Construction of reporter gene assays using CWP and PDR mutant yeasts for enhanced detection of various sex steroids.

BACKGROUND: Sex steroid hormone receptors are classified into three classes of receptors: estrogen receptors (ER) α and ß, androgen receptor (AR), and progesterone receptor (PR). They belong to the nuclear receptor superfamily and activate their downstream genes in a ligand-dependent manner. Since sex steroid hormones are involved in a wide variety of physiological processes and cancer development, synthetic chemical substances that exhibit sex steroid hormone activities have been applied as pharmaceuticals and consumed in large amounts worldwide. They are potentially hazardous contaminants as endocrine disruptors in the environment because they may induce inappropriate gene expression mediated by sex steroid hormone receptors in vivo. RESULTS: To develop simple reporter gene assays with enhanced sensitivity for the detection of sex steroid hormones, we newly established mutant yeast strains lacking the CWP and PDR genes encoding cell wall mannoproteins and plasma membrane drug efflux pumps, respectively, and expressing human ERα, ERß, AR, and PR. Reporter gene assays with mutant yeast strains responded to endogenous and synthetic ligands more strongly than those with wild-type strains. Sex steroid hormone activities in some pharmaceutical oral tablets and human urine were also detectable in these yeast assays. CONCLUSIONS: Yeast reporter gene assay systems for all six steroid hormone receptors, including previously established glucocorticoid receptor (GR) and mineralocorticoid receptor (MR) assay yeasts, are now available. Environmental endocrine disrupters with steroid hormone activity will be qualitatively detectable by simple and easy procedures. The yeast-based reporter gene assay will be valuable as a primary screening tool to detect and evaluate steroid hormone activities in various test samples. Our assay system will strongly support the detection of agonists, antagonists, and inverse agonists of steroid hormone receptors in the field of novel drug discovery and assessments of environmental pollutants.

Development of an ultra-high performance multi-turn TOF-SIMS/SNMS system "MULTUM-SIMS/SNMS".

A new system incorporating a multi-turn time-of-flight secondary ion/sputtered neutral mass spectrometer (TOF-SIMS/SNMS) with laser post-ionization was designed and constructed. This system consists of a gallium focused ion beam, femtosecond (fs) laser for post-ionization, and multi-turn TOF mass spectrometer. When laser post-ionization was used, the secondary ion signal strengths for several metals increased by up to 650 times, and were greater than the values obtained in conventional TOF-SIMS experiments. Use of the multi-turn mass spectrometer resulted in an increase in mass resolving power with increase in the total TOF. The mass resolving power reached to 23,000 after 800 multi-turn cycles, corresponding to a flight path length of 1040 m. These results indicated that this system is very effective for the analysis of valuable materials such as space samples with high sensitivity, high mass resolving power, and high lateral resolution.

[Relationships between participation in community activities and psychosocial and physical health of community-dwelling elderly].

OBJECTIVE: The aim of this study was to clarify relationships between participation in community activities and psychosocial and physical health of community-dwelling elderly. METHODS: The participants of the present study were 413 people selected on the basis of a random 1/3 extraction of people aged 65 or older and living in a rural community in Miyagi prefecture. The baseline survey was conducted in February 2008. One year later, we conducted a follow-up survey to clarify how participation in community activities influenced the elderly. Finally, we analyzed data for 218 people, focusing on influences on psychosocial and physical health using the logistic regression model. The state of community activity was treated as a dependent variable, and mental and physical health indicators were assessed as the independent variables. RESULTS: Of the elderly sample, 63 persons were found to be frequent participants in community activities, 60 were infrequent participants, and 95 did not participate. The frequently participating individuals displayed significantly better results for declines in depression (OR = 0.34, 95% CI: 0.13-0.89), and social participation (OR = 0.12, 95% CI: 0.05-0.29), as well as the TMIG index of competence (OR = 0.26, 95% CI: 0.08-0.78) as compared with those who did not participate. CONCLUSION: These results suggest that community activities prevent deterioration of mental health, improve social health, and maintain higher-level functional capacity among community-dwelling elderly individuals.

Establishment of yeast reporter assay systems to detect ligands of thyroid hormone receptors alpha and beta.

Thyroid hormones are essential for proper development and differentiation in vertebrates. Recently, concern over the disruption of thyroid hormone homeostasis by industrial chemicals and environmental pollutants has been spreading. To evaluate these chemicals, several bioassays have been developed to detect thyroid hormone ligand activity. Nevertheless, a simple and useful assay is required for the assessment of an enormous number of environmental chemicals. We established yeast reporter assays by expression of full-length thyroid hormone receptor (TRalpha or TRbeta) cDNA and of the TR-dependent reporter gene in yeasts. By additional introduction of the general coactivator SRC-1 cDNA into the yeasts, a higher response to endogenous thyroid hormones, thyroxine (T4), and triiodothyronine (T3) was obtained. The EC50 values for T3 were 35 and 1.5nM for TRalpha and TRbeta assay yeasts, respectively. We tested four chemicals, tetrabromobisphenol A, tetramethylbisphenol A, 2-isopropylphenol, and o-t-butylphenol, which are suspected to have thyroid hormone-disrupting activity. All four chemicals showed agonistic activities in both assay yeasts; however, their activities were weak in comparison with endogenous TR ligands. Antagonist activities of 2-isopropylphenol and o-t-butylphenol were also found in the TRalpha yeast assay. Taken together, these assay yeasts will be powerful tools for assessing TR ligand activity of industrial chemicals and environmental pollutants.