Rates and product identification for trenbolone acetate metabolite biotransformation under aerobic conditions

Abstract

Trenbolone acetate metabolites are endocrine-active contaminants discharged into the aquatic environment in runoff from agricultural fields, rangelands, and concentrated animal feeding operations. To investigate the environmental fate of these compounds and their biotransformation mechanisms, the authors used inocula from a variety of different water sources and dosed biologically active microcosms with approximately 1400 ng/L of trenbolone acetate metabolites, including 17β-trenbolone, trendione, and 17α-trenbolone. To investigate aerobic biotransformation rates and interconversions between known trenbolone acetate metabolites, gas chromatography-tandem mass spectrometry was used to measure concentrations and assess product distributions as a function of time. High-resolution liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to characterize novel transformation products and potential transformation pathways. Kinetic analysis yields observed half-lives of approximately 0.9 d, 1.3 d, and 2.2 d for 17β-trenbolone, trendione, and 17α-trenbolone, respectively, at 20 °C, although colder conditions increased half-lives to 8.5 d and biphasic transformation was observed. Relative to reported faster attenuation rates in soils, trenbolone acetate metabolites are likely more persistent in aqueous systems. Product distributions indicate an enzymatic preference for biotransformation between trendione and 17β-trenbolone. The LC-MS/MS characterization indicates dehydrogenation products as the major detectable products and demonstrates that major structural elements responsible for bioactivity in steroids are likely retained during biotransformation.

Decoupling of a neutron interferometer from temperature gradients

“…Examples include the first observation of a quantum phase shift due to the Earth's gravitational field [4], demonstrating the 4π symmetry of spinor rotation [5], and measuring the effect of the Earth's rotation on the phase of the neutron (Sagnac effect) [6] among other fundamental experiments. In addition, neutron interferometry has been used for precision measurements of coherent and incoherent neutronnucleus scattering cross sections [7][8][9].…”

Effect of quantum statistics on the gravitational weak equivalence principle

“…Experimental probes into possibility of violation of the weak equivalence principle in quantum mechanics have been attempted using interference phenomenon associated with the gravitational potential in neutron and atomic interferometry experiments [7,8]. However, the phase shifts observed in such experiments [7] may be expressed in terms of directly observable quantities which turn out to be independent of mass [9], thus ruling out the violation in this context. Moreover, atomic interferometry experiments [8] need to be performed with different atomic species in order for a rigorous experimental test of the weak equivalence principle at the quantum level.…”

Coupled reversion and stream-hyporheic exchange processes increase environmental persistence of trenbolone metabolites

“…17a-TBOH represents about 95% of identifiable excreted metabolites by mass 4 , although a number of unidentified TBA metabolites likely exist. Given the typical application rates of TBA to cattle, mass balance calculations predict that thousands of ng l À 1 are possible in agricultural runoff 5,6 , although concentrations observed in receiving waters are typically far lower when detected 7,8 . Field observations have documented 1,700 ng l À 1 17a-TBOH in manure lagoons 9 , and 55 ± 22 ng g À 1 in solid manure and surface soils 10 .…”