Detection of hormones in surface and drinking water in Brazil by LC-ESI-MS/MS and ecotoxicological assessment with Daphnia magna.

The growing use of pharmaceutical drug is mainly due to several diseases in human and in animal husbandry. As these drugs are discharged into waterways via wastewater, they cause a major impact on the environment. Many of these drugs are hormones; in which even at low concentrations can alter metabolic and physiological functions in many organisms. Hormones were found in surface water, groundwater, soil, and sediment at concentrations from nanograms to milligrams per liter of volume--quantities known to cause changes in the endocrine system of aquatic organisms. This study aimed to develop a methodology for hormone detection (estriol, estrone, 17ß-estradiol, 17α-ethinylestradiol, progesterone, and testosterone) on surface and treated water samples. Sample toxicity was assessed by ecotoxicology tests using Daphnia magna. A liquid chromatograph coupled to a mass spectrometer with an electrospray ionization source (LC-ESI-MS/MS) was used for the analysis. The results showed that samples were contaminated by the hormones estriol, estrone, progesterone, 17ß-estradiol, and 17α-ethinylestradiol during the sampling period, and the highest concentrations measured were 90, 28, 26, 137, and 194 ng · L(-1), respectively. This indicates the inflow of sewage containing these hormones at some points in the Piracicaba River in the State of Sao Paulo-Brazil. Results indicated little toxicity of the hormone estriol in D. magna, indicating that chronic studies with this microcrustacean are necessary.

The neurosteroid allopregnanolone impairs object memory and contextual fear memory in male C57BL/6J mice.

Allopregnanolone (ALLO, or 3α-hydroxy-5α-pregnan-20-one) is a steroid metabolite of progesterone and a potent endogenous positive allosteric modulator of GABA-A receptors. Systemic ALLO has been reported to impair spatial, but not nonspatial learning in the Morris water maze (MWM) and contextual memory in rodents. These cognitive effects suggest an influence of ALLO on hippocampal-dependent memory, although the specific nature of the neurosteroid's effects on learning, memory or performance is unclear. The present studies aimed to determine: (i) the memory process(es) affected by systemic ALLO using a nonspatial object memory task; and (ii) whether ALLO affects object memory via an influence within the dorsal hippocampus. Male C57BL/6J mice received systemic ALLO either before or immediately after the sample session of a novel object recognition (NOR) task. Results demonstrated that systemic ALLO impaired the encoding and consolidation of object memory. A subsequent study revealed that bilateral microinfusion of ALLO into the CA1 region of dorsal hippocampus immediately following the NOR sample session also impaired object memory consolidation. In light of debate over the hippocampal-dependence of object recognition memory, we also tested systemic ALLO-treated mice on a contextual and cued fear-conditioning task. Systemic ALLO impaired the encoding of contextual memory when administered prior to the context pre-exposure session. Together, these results indicate that ALLO exhibits primary effects on memory encoding and consolidation, and extend previous findings by demonstrating a sensitivity of nonspatial memory to ALLO, likely by disrupting dorsal hippocampal function.

Fish endocrine disruption responses to a major wastewater treatment facility upgrade.

The urban-water cycle modifies natural stream hydrology, and domestic and commercial activities increase the burden of endocrine-disrupting chemicals, such as steroidal hormones and 4-nonylphenol, that can disrupt endocrine system function in aquatic organisms. This paper presents a series of integrated chemical and biological investigations into the occurrence, fate, and effects of endocrine-disrupting chemicals in the City of Boulder Colorado's WWTF and Boulder Creek, the receiving stream. Results are presented showing the effects of a full-scale upgrade of the WWTF (that treats 0.6 m(3) s(-1) of sewage) from a trickling filter/solids contact process to an activated sludge process on the removal of endocrine-disrupting compounds and other contaminants (including nutrients, boron, bismuth, gadolinium, and ethylenediaminetetraacetic acid) through each major treatment unit. Corresponding impacts of pre- and postupgrade effluent chemistry on fish reproductive end points were evaluated using on-site, continuous-flow experiments, in which male fathead minnows (Pimephales promelas) were exposed for 28 days to upstream Boulder Creek water and WWTF effluent under controlled conditions. The upgrade of the WWTF resulted in improved removal efficiency for many endocrine-disrupting chemicals, particularly 17ß-estradiol and estrone, and fish exposed to the postupgrade effluent indicated reduction in endocrine disruption relative to preupgrade conditions.

