A Theoretical Model for Utilizing Mammalian Pharmacology and Safety Data to Prioritize Potential Impacts of Human Pharmaceuticals to Fish

Due to the potential for long-term, low-level exposure of environmental species to pharmaceuticals in the environment, concerns over chronic ecotoxicity have been raised. Pharmaceuticals typically have specific enzyme and receptor-based modes of action, which are extensively studied in mammals during drug development. A survey of the literature demonstrated that there is conservation of many enzyme/receptor systems between mammalian and teleost systems. Based on this conservation of enzyme/receptor systems across teleost species, a model has been developed to utilize the information from mammalian pharmacology and toxicology studies to evaluate the potential for chronic receptor mediated responses in fish. In this model, a measured human therapeutic plasma concentration (H_TPC) is compared to a predicted steady state plasma concentration (F_SSPC) in fish, and an effect ratio (ER = H_TPC/F_SSPC) is computed. The lower the ER, the greater the potential for a pharmacological response in fish. Data collection and model validation will strengthen the applicability of this approach as a viable tool for prioritizing research initiatives that examine the potential impact of pharmaceuticals on fish.     

Coral calcification rates by the buoyant weight technique: Effects of alizarin staining

The buoyant weight method has been used in a laboratory experiment over an 18-day period to assess effects of alizarin staining on the calcification rate of the hermatypic coral Diploria strigosa (Dana). Exposure of corals to a concentration of 10 mg/l alizarin for 24 h in a flow-through system caused a significant depression in calcification for a period of up to 6 days. It is suggested that such initial calcification depressions after staining could affect absolute growth measurements and cause synergistic effects with experimental manipulation of environmental conditions unless an appropriate recovery period is allowed.     

The isolation of a low molecular weight inhibitor of [H]TdR incorporation into hepatic DNA

An inhibitor of [³H]TdR incorporation into rat liver DNA has been partially purified from bovine and rat livers and from bovine serum. The material isolated does not contain TdR: it is species non-specific, tissue-specific, and non-cytotoxic, and may contain a hepatic chalone.     

Luteinizing hormone response to an oestradiol challenge in 5 intersex pigs possessing ovotestes

After challenge with oestradiol benzoate, the mean maximum LH concentration in 5 XX intersex pigs possessing ovarian and testicular tissue, or only testicular tissue, was 2.10 (+/- 0.41) ng/ml compared with 8.9 ng/ml in mature domestic gilts. These results indicate that exposure of the pig brain to testosterone before Day 30 of gestation is important, or that early testicular secretions other than testosterone are involved in the determination of brain gender. The observation that some intersex pigs show normal oestrous cycles implies that the response to these prenatal factors is primarily quantitative rather than qualitative.