor in women with polycystic ovary syndrome and association with assisted reproductive technology outcomes

The role of adipokines in ovarian-related disorders such as polycystic ovary syndrome (PCOS) has been reported. However, the involvement of Oncostatin M (OSM), a recently identified adipokine, in ovarian function is unknown. Therefore, we investigated the association of the OSM signaling pathway with ovarian functions and PCOS pathogenesis. This case-control study enrolled 30 PCOS and 30 healthy women who underwent the intracytoplasmic sperm injection procedure. OSM and OSM receptor (OSMR) levels were evaluated in the follicular fluid (FF). Moreover, the expression of insulin receptor substrates (IRS1 and IRS2), OSM, OSMR, suppressor of cytokine signaling 3 (SOCS3), and androgen receptor (AR) genes were analyzed in the isolated cumulus cells (CCs). For the in-vitro experiment, the effect of recombinant OSM on the expression of related genes in isolated CCs was analyzed. Follicular concentrations of OSM and OSMR were significantly lower in PCOS (123.91±48.58 pg/ml and 0.93±0.35 ng/ml, respectively) compared to control women (283.53 ± 96.62 pg/ml and 1.45 ± 0.18 ng/ml, respectively; p < 0.001) and were positively correlated with the oocyte maturation (r = 0.611 and r = 0.611, respectively) and fertilization (r = 0.592 and r = 0.627, respectively) rates in the PCOS group. Furthermore, the SOCS3 expression was upregulated about eight times in PCOS patients compared to the controls (p < 0.05). The treatment of cells with recombinant OSM significantly increased SOCS3, OSMR, IRS-1, and -2 expression and decreased AR expression. The decreased levels of OSM and its receptor in PCOS patients, possibly mediated by SOCS3, could negatively affect oocyte maturation and fertilization rates.     

Stereoselective determination of mepivacaine in human serum using a brush-type chiral stationary phase and solid-phase extraction

A stereoselective high-performance liquid chromatography assay method was developed for the quantitation of R-(+)- and S_-(−)-mepivacaine in human serum. The assay uses a Pirkle brush-type. ((S)-tert.-leucine, (R)-(-naphthyl)ethylamine stationary phase (Sumichiral OA-4700, 250×4 mm I.D.) at ambient temperature with a mobile phase of hexane-ethylenedichloride-absolutte methanol (85:10:5, v/v) for the separation of R-(+) and (S)-(−)-mepivacaine. The eluents were monitored using UV detection at 220 nm. Isolation of the analytes from serum was performed using a 1-ml C₁₈ solid-phase extraction cartridge with high recovery and selectivity. The detection limits were 100 ng/ml for each enantiomer and the limits of quantitation were 150 ng/ml for both enantiomers. Linear calibration curves in the 150–2400 ng/ml range showed good correlation coefficients (r>0.9994, N=3). Precision and accuracy of the method were within 2.1–5.3 and 2.0–3.6%, respectively, for (R)-(+)-mepivacaine and 2.7–5.7% and 1.7–4.2%, respectively, for S-(−)-mepivacaine.