Chronic toxicity of an environmentally relevant mixture of pharmaceuticals to three aquatic organisms (alga, daphnid, and fish).

Principles of concentration addition and independent action have been used as effective tools to predict mixture toxicity based on individual component toxicity. The authors investigated the toxicity of a pharmaceutical mixture composed of the top 10 detected active pharmaceutical ingredients (APIs) in the Tama River (Tokyo, Japan) in a relevant concentration ratio. Both individual and mixture toxicities of the 10 APIs were evaluated by 3 short-term chronic toxicity tests using the alga Pseudokirchneriella subcapitata, the daphnid Ceriodaphnia dubia, and the zebrafish Danio rerio. With the exception of clarithromycin toxicity to alga, the no-observed-effect concentration of individual APIs for each test species was dramatically higher than the highest concentration of APIs found in the environment. The mixture of 10 APIs resulted in toxicity to alga, daphnid, and fish at 6.25 times, 100 times, and 15,000 times higher concentrations, respectively, than the environmental concentrations of individual APIs. Predictions by concentration addition and independent action were nearly identical for alga, as clarithromycin was the predominant toxicant in the mixture. Both predictions described the observed mixture toxicity to alga fairly well, whereas they slightly underestimated the observed mixture toxicity in the daphnid test. In the fish embryo test, the observed toxicity fell between the predicted toxicity by concentration addition and independent action. These results suggested that the toxicity of environmentally relevant pharmaceutical mixtures could be predicted by individual toxicity using either concentration addition or independent action.

Fish multigeneration test with preliminary short-term reproduction assay for estrone using Japanese medaka (Oryzias latipes).

The most potent chemicals potentially causing adverse effects on fish species are estrogens in human waste.Sewage is a source of these estrogens and it is difficult to reduce. In particular, although the bioactivity of estrone is estimated to be about half of that of estradiol, multiple studies report that more than 100 ng l(­1) of estrone can be detected in urban rivers, including discharges from sewage treatment works; approximately two times as high as estradiol. Few studies have been conducted to investigate the long-term effects of estrone on wildlife; therefore, we conducted fish multigeneration test using Japanese medaka (Oryzias latipes). Medaka were exposed to estrone for 27 weeks across three generations in environmentally relevant concentrations, being 5.74, 11.4, 24.0, 47.1 and 91.4 ng l(­1). No effects on reproduction were observed in the first generation; however, a decline in egg production and fertility was observed in the second generation exposed to 91.4 ng l(­1) estrone, which is lower than some known environmental concentrations in urban environments. Furthermore, histopathological abnormalities were observed in the third generation exposed to both 47.1 and 91.4 ng l(­1), suggesting that estrone possibly exerts severe effects on the third or later generations. However, appearances of testis­ova were observed in the second and third generation they were not consistent with actual effects on reproduction, notwithstanding the testis-ovais regarded as the key evidence for endocrine disruption. Accordingly, we consider that qualitative measurement of abnormalities using histopathological observations is required for appropriate evaluation of endocrine disruption.

Verification of responses of Japanese medaka (Oryzias latipes) to anti-androgens, vinclozolin and flutamide, in short-term assays.

Various testing methods for the detection of the endocrine disruptive activities of chemicals have been developed in freshwater fish species. However, a few relatively easier specific methods for detecting anti-androgenic activities are available for fish. The aim of this study was to verify the papillary process in Japanese medaka (Oryzias latipes) as an indicator of the anti-androgenic activity of chemicals. Japanese medaka were exposed to two types of anti-androgenic compounds, vinclozolin and flutamide, using two short-term assays; one was conformed to the existing short-term reproduction assay using adult fish (adult test) and the other was a test based on the same methods but using juvenile fish at the beginning of exposure (juvenile test). Significant decreases in male papillary processes were observed in the juvenile test treated with the highest concentration of both antiandrogens (640 µg l(-1) vinclozolin and 1000 µg l(-1) flutamide); however, no significant effects were observed in the adult test. Consequently, our results indicate that papillary processes in Japanese medaka can be used as the end-point for screening the anti-androgenic activity of chemicals using juvenile fish for a specific period based on the existing short-term reproduction assay.

Relationship between catechol-O-methyltransferase polymorphism and treatment-resistant schizophrenia.

Catechol-O-methyltransferase (COMT) plays a crucial role in the regulation of central dopaminergic systems. We examined the allelic association of a functional polymorphism of the COMT gene with the clinical manifestations and the response to antipsychotics of 100 schizophrenic patients and 201 healthy controls from the general Japanese population. No statistically significant difference was observed in the allele and genotype frequencies between the schizophrenic patients and the healthy controls. The daily neuroleptic dosage that patients received during their maintenance therapy was significantly higher in patients with the L/L genotype than in the other patients (P < 0.05). The present results suggest that the presence of the COMT genotype does not help in evaluating the susceptibility to the development of schizophrenia, but that it may help in the estimation of treatment-resistant features of schizophrenia.

Association between catechol-O-methyltransferase (COMT) polymorphism and severe alcoholic withdrawal symptoms in male Japanese alcoholics.

Catechol-O-methyltransferase (COMT) plays a crucial role in central dopaminergic systems. The allelic association of a functional polymorphism of the COMT gene with the onset, course and clinical characteristics of alcoholism in 91 male Japanese alcoholics and 114 male Japanese controls was examined. There were no statistically significant differences in the frequency of the allele between the alcoholics and the controls. Visual disturbances and auditory disturbances among alcoholic withdrawal symptoms were, however, significantly different among the three groups (p < 0.05). The present results suggest that COMT activity could partially effect the phenotype of alcoholism, especially the appearance of delirium tremens, in these subjects.