Fundamental Toxicological Sciences

2025 - Vol. 12

2025 - Vol. 12

Letter
Development of a keratin film-based assay for bacterial removal and adherence, and examination of the influence of fucoidan on skin bacteria Vol.12, No.1, p.21-27
Akihiro Michihara , Chiharu Furukawa , Hiroshi Matsuoka , Satoko Fujioka , Takafumi Sugimoto , Rika Koyano
Released: February 06, 2025
Abstract Full Text PDF[2M]

The outer layer of the epidermis, called the stratum corneum (SC), comprises keratin-rich cells and intercorneal lipids. Staphylococcus aureus has been linked to the fragility of the stratum corneum and formation of atopic dermatitis (AD) lesions. Thus, binding of keratin to bacteria may reflect their binding to the AD-like stratum corneum. In this study, keratin films were prepared using keratin extracted from hair and their potential for bacterial removal and adhesion was investigated using chlorine dioxide, which exhibits bactericidal effects, and fucoidan, which is thought to inhibit bacterial adhesion. The results showed that chlorine dioxide was effective at the removal of S. aureus, whereas fucoidan effectively inhibited bacterial adhesion. Therefore, keratin films can be used to evaluate bacterial removal and inhibition of bacterial adhesion, and the results of this evaluation may reflect those of the AD-like stratum corneum. Using these methods, the effects of fucoidan on indigenous skin bacteria (Staphylococcus epidermidis and Cutibacterium acnes) and general bacteria (Escherichia coli) involved in moisturization were investigated. The results showed that fucoidan inhibited adhesion of S. epidermidis and S. aureus, but did not remove bacteria. Overall, the fucoidan (1700 kDa) used in this study has the potential to prevent and treat AD by inhibiting S. aureus adhesion and improving moisturization by maintaining C. acnes.

Toxicomics Report
Increased expression of TRPM8 and p21/Cip1 in epithelial carcinoma cells in confluent conditions Vol.12, No.1, p.17-20
Tomofumi Fujino
Released: February 06, 2025
Abstract Full Text PDF[1M]

Based on that TRPM8 is a key factor of normal cell-carcinoma cell interaction and there is a tendency for proliferation of some cell types that are repressed in a high-density state rather than in a low-density state, we attempted to clarify the relationship between direct cell-cell interactions and expression of TRPM8, repressor of carcinoma cell proliferation. We examined TRPM8 and p21/Cip1 levels in normal and carcinoma epithelial cells at low and high cell density (confluent). TRPM8 and p21/Cip1 levels in confluent carcinoma cells markedly increased as compared with that of carcinoma cells in low density and normal cells in low density and confluent. When carcinoma cells cultured to confluent were re-seeded at low density, TRPM8 and p21/Cip1 levels decreased, indicating that the direct cell-cell interaction may regulate the expression of TRPM8 and p21/Cip1 in carcinoma cells. Totally, TRPM8 functions as repressor of cell proliferation in the condition which enables direct interaction between carcinoma cells occurs.

Original Article
Effects of excessive fructose on embryo-fetal development in rats Vol.12, No.1, p.7-15
Kota Tanioka , Kaoru Toyoda , Masaru Naito , Tadakazu Takahashi , Toshiyuki Shoda
Released: January 21, 2025
Abstract Full Text PDF[1M]

Fructose, a simple carbohydrate, is contained in fruits and honey. It is widely used as a commercial sweetener for beverages and foods and the average fructose intake in the United States was reported to be 49 g/day from 1999 to 2004. It has been reported that excessive intake of fructose induces developmental disorders of the offspring in rats, particularly abnormal glucose and lipid metabolism and neurodevelopment. However, it has not been reported whether excessive intake of fructose induces congenital morphological abnormalities in fetuses. Therefore, we investigated whether an excessive intake of fructose during pregnancy induces congenital morphological abnormalities in the fetus in rats. Pregnant rats were fed a diet containing 13 g, 26 g, 39 g and 65 g fructose / 66 g carbohydrate in 100 g diet, respectively, for the 13% to 65% Fru diet groups (equivalent to about 500, 1000, 1500 and 2500 g/man/day in humans) or control diet from the day after mating until the end of gestation. Caesarean section was performed on gestation day 20, and the fetuses were examined for caesarean section parameters (fetal viability, fetal body weight, placental weight) and fetal external, skeletal and visceral abnormalities. There were no changes/findings in the caesarean section parameters or fetal morphology in any of the fructose diet groups. In conclusion, excessive intake of fructose during gestation did not induce congenital morphological abnormalities in rat fetuses and did not affect fetal viability or development.

Letter
Identification of lotus cultivar-specific rhizome compounds and evaluation of their growth inhibitory activity against Fusarium commune Vol.12, No.1, p.1-5
Yusuke Hanaki , Yasumasa Hara , Miu Mori , Keita Tomiyoshi
Released: January 15, 2025
Abstract Full Text PDF[2M]

Lotus (Nelumbo nucifera) is an aquatic vegetable cultivated in Asia. Lotus rhizome rot is a sever disease that reduces productivity. We extracted and analyzed the compounds contained in the seed rhizomes of ‘Bicchu’ and ‘Lotus,’ cultivars that differ in resistance to rhizome rot. Interestingly, triglycerides were identified only in ‘Lotus,’ which exhibits a stronger disease resistance than ‘Bicchu.’ However, trilinolein, one of the major triglycerides in rhizomes, did not inhibit the growth of Fusarium commune isolated from rhizomes. Therefore, the differences in the rhizome lipid contents were unrelated to their resistance to rhizome rot. Although in this study we analyzed the major compounds in uninfected rhizomes, certain minor anti-fungal phytochemicals in disease-resistant rhizomes might be induced post-infection with pathogenic fungi. This cultivar comparison approach would be useful for further comprehensive studies on these phytochemicals.