Herbicides glyphosate and glufosinate ammonium negatively affect human sperm mitochondria respiration efficiency.

The widespread cultivation of genetically modified organisms (GMOs) led to a widespread use of selective herbicides to which GMOs are resistant, thus increasing the concern about human exposure to them. Glyphosate (GLY) and glufosinate ammonium (GA), the active principles of the main formulations, have been investigated for their effects on human health, mainly cancer and reproductive toxicity. However, little is known about their effects on the molecular mechanisms related to sperm quality. To investigate the effects of GLY and GA on mitochondrial respiration efficiency, we took advantage of our already established ex vivo human sperm mitochondria assay. Since spermatozoa are highly regulated by sex steroids, we tested at first testosterone (T), di-hydroxytestosterone (DHT), 17ß-estradiol (E2) and progesterone (P4). Then, we tested the effects of GLY and GA and of the hormone-like flavonoid quercetin (QRC) in a dose-dependent manner. The 0.1-1000 nM concentration range has been considered because it covers both the sexual hormones physiologically relevant concentrations (10 nM), triggering endogenously hormone-dependent signaling pathways, and the estimated (nM range) QRC dietary intake. Subsequently, co-incubation experiments were carried out with the two herbicides in the presence of 10 nM of each sex steroid and QRC. We found that: i) DHT and QRC are able to significantly reduce mitochondrial functionality at concentrations ≥ 10 nM; ii) GLY and GA negatively affect mitochondrial respiration efficiency; iii) in the presence of 10 nM DHT, the negative effect of GLY was increased; iiii) DHT, QRC and GA target mitochondria by using a mechanism different from GLY.

Images, femininity and cancer: an analysis of an international patient education programme.

This article is an analysis of a cancer patient education programme run by cosmetic companies. I focus on an analysis of imagery, arguing that there are particular discursive elements that the cosmetic companies use in order to make productive the relationship between femininity and cancer. I contextualize this education programme by presenting the controversies regarding cosmetics as they relate to the growth of breast tumours. In doing so, I conclude that conversations and questions about a link between chemicals and cancer are subverted by both ;horror' narratives of cancer and the provocative use of standards of beauty. Such discursive dominance in patient education programmes makes it difficult to engage in a more public understanding of cancer growth as affected by cosmetic chemicals.

In vitro assessment of sex steroids and related compounds in water and sediments - a critical review.

Detection of endocrine disrupting compounds in water and sediment samples has gained much importance since the evidence of their effects was reported in aquatic ecosystems in the 1990s. The aim of this review is to highlight the advances made in the field of in vitro analysis for the detection of hormonally active compounds with estrogenic, androgenic and progestogenic effects in water and sediment samples. In vitro assays have been developed from yeast, mammalian and in a few cases from fish cells. These assays are based either on the hormone-mediated proliferation of sensitive cell lines or on the hormone-mediated expression of reporter genes. In vitro assays in combination with various sample enrichment methods have been used with limits of detection as low as 0.0027 ng L-1 in water, and 0.0026 ng g-1 in sediments for estrogenicity, 0.1 ng L-1 in water, and 0.5 ng g-1 in sediments for androgenicity, and 5 ng L-1 in water for progestogenicity expressed as equivalent concentrations of standard reference compounds of 17ß-estradiol, dihydrotestosterone and progesterone, respectively. The experimental results and limits of quantification, however, are influenced by the methods of sample collection, preparation, and individual laboratory practices.

Influence of persistent contaminants and steroid hormones on glioblastoma cell growth.

Glioblastoma multiforme (GBM), a malignancy characterized by its rapid progression, presents a lower risk of occurrence in women during their reproductive years. Necrosis of brain tissue during tumor invasion releases free lipids, and therefore might release contaminants stored in phospholipid-rich neuronal tissue. This study assesses the growth response of two human glioblastoma cell lines, T98G and U138-MG, treated with environmental chemicals known or likely to persist within the brain. Persistent chlorinated pesticides, industrial contaminants, persistent perfluorinated chemicals, and steroid hormones were assayed over a range of concentrations. Although cytotoxic effects were seen in both T98G and U138-MG cells, proliferative responses occurred only in the T98G cell line. Dichlorodiphenyltrichloroethane (DDT), dichlorodiphenyldichloroethylene (DDE), and polychlorinated biphenyl (PCB) 153 were cytotoxic in both lines at 5000 nM. Perfluorodecanoic acid (PFDA), perfluorooctane sulfonate (PFOS), and testosterone stimulated proliferation in the T98G cells at 500, 1000, and 1000 nM, respectively. However, a perfluorinated salt (ammonium perfluorooctanoate; C8) and a weak androgen (dihydroepiandrosterone; DHEA) did not affect relative cell number in this GBM line, suggesting the proliferative effect is not through the activation of an androgen receptor. Exposure to environmental chemicals that result in a mitogenic response may increase the rate of glioblastoma tumor growth and result in the development of more aggressive forms of GBM tumors.

Biochemical alterations in sex hormone-induced hyperplasia and dysplasia of the dorsolateral prostates of Noble rats.

Simultaneous implantation of intact Noble (Nb) rats with testosterone and 17 beta-estradiol (E2)-filled silastic capsules for 16 weeks caused atypical hyperplasia (dysplasia) and striking enlargement exclusively in the dorsolateral prostates (DLPs) of all animals. The dysplastic lesion may be preneoplastic since long-term administration of these steroids to Nb rats is known to induce a high incidence of adenocarcinoma in the DLP. Treatment of rats with nonaromatizable 5 alpha-dihydrotestosterone (DHT) for 16 weeks caused enlargement but not dysplasia, implicating estrogen as a key factor in the genesis of the proliferative lesion. Compared with controls, the testosterone plus E2 treatment caused a 2.5-fold increase in nuclear type II estrogen binding sites which were confined to the DLP. Neither treatment significantly altered androgen content or levels of androgen receptor in the ventral prostate or DLP. Organ cultures of enlarged DLP containing foci of dysplasia metabolized more [3H]DHT than control tissue, which resulted in increased formation of the 5 alpha-androstane-3 beta, 17 beta-diol (3 beta-androstanediol) metabolite by these explants. Because 3 beta-androstanediol has previously been shown to displace [3H]E2 from cytosolic type I estrogen binding sites, the dysplasia may be caused by hyperstimulation of the DLP by the hormones and their normal metabolites produced in abnormal amounts.

Sex hormone-induced carcinogenesis in Rb-deficient prostate tissue.

The retinoblastoma (Rb) gene product is a prototypic tumor suppressor. Mice lacking the Rb gene are not viable and die in utero at approximately 13 days of gestation. In this study, we have rescued Rb-/- prostates by grafting pelvic organ rudiments from Rb-/- mouse embryos under the renal capsule of adult male nude mouse hosts. Grafts of embryonic pelvic organs developed into functional prostatic tissue. Some of the prostatic tissue generated was further used to construct chimeric prostatic tissue recombinants by combining wild-type rat urogenital mesenchyme (rUGM) with Rb-/- and Rb+/+ prostatic epithelium (PRE). The tissue recombinants were grown as subcapsular renal grafts and treated from the time of grafting with Silastic capsules containing 25 mg of testosterone plus 2.5 mg of estradiol. During 5-8 weeks of hormone treatment, rUGM+Rb+/+PRE tissue recombinants developed prostatic hyperplasia, whereas PRE in rUGM+Rb-/-PRE tissue recombinants developed hyperplasia, atypical hyperplasia, and carcinoma. During carcinogenesis in rUGM+Rb-/-PRE tissue recombinants, prostatic epithelial cells of the basal lineage disappeared, whereas the luminal cells underwent carcinogenesis. Epithelial E-cadherin almost totally disappeared. In all cases, epithelial PCNA labeling was elevated in tissue recombinants containing Rb-/- versus Rb+/+ epithelium. These epithelial changes were associated with almost total loss of smooth muscle cells in the stroma. In contrast, in untreated hosts rUGM+Rb+/+PRE tissue recombinants developed normally, and rUGM+Rb-/-PRE tissue recombinants developed mild epithelial hyperplasia. The results of this study demonstrate that Rb-/- prostatic tissue can be rescued from embryonic lethal mice and used to test its susceptibility to hormonal carcinogenesis. Deletion of the Rb gene predisposes prostatic epithelium to hyperplasia and increases proliferative activity Susceptibility to hormonal carcinogenesis in response to exogenous testosterone + estradiol is manifested in the progression from atypica hyperplasia to carcinoma. Thus, these findings demonstrate that the absence of the Rb tumor suppressor gene may predispose prostatic epithelial cells to carcinogenesis. Rescue of organs from Rb-/- embryos not only provides an opportunity to analyze the Rb gene pathway in the development and progression of prostate cancer but also provides an opportunity for specifically evaluating the role of the Rb pathway in development and carcinogenesis in other organs, such as the mammary gland and colon. Because rUGM greatly stimulates prostatic epithelial proliferation, the tissue recombinant model is a particularly useful tool for assessing the functional role of other genes in prostatic carcinogenesis through use of the appropriate transgenic or gene knockout mice.

Environmental hormones and their impacts on sex differentiation in fathead minnows.

Runoff from lands fertilized with animal manure from concentrated animal feeding operations (CAFOs) is a source of hormones to surface water. In this study we tested the hypothesis that larval fathead minnows exposed to sex steroids singly or in a "typical" CAFO mixture during sex differentiation would respond with changes in the expression of a set of target genes, leading to gonadal abnormalities later in life. In the first experiment, a static daily-renewal system was used to expose larvae during the period of 10-20 days post-hatch (dph) to either 5 ng/L 17ß-trenbolone (17ß-TRB) or 5 ng/L 17α-ethinylestradiol (EE2). In a second experiment, fish were exposed from 0 to 45 dph in a flow-through system to a CAFO mixture composed of steroids and degradates (2-16 ng/L), atrazine and degradates (15-250 ng/L), and nitrate (3-11 mg/L). In the single hormone experiment, expression of genes involved in steroidogenesis (cyp19a, cyp17, and star) was decreased in females. In contrast, no differences in gene expression were observed in fish exposed to the CAFO mixture. However, the majority (84%) of treated males had testes containing an ovarian cavity, indicative of feminization, compared to 0% in the control males. Overall, our results show that: (1) changes in gene expression after single hormone exposures are sex-specific, with females more responsive than males; and (2) phenotypic alterations in testicular development can be elicited by a simulated "CAFO" mixture when fathead minnows are exposed during the first 45 days of development. More research is needed to further discern the complex response of fish to steroid mixtures, especially those associated with runoff from land-applied CAFO waste.

Interactions between hormones and epilepsy.

There is a complex, bidirectional interdependence between sex steroid hormones and epilepsy; hormones affect seizures, while seizures affect hormones thereby disturbing reproductive endocrine function. Both female and male sex steroid hormones influence brain excitability. For the female sex steroid hormones, progesterone and its metabolites are anticonvulsant, while estrogens are mainly proconvulsant. The monthly fluctuations in hormone levels of estrogen and progesterone are the basis for catamenial epilepsy described elsewhere in this issue. Androgens are mainly anticonvulsant, but the effects are more varied, probably because of its metabolism to, among others, estradiol. The mechanisms for the effects of sex steroid hormones on brain excitability are related to both classical, intracellularly mediated effects, and non-classical membrane effects due to binding to membrane receptors. The latter are considered the most important in relation to epilepsy. The different sex steroids can also be further metabolized within the brain to different neurosteroids, which are even more potent with regard to their effect on excitability. Estrogens potentiate glutamate responses, primarily by potentiating NMDA receptor activity, but also by affecting GABA-ergic mechanisms and altering brain morphology by increasing dendritic spine density. Progesterone and its main metabolite 5α-pregnan-3α-ol-20-one (3α-5α-THP) act mainly to enhance postsynaptic GABA-ergic activity, while androgens enhance GABA-activated currents. Seizures and epileptic discharges also affect sex steroid hormones. There are close anatomical connections between the temporolimbic system and the hypothalamus controlling the endocrine system. Several studies have shown that epileptic activity, especially mediated through the amygdala, alters reproductive function, including reduced ovarian cyclicity in females and altered sex steroid hormone levels in both genders. Furthermore, there is an asymmetric activation of the hypothalamus with unilateral amygdala seizures. This may, again, be the basis for the occurrence of different reproductive endocrine disorders described for patients with left-sided or right-sided temporal lobe epilepsy.

Cytostatic and cytotoxic activity of sex steroids against human leukemia cell lines.

We investigated effects of sex steroids and analogs (estradiol, DES, norgestrