Effects of Mixed Pasture Legume Phytoestrogens on Superovulatory Response and Embryo Quality in Angus Cows.

Ovulation and artificial insemination rates have been observed to decrease in sheep and cows when exposed to dietary phytoestrogens at concentrations greater than 25 mg/kg DM. A grazing trial was undertaken to investigate the effects of coumestrol and other key phytoestrogens on the superovulatory response, embryo numbers and quality in beef cows grazing legume pastures. A 7-week controlled grazing trial was conducted with legume and ryegrass pasture treatments, with cows exposed to legumes at two timed treatments, 4 and 7 weeks. Twenty Angus cows were subjected to a conventional estrus synchronization and superovulation protocol. Embryos were recovered via conventional uterine body flushing 7 days post artificial insemination (AI). Numerous phytoestrogens were identified in both pasture and plasma samples, including coumestrol and formononetin. Concentrations of phytoestrogens in the pasture ranged from 0.001 to 47.5 mg/kg DM and 0 to 2.6 ng/mL in plasma. Approximately 50% of cows produced viable embryos 7 days post AI. A significant interaction between the effect of treatment groups on the embryo stage was observed (p < 0.05). The results suggest that concentrations of >25 mg/kg DM of phytoestrogens less than 20 days preceding AI may negatively affect oocyte developmental competence, reduce progesterone production and thus contribute to early embryonic loss.

Phytoestrogens: A Review of Their Impacts on Reproductive Physiology and Other Effects upon Grazing Livestock.

Legume crops and pastures have a high economic value in Australia. However, legume species commonly used for grazing enterprises have been identified to produce high concentrations of phytoestrogens. These compounds are heterocyclic phenolic, and are similar in structure to the mammalian estrogen, 17ß-estradiol. The biological activity of the various phytoestrogen types; isoflavones, lignans and coumestans, are species-specific, although at concentrations of 25 mg/kg of dry matter each of the phytoestrogen types affect reproductive functions in grazing livestock. The impacts upon fertility in grazing livestock such as cattle and sheep, vary greatly over length of exposure time, age and health of animal and the stress stimuli the plant is exposed to. More recently, research into the other effects that phytoestrogens may have upon metabolism, immune capacity and growth and performance of grazing livestock has been conducted. Potential new benefits for using these phytoestrogens, such as daidzein and genistein, have been identified by observing the stimulation of production in lymphocytes and other antibody cells. Numerous isoflavones have also been recognized to promote protein synthesis, increase the lean meat ratio, and increase weight gain in cattle and sheep. In Australia, the high economic value of legumes as pasture crops in sheep and cattle production enterprises requires proactive management strategies to mitigate risk associated with potential loss of fertility associated with inclusion of pasture legumes as forages for grazing livestock.

Hyperpolarization of Amino Acids in Water Utilizing Parahydrogen on a Rhodium Nanocatalyst.

NMR offers many possibilities in chemical analysis, structural investigations, and medical diagnostics. Although it is broadly used, one of NMR spectroscopies main drawbacks is low sensitivity. Hyperpolarization techniques enhance NMR signals by more than four orders of magnitude allowing the design of new contrast agents. Parahydrogen induced polarization that utilizes the para-hydrogen's singlet state to create enhanced signals is of particular interest since it allows to produce molecular imaging agents within seconds. Herein, we present a strategy for signal enhancement of the carbonyl 13 C in amino acids by using parahydrogen, as demonstrated for glycine and alanine. Importantly, the hyperpolarization step is carried out in water and chemically unmodified canonical amino acids are obtained. Our approach thus offers a high degree of biocompatibility, which is crucial for further application. The rapid sample hyperpolarization (within seconds) may enable the continuous production of biologically useful probes, such as metabolic contrast agents or probes for structural biology.

Nuclear Spin Singlet States in Photoactive Molecules: From Fluorescence/NMR Bimodality to a Bimolecular Switch for Spin Singlet States.

Nuclear spin singlet states are silent states in nuclear magnetic resonance (NMR). However, they can be probed indirectly and offer great potential for the development of contrast agents for magnetic resonance imaging (MRI). Introduced here are two novel concepts: Firstly, the bimodal NMR/fluorescence properties of 13 C2 -tetraphenylethylene. It possesses a long-lived singlet state in organic solvents, and it shortens upon the addition of water. This simultaneously increases the aggregation-induced emission (AIE) of the molecule, resulting in a substantial enhancement of fluorescence. Secondly, introduced is a bimolecular switch for singlet states based on 3-2 H-coumarin containing an isolated proton. Upon UV-light exposure, a dimer forms, leading to a coupling between two previously isolated protons. A nuclear spin singlet state can now be populated. Excitation with a wavelength of 254 nm results in partial ring cleavage of the molecule back to its monomer.

