The Pragmatic Strategy to Detect Endocrine-Disrupting Activity of Xenobiotics in Food

Endocrine-disrupting activity induced by xenobiotics might pose a possible health threat. Facing so many chemicals, there is an issue on how we detect them precisely and effectively. The whole embryo culture (WEC) test, an ex vivo exposure lasting 48 hours with rat embryos of 10.5 days old, is used to detect prenatal developmental toxicity. We extended the WEC function to detect the endocrine-disrupting activity induced by environmental chemicals. Results showed that in the development of rat embryo, basically 17ß-estradiol, triiodothyronine, triadimefon, penconazole, and propiconazole exhibited no significant effect on yolk sac circulatory system, allantois, flexion, heart caudal neural tube, hindbrain, midbrain, forebrain, otic system, optic system, olfactory system, maxillary process, forelimb, hind limb, yolk sac diameter, crown-rump length, head length, and developmental score. In the immunohistochemistry, the positive control of 17ß-estradiol showed positive effect for its receptor expressions. These three triazoles induced expressions of ERα and ERß in WEC. This result basically meets the mode of action that triazoles were designed to disrupt the synthesis of steroid hormone. Here we gave a strategy to detect possible endocrine-disrupting activity induced by xenobiotics in food. This strategy is quick to initiate the whole rat embryo culture with 10.5 days to detect the hormone receptors such as androgen, estrogen, thyroid, aromatase activity and its related receptors

Deltamethrin Alters Thyroid Hormones and Delays Pubertal Development in Male and Female Rats

Pyrethroid insecticides are suspected endocrine-disrupting chemicals. Deltamethrin has been reported to antagonize thyroid hormone receptor activity in a reporter assay. We hypothesized that deltamethrin alters thyroid function. Male and female rats were administered daily oral gavages with 0, 0.3, 1, or 3 mg/kg/day deltamethrin on postnatal days 23–53 and 22–42, respectively. Results showed that deltamethrin decreased the relative thyroid weight in 0.3 and 1 mg/kg/day in female but not in male rats. Although the histology and several parameters of thyroid were not affected, the decreased relative weight exhibited underlying meaning. Deltamethrin delayed the age of vaginal opening (VO) and increased body weight upon VO in 3 mg/kg/day. Deltamethrin failed to delay the age of preputial separation in male rats. In the respective of serum hormone concentration, deltamethrin increased 17β-estradiol (E2) with dose-dependent manner in female rats. The novel finding is that deltamethrin decreased thyroxine (T4), triiodothyronine (T3), and thyroid-stimulating hormone (TSH) in the female rats. In contrast, deltamethrin increased T3 and TSH but not in T4 in male rats. We inferred that deltamethrin disrupts thyroid hormone and might be related to estrogen receptor agonist. The future work is to investigate if deltamethrin disrupts the hypothalamus-pituitary-thyroid axis

General dynamical equations of motion for elastic body systems

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76290/1/AIAA-11407-643.pd

The dynamical modelling of elastic multibody systems.

A modelling technique is presented for determining the time response of a system of bodies (rigid or flexible) which undergo large elastic deformations, coupled with large nonsteady translational and rotational motions. The derivations of the governing equations of motion are based on Lagrange's form of d'Alembert's principle. The general dynamical equations of motion are expressed in terms of stress and strain tensors, kinematic variables, the velocity and angular velocity coefficients, and generalized forces. These equations are derived systematically. The formulation of the general dynamical equations of motion are discussed in detail. Numerical simulations that involve finite elastic deformations coupled with large nonsteady rotational motions are presented for a beam attached to a rotating base and for the same beam with an end body. Effects such as centrifugal stiffening and softening, membrane strain effect, and vibrations induced by Coriolis forces are accommodated. The effects of rotary inertia as well as shear deformation are included in the equations of motion. These simulations demonstrate the capability of the general dynamical formalism in handling multibody (rigid or flexible) dynamics. An efficient recursive formulation of multibody dynamics is derived, based on the general dynamical equations of motion, which, in turn, are obtained from Lagrange's form of d'Alembert's principle. The efficiency derives from recurrence relations of the (angular) velocity coefficients, (angular) velocities, (angular) accelerations, and generalized forces. Kinematic relations between contiguous bodies that are connected by revolute or prismatic joints are defined by relative joint coordinates. Intermediate reference frames are introduced for convenience in defining various joint displacements between the interconnected deformed bodies. In this thesis, we restrict the discussion to open-loop kinematic chains, composed of bodies connected by joints. A beam rigidly attached at its outer end to a rotating base is studied to illustrate this recursive formulation.Ph.D.Aerospace EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/105816/1/9208691.pdfDescription of 9208691.pdf : Restricted to UM users only