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Native circulating oxytocin (OT) levels in non‐pregnant/non‐lactating/non‐medicated humans are very low (≤ 8 pg/mL). The lower limit of detection (LLOD) of our previous liquid chromatography mass spectrometry (LC–MS) method (10–25 pg/mL) precluded their quantification in serum and urine. Thus, we sought to improve the LC–MS sensitivity of OT measurements in these matrices by hydrophobic tagging and solid phase extraction (SPE). In the former approach, OT was reduced then alkylated with N‐alkyl acetamide (C12, C14, C16, and C18) tags or derivatized using sulfonyl chloride‐based reagents. In the latter approach, native OT in serum and urine was concentrated by offline SPE using gradient acetonitrile washings after first crashing with acetonitrile. Peak urinary eluate fractions were further concentrated online then analyzed by orbitrap‐based LC–MS with electrospray ionization. All hydrophobic OT derivatives had lower sensitivity than native OT. Washing with a water‐acetonitrile gradient during SPE improved the LLOD of OT in spiked serum to 2.5 pg/mL, while adding a subsequent online‐concentration step improved the LLOD in spiked urine to 1–5 pg/mL and allowed us to detect OT in urine from lactating women. We were unable to improve the sensitivity of OT measurements by hydrophobic tagging or by derivatization using sulfonyl chloride‐based reagents. However, we were successful in improving the sensitivity of native OT measurements in serum and urine 2‐ and 5‐fold, respectively, from our previous orbitrap‐based LC–MS method. Offline SPE was mandatory for both matrices and a subsequent online‐concentration step was required for urine. [ABSTRACT FROM AUTHOR]

Oxytocin (OT) is a neurohormone that has gained interest recently due to its emerging role in cognition and social/emotional behaviors, including possibly depression and autism. OT is commonly measured using enzyme‐ or radio‐based immunoassays (RIA, ELISA), which lack specificity or are complicated to perform and involve hazardous radioactive material. We have developed a high resolution accurate‐mass (HRAM) liquid chromatography–mass spectrometry (LC–MS) method that separates interferences and selectively and accurately quantitates native OT from human serum, urine, and saliva after solid phase extraction. The doubly protonated OT ion m/z 562.25503 was selected for quantitation due its high signal intensity. With our method lower limit of detection (LLOD) of 5–25 pg/mL, we measured native OT in serum from pregnant women (16–24 pg/mL) and rats (350 pg/mL), and in serum, urine, and saliva from a healthy male after intranasal (IN) OT application of 100 IU and 20 IU and from a healthy post‐menopausal female after IN OT application of 100 IU. Peak levels were detected in serum, urine, and saliva 15–30 minutes after each dose then decreased to below detection limits 1–2 hours thereafter. We were unable to detect native OT in serum from non‐pregnant/non‐lactating/non‐medicated women due to levels known to occur below 5 pg/mL. The fast elimination of OT we found is in excellent agreement with the pharmacokinetics of OT in other studies. The effects on the central nervous system occurring after IN OT administration remains to be determined. We developed a high resolution accurate‐mass liquid chromatography–mass spectrometry (LC–MS) method that separates interferences and selectively and accurately quantitates native OT from human serum, urine, and saliva after extraction. Native OT levels in cord plasma and serum/plasma from non‐pregnant/non‐lactating/non‐medicated subjects were < 10 pg/mL. Extremely high levels in saliva were found after intranasal OT administration of 20 IU and 100 IU. Peak levels were detected in serum, urine, and saliva 15–30 minutes after each dose then decreased to below detection limits 1–2 hours thereafter. [ABSTRACT FROM AUTHOR]

Approximately 600 million people worldwide practise the carcinogenic habit of betel nut/quid chewing. Carcinogenic N-nitroso compounds have been identified in saliva or urine of betel chewers and the betel alkaloid arecoline in hair from habitual betel quid chewers. However, the pharmacokinetic parameters of these compounds have been little explored. Assessment of betel use by biomarkers is urgently needed to evaluate the effectiveness of cessation programmes aimed at reducing betel consumption to decrease the burden of cancers in regions of high betel consumption. In the search for biomarkers of betel consumption, we measured by liquid chromatography-mass spectrometry (LC-MS) the appearance and disappearance of betel alkaloids ( characteristic for betel nuts), N-nitroso compounds, and chavibetol ( characteristic for Piper Betle leaves) in saliva (n=4), hair (n=2), and urine (n=1) of occasional betel nut/quid chewers. The betel alkaloids arecoline, guvacoline, guvacine, and arecaidine were detected in saliva of all four participants and peaked within the first 2 h post-chewing before returning to baseline levels after 8 h. Salivary chavibetol was detected in participants consuming Piper Betle leaves in their quid and peaked ~1 h post-chewing. Urinary arecoline, guvacoline, and arecaidine excretion paralleled saliva almost exactly while chavibetol glucuronide excretion paralleled salivary chavibetol. No betel nut related compounds were detected in the tested hair samples using various extraction methods. From these preliminary results, we conclude that betel exposure can only be followed on a short-term basis (≤8 h post-chewing) using the applied biomarkers from urine and saliva while the feasibility of using hair has yet to be validated. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Breast cancer is the most commonly diagnosed female cancer and the second leading cause of death in women in the US, including Hawaii. Accumulating evidence suggests that aminomethylphosphonic acid (AMPA), the primary metabolite of the herbicide glyphosate—a probable human carcinogen, may itself be carcinogenic. However, the relationship between urinary AMPA excretion and breast cancer risk in women is unknown. In this pilot study, we investigated the association between pre-diagnostic urinary AMPA excretion and breast cancer risk in a case-control study of 250 predominantly postmenopausal women: 124 cases and 126 healthy controls (individually matched on age, race/ethnicity, urine type, date of urine collection, and fasting status) nested within the Hawaii biospecimen subcohort of the Multiethnic Cohort. AMPA was detected in 90% of cases and 84% of controls. The geometric mean of urinary AMPA excretion was nearly 38% higher among cases vs. controls (0.087 vs 0.063 ng AMPA/mg creatinine) after adjusting for race/ethnicity, age and BMI. A 4.5-fold higher risk of developing breast cancer in the highest vs. lowest quintile of AMPA excretion was observed (OR Q5 vs. Q1 : 4.49; 95% CI: 1.46–13.77; p trend = 0.029). To our knowledge, this is the first study to prospectively examine associations between urinary AMPA excretion and breast cancer risk. Our preliminary findings suggest that AMPA exposure may be associated with increased breast cancer risk; however, these results require confirmation in a larger population to increase study power and permit careful examinations of race/ethnicity differences. Odds ratio of breast cancer as a function of quintiles of urinary aminomethylphosphonic acid excretion (Q1=lowest, Q5=highest quintiles). [Display omitted] • AMPA was detected in urine of 90% of cases, 84% of controls. • Breast cancer risk was 4.5-fold higher in the highest vs. the lowest AMPA quintile. • AMPA exposure may be associated with increased breast cancer risk. [ABSTRACT FROM AUTHOR]