More Than 12 % Polarization and 20†Minute Lifetime of 15 N in a Choline Derivative Utilizing Parahydrogen and a Rhodium Nanocatalyst in Water.

Hyperpolarization techniques are key to extending the capabilities of MRI for the investigation of structural, functional and metabolic processes in vivo. Recent heterogeneous catalyst development has produced high polarization in water using parahydrogen with biologically relevant contrast agents. A heterogeneous ligand-stabilized Rh catalyst is introduced that is capable of achieving 15 N polarization of 12.2±2.7 % by hydrogenation of neurine into a choline derivative. This is the highest 15 N polarization of any parahydrogen method in water to date. Notably, this was performed using a deuterated quaternary amine with an exceptionally long spin-lattice relaxation time (T1 ) of 21.0±0.4 min. These results open the door to the possibility of 15 N in vivo imaging using nontoxic similar model systems because of the biocompatibility of the production media and the stability of the heterogeneous catalyst using parahydrogen-induced polarization (PHIP) as the hyperpolarization method.

Effects of Cd vacancies and unconventional spin dynamics in the Dirac semimetal Cd3As2.

Cd3As2 is a Dirac semimetal that is a 3D analog of graphene. We investigated the local structure and nuclear-spin dynamics in Cd3As2 via 113Cd NMR. The wideline spectrum of the static sample at 295 K is asymmetric and its features are well described by a two-site model with the shielding parameters extracted via Herzfeld-Berger analysis of the magic-angle spinning spectrum. Surprisingly, the 113Cd spin-lattice relaxation time (T1) is extremely long (T1 = 95 s at 295 K), in stark contrast to conductors and the effects of native defects upon semiconductors; but it is similar to that of 13C in graphene (T1 = 110 s). The temperature dependence of 1/T1 revealed a complex bipartite mechanism that included a T2 power-law behavior below 330 K and a thermally activated process above 330 K. In the high-temperature regime, the Arrhenius behavior is consistent with a field-dependent Cd atomic hopping relaxation process. At low temperatures, a T2 behavior consistent with a spin-1/2 Raman-like process provides evidence of a time-dependent spin-rotation magnetic field caused by angular oscillations of internuclear vectors due to lattice vibrations. The observed mechanism does not conform to the conventional two-band model of semimetals, but is instead closer to a mechanism observed in high-Z element ionic solids with large magnetorotation constant [A. J. Vega et al., Phys. Rev. B 74, 214420 (2006)].

Aqueous Ligand-Stabilized Palladium Nanoparticle Catalysts for Parahydrogen-Induced 13C Hyperpolarization.

Parahydrogen-induced polarization (PHIP) is a method for enhancing NMR sensitivity. The pairwise addition of parahydrogen in aqueous media by heterogeneous catalysts can lead to applications in chemical and biological systems. Polarization enhancement can be transferred from 1H to 13C for longer lifetimes by using zero field cycling. In this work, water-dispersible N-acetylcysteine- and l-cysteine-stabilized palladium nanoparticles are introduced, and carbon polarizations up to 2 orders of magnitude higher than in previous aqueous heterogeneous PHIP systems are presented. P13C values of 1.2 and 0.2% are achieved for the formation of hydroxyethyl propionate from hydroxyethyl acrylate and ethyl acetate from vinyl acetate, respectively. Both nanoparticle systems are easily synthesized in open air, and TEM indicates an average size of 2.4 ± 0.6 nm for NAC@Pd and 2.5 ± 0.8 nm for LCys@Pd nanoparticles with 40 and 25% ligand coverage determined by thermogravimetric analysis, respectively. As a step toward biological relevance, results are presented for the unprotected amino acid allylglycine upon aqueous hydrogenation of propargylglycine.

A nanoparticle catalyst for heterogeneous phase para-hydrogen-induced polarization in water.

Para-hydrogen-induced polarization (PHIP) is a technique capable of producing spin polarization at a magnitude far greater than state-of-the-art magnets. A significant application of PHIP is to generate contrast agents for biomedical imaging. Clinically viable and effective contrast agents not only require high levels of polarization but heterogeneous catalysts that can be used in water to eliminate the toxicity impact. Herein, we demonstrate the use of Pt nanoparticles capped with glutathione to induce heterogeneous PHIP in water. The ligand-inhibited surface diffusion on the nanoparticles resulted in a (1) H polarization of P=0.25% for hydroxyethyl propionate, a known contrast agent for magnetic resonance angiography. Transferring the (1) H polarization to a (13) C nucleus using a para-hydrogen polarizer yielded a polarization of 0.013%. The nuclear-spin polarizations achieved in these experiments are the first reported to date involving heterogeneous reactions in water.