Fundamental Toxicological Sciences
Online ISSN : 2189-115X
ISSN-L : 2189-115X
Volume 6 , Issue 9
Showing 1-5 articles out of 5 articles from the selected issue
Original Article
  • Noriko Usui, Masahito Ohara, Masaya Ito, Atsushi Noda, Yoshihiko Ito, ...
    2019 Volume 6 Issue 9 Pages 333-340
    Published: 2019
    Released: December 11, 2019
    JOURNALS FREE ACCESS

    In this study, we evaluated the toxicity of 16 veterinary drugs approved in Japan (antimicrobial substances, antiparasitic agents, and disinfectants) using a fish acute toxicity test, Daphnia swimming inhibition test, algae growth inhibition test, and earthworm acute toxicity test. Test organisms included Oryzias latipes, Daphnia magna, Pseudokirchneriella subcapitata, and Eisenia fetida. The tests were performed in accordance with the Organisation for Economic Co-operation and Development guidelines for testing chemicals. In the Globally Harmonized System of Classification and Labelling of Chemicals, when the EC/LC50 value of a substance is < 1 mg/mL, then the substance is classified as Category 1, or highly toxic to aquatic organisms. The results of the present study indicate that the toxicity of tylosin phosphate, lincomycin, oxytetracycline chloride, and chlortetracycline to algae; that of ivermectin to crustaceans and fish; and that of didecyldimethylammonium chloride to all organisms examined should be classified as Category 1. In terrestrial organism, weak toxicity was observed with ivermectin, fenbendazole, and didecyldimethylammonium chloride. These data are considered to be valuable data for actually knowing the toxicity of veterinary drugs, in particular, since there is hardly any data following the guidelines using Eisenia fetida. Our results also suggest that the environmental risk of the tested veterinary drugs might be low at present researched environmental levels in river. In addition, our data indicate that the possibility of many veterinary drugs adversely affecting the environment is low if they are properly used.

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Original Article
  • Tsuyoshi Sadakiyo, Hikaru Watanabe, Hitoshi Mitsuzumi, Shimpei Ushio, ...
    2019 Volume 6 Issue 9 Pages 341-357
    Published: 2019
    Released: December 11, 2019
    JOURNALS FREE ACCESS

    Isomaltodextrin-producing enzymes (PP enzyme) include two extracellular enzymes (α-glucosyltransferase and α-amylase) produced by Paenibacillus alginolyticus PP710. These enzymes are essential for producing isomaltodextrin (IMD), a highly branched α-glucan, from starch. In this study, we evaluated the safety of this PP enzyme. No genotoxicity was observed when the PP enzyme was assayed in standardized bacterial reverse mutation and chromosome aberration tests. An acute toxicity study in rats showed no toxic effects of PP enzyme at 2,000 mg/kg. No animals died, and no effects of enzyme administration were observed in a 14-day repeated oral-dose toxicity study in rats at the maximum dose of 1,000 mg/kg/day. The no observed adverse effect level was determined to be 1,000 mg/kg/day in a 90-day subchronic gavage toxicity study in rats. No animals died, and no abnormal findings due to consumption of the PP enzyme were observed in this study. These safety evaluation results demonstrated that the PP enzyme was safe for application as an ingredient in the manufacturing of the food ingredient IMD.

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Original Article
  • Feng Ye, Guorong Dan, Qinya Zeng, Mingliang Chen, Yuanpeng Zhao, Jin C ...
    2019 Volume 6 Issue 9 Pages 359-366
    Published: 2019
    Released: December 19, 2019
    JOURNALS FREE ACCESS

    SM (Sulfur mustard) is an oily, hydrophobic, and lipophilic chemical agent that damages cells with intricate patterns. CEES (2-chloroethyl ethyl sulfide soluble) is a standard SM analog commonly employed in the toxicity mechanism study. To obtain ideal results in vitro, researchers should disperse CEES well in the medium, avoiding the presence of undissolved droplets. However, such a purpose is not easy to reach under the conventional solution preparation, and the information about droplet formation and function is little available. Here, we showed that phospholipid and triglyceride, two essential components of serum lipids, could prevent CEES from dissolving in water after vortex, which kept partial CEES as small droplets. By detecting CEES level, we proved that residual droplets slowed CEES hydrolysis and conversion. Under the microscope, CEES droplets were observed to degrade and diffuse with time to induce the necrosis and mitochondrial membrane potential decline from nearby cells. In conclusion, the damage pattern of CEES droplets is quite different from that of dissolved CEES, and a low level of phospholipid and triglyceride is beneficial for preventing droplets formation in preparing CEES solution.

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Original Article
  • Yuasa Koki, Tadashi Imamura, Yasue Sakaguchi, Satoshi Kotoura
    2019 Volume 6 Issue 9 Pages 367-382
    Published: 2019
    Released: December 19, 2019
    JOURNALS FREE ACCESS

    To evaluate the safety of chicken breast extract containing plasmalogen, the following three tests were conducted: i) chromosome aberration study with mammalian cells; ii) bacterial reverse mutation test; and iii) 90-day repeated oral dose study in rats. The chromosome aberration study showed that there was no statistically significant increase in the structural aberration rate and the polyploidy aberration rate between the group that was treated with chicken breast extract and the negative-control group. Under the present test conditions, chicken breast extract did not induce chromosomal aberrations. Similarly, in the reverse mutation test, there was no increase in the number of revertant colonies in all of the bacterial strains that more than doubled the negative-control value related to the dose, regardless of the presence or absence of metabolic activation. In other words, chicken breast extract did not exhibit a gene mutation–inducing effect under the present test conditions. No effects were observed in the 90-day repeated oral dose study with the administration of chicken breast extract. Under the present test conditions, the no-observed-adverse-effect level for both male and female rats was 1000 mg/kg/day.

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Original Article
  • Yuka Kohda, Hitoshi Matsumura
    2019 Volume 6 Issue 9 Pages 383-390
    Published: 2019
    Released: December 27, 2019
    JOURNALS FREE ACCESS

    Orexin-A has been suggested to control hypertension, feeding behavior, and obesity. We recently established that long-term consumption of thiamine water by obese diabetic rats leads to reduced obesity and metabolic disorders. In addition, we found that drinking thiamine water daily may modulate oxidative stress-related diseases, such as diabetes and its complications. In the present study, we focused on obesity-related hypertension and plasma orexin-A levels in Otsuka Long–Evans Tokushima Fatty (OLETF) rats under oxidative stress conditions and assessed their cerebral ADP-ribosylated protein expression after drinking thiamine water. The thiamine water-drinking group was administered 2 g thiamine/L in drinking water. Plasma orexin-A content was measured by ELISA testing. ADP-ribosylated protein expression was analyzed in the brain of OLETF rats using Western blotting. Primary experimental characteristics, body weight, and caudal blood pressure were similar among the groups. However, at 28 weeks of thiamine water-drinking, significant decreases in body weight and systolic blood pressure were observed in the diabetic-thiamine group compared to those in the diabetic-control group. Moreover, obese diabetic rats exhibited increased plasma orexin-A levels and poly-ADP-ribosylated protein levels in the brain. Notably, the enhanced plasma orexin-A level and cerebral oxidative stress conditions of the obese diabetic rats were attenuated by drinking thiamine water. The relationship between consumption of thiamine in drinking water and obesity-related hypertension and cerebral oxidative stress status via modulation of plasma orexin-A levels requires further investigation. It is noteworthy that the upregulation of orexin signaling may not only cause hypertension, but also maintain obesity in polyphagia-induced OLETF rats.

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