Pyrethroid insecticide exposure and semen quality of young Japanese men.

The present study aimed at assessing the relationship between exposure to pyrethroid insecticides and semen quality in 323 university students recruited in a population-based manner in Metropolitan Tokyo. Urinary concentrations of pyrethroid insecticide metabolite, 3-phenoxybenzoic acid (3-PBA), were measured by LC/MS/MS and semen parameters were measured by following internationally harmonized protocols. Median urinary 3-PBA concentration was 0.641 ng/mL (specific gravity-adjusted, n=322). Median values of semen volume, sperm concentration, motility, total number of sperm, and total number of motile sperm were 2.5 mL, 56×10(6)/mL, 61%, 141×10(6), and 82×10(6), respectively. Urinary concentration of 3-PBA was not selected as significant in multiple regression models indicating, in contrast to previous findings, that environmental exposure to pyrethroid insecticides did not affect semen quality. This inconsistency may be related to exposure to different pyrethroid insecticides and/or levels of exposure as well as to survey design (hospital- vs population-based subject recruitment).

Noninvasive cross-sectional visualization of enamel cracks by optical coherence tomography in vitro.

INTRODUCTION: Current methods for the detection of enamel cracks are not very sensitive. Optical coherence tomography (OCT) is a promising diagnostic method for creating cross-sectional imaging of internal biological structures by measuring echoes of backscattered light. In this study, swept-source OCT (SS-OCT), a variant of OCT that sweeps the near-infrared wavelength at a rate of 30 kHz over a span of 110 nm centered at 1,330 nm, was examined as a diagnostic tool for enamel cracks. METHODS: Twenty extracted human teeth were visually evaluated without magnification. SS-OCT was conducted on locations in which the presence of an enamel crack was suspected under visual inspection using a photocuring unit as transillumination. The teeth were then sectioned with a diamond saw and directly viewed under a confocal laser scanning microscope (CLSM). RESULTS: Using SS-OCT, the presence and extent of enamel cracks were clearly visualized on images based on backscattering signals. The extension of enamel cracks beyond the dentinoenamel junction could also be confirmed. The diagnostic accuracy of SS-OCT was shown to be superior to that of conventional visual inspection--the area under the receiver operating characteristic curve--for the detection of enamel crack and whole-thickness enamel crack; visual inspection: 0.69 and 0.56, SS-OCT: 0.85 and 0.77, respectively). CONCLUSIONS: Enamel cracks can be clearly detected because of increased backscattering of light matching the location of the crack, and the results correlated well with those from the CLSM.

Endocrine disrupting chemicals in urine of Japanese male partners of subfertile couples: a pilot study on exposure and semen quality.

The concentrations of chemicals with suspected endocrine disrupting effect were measured in urine samples collected from 42 Japanese male partners of couples who had infertility consultation at a gynecology clinic in Tokyo. The urinary analytes included metabolites of 5 phthalate diesters, pyrethroid insecticide (3-phenoxybenzoic acid, 3-PBA) and soy isoflavones (daidzein and equol), and cadmium. The semen parameters (semen volume, concentration and motility) of the male subjects were examined at the clinic as a diagnostic screening. Multiple regression analysis using one of the semen parameters examined as dependent variable and urinary biomarkers with age, body mass index, abstinent period, alcohol drinking, smoking and consumption frequency of selected foods as independent variables. For sperm concentration, urinary mono-n-butyl phthalate was selected as a significant independent variable with positive beta, while urinary daidzein was with negative beta. Consumption frequency of coffee (negative) and fruits (positive) were also significant. For sperm motility, urinary 3-PBA was selected as significant with negative beta as well as detectability of equol and frequency of coffee consumption with negative beta while smoking was with positive beta. This pilot study suggested the pyrethroid exposure level and dietary habit (coffee and soy products) as a significant contributor to poorer semen quality.