Men at risk: occupation and male infertility☆

TP53 alterations in acute myeloid leukemia with complex karyotype correlate with specific copy number alterations, monosomal karyotype, and dismal outcome.

WHO Guidelines for Indoor Air Quality: Selected pollutants.

Antidiabetic activity of Terminalia catappa Linn fruits.

Magnesium (Mg) based alloys have been extensively considered for their use as biodegradable implant materials. However, controlling their corrosion rate in the physiological environment of the human body is still a significant challenge. One of the most effective approaches to address this challenge is to carefully select alloying compositions with enhanced corrosion resistance and mechanical properties when designing the Mg alloys. This paper comprehensively reviews research progress on the development of Mg alloys as biodegradable implant materials, highlighting the effects of alloying elements including aluminum (Al), calcium (Ca), lithium (Li), manganese (Mn), zinc (Zn), zirconium (Zr), strontium (Sr) and rare earth elements (REEs) on the corrosion resistance and biocompatibility of Mg alloys, from the viewpoint of the design and utilization of Mg biomaterials. The REEs covered in this review include cerium (Ce), erbium (Er), lanthanum (La), gadolinium (Gd), neodymium (Nd) and yttrium (Y). The effects of alloying elements on the microstructure, corrosion behavior and biocompatibility of Mg alloys have been critically summarized based on specific aspects of the physiological environment, namely the electrochemical effect and the biological behavior.

Effects of alloying elements on the corrosion behavior and biocompatibility of biodegradable magnesium alloys: a review

Male F-344 rats were exposed by inhalation to gaseous formaldehyde at 0.3, 2, and 15 ppm 6 h/day, 5 days/week for 28 months. Nasal tumors were macroscopically evident in the 15 ppm group from the 14th month and 8 of 32 rats bore such tumors at the 24th month. Histopathological examination revealed both squamous cell papillomas and carcinomas. No nasal tumors were observed in the lower exposure groups (0.3 and 2ppm groups). In the high exposure group (15 ppm group), frequent face washing, coughing and/or crouching position, lacrimation, nasal discharge, and yellow discoloration of the haircoat were observed. Significant decrease in food consumption and body weight was noted, and 20 (88.3%) rats died by the 24th month. Reduced triglyceride levels and liver weights, presumed to be related to the drop in food intake, were also seem in the 15 ppm group. Epithelial cell hyperplasia, hyperkeratosis, and the squamous metaplasia were apparent in all exposure groups. Inflammatory cell infiltration, erosion or edema were evident in all groups, including the 0 ppm and room (RC group) controls. In this; study, a no effect level of formaldehyde vapor could not be obtained because toxicological signs were obvious even with the low exposure group. The benchmark doses for squamous metaplasia and epithelial hyperplasia were 0.25 and 0.24 ppm, respectively.

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Results of a 28-month chronic inhalation toxicity study of formaldehyde in male Fisher-344 rats

Male and female Sprague-Dawley rats were exposed to toluene vapor at 600 and 2000 ppm for 6 h/day, and effects on their fertility were investigated. Females were exposed from 14 days before mating until day 7 of gestation. Males were exposed for a total of 90 days, including the mating period; treatment was begun 60 days before pairing, and toxicity with respect to testicular and reproductive functions was examined. In females of the 2000 ppm-treated group, salivation and lacrimation that may have been caused by CNS depression were observed starting 20 days after exposure. Although no abnormalities were seen in mating behavior or fertility, fetal mortality and the number of dams with dead fetuses increased in the 2000 ppm group. In the males exposed to 2000 ppm toluene for 90 days, an increase in kidney weights and a decrease in thymus weights were observed. Basophilic changes and necrosis of kidney tubules were greater at the higher exposure level. Additionally, decreases in the weights of the epididymides and spermatic count were observed, indicating toxicity of toluene to the male reproductive system in vivo for the first time. In conclusion, embryo-fetal toxic effects were apparent in female rats exposed to toluene before and during the early stage of pregnancy. Subacute exposure to a high level (2000 ppm) of toluene vapor elicited mild toxic changes in the kidneys, thymus, and reproductive organs of males. Toxic effects on fertility and reproduction were thus demonstrated not only in females but also in males exposed to toluene vapor in the present study.

Reproductive and developmental toxicity studies of toluene. II. Effects of inhalation exposure on fertility in rats.

Toluene inhalation induced epididymal sperm dysfunction in rats

Benzene-induced hematopoietic neoplasms including myeloid leukemia in Trp53-deficient C57BL/6 and C3H/He mice.

A multi-wall carbon nanotube (MWCNT) product Mitsui MWNT-7 is a mixture of dispersed single fibers and their agglomerates/aggregates. In rodents, installation of such mixture induces inflammatory lesions triggered predominantly by the aggregates/agglomerates at the level of terminal bronchiole of the lungs. In human, however, pulmonary toxicity induced by dispersed single fibers that reached the lung alveoli is most important to assess. Therefore, a method to generate aerosol predominantly consisting of dispersed single fibers without changing their length and width is needed for inhalation studies. Here, we report a method (designated as Taquann method) to effectively remove the aggregate/agglomerates and enrich the well-dispersed singler fibers in dry state without dispersant and without changing the length and width distribution of the single fibers. This method is base on two major concept; liquid-phase fine filtration and critical point drying to avoid re-aggregation by surface tension. MWNT-7 was suspended in Tert-butyl alcohol, freeze-and-thawed, filtered by a vibrating 25 µm mesh Metallic Sieve, snap-frozen by liquid nitrogen, and vacuum-sublimated (an alternative method to carbon dioxide critical point drying). A newly designed direct injection system generated well-dispersed aerosol in an inhalation chamber. The lung of mice exposed to the aerosol contained single fibers with a length distribution similar to the original and the Taquann-treated sample. Taquann method utilizes inexpensive materials and equipments mostly found in common biological laboratories, and prepares dry powder ready to make well-dispersed aerosol. This method and the chamber with direct injection system would facilitate the inhalation toxicity studies more relevant to human exposure.

Yukio Ogawa

Papers

Results of a 28-month chronic inhalation toxicity study of formaldehyde in male Fisher-344 rats

Reproductive and developmental toxicity studies of toluene. II. Effects of inhalation exposure on fertility in rats.

Toluene inhalation induced epididymal sperm dysfunction in rats

Benzene-induced hematopoietic neoplasms including myeloid leukemia in Trp53-deficient C57BL/6 and C3H/He mice.

An improved dispersion method of multi-wall carbon nanotube for inhalation toxicity studies of experimental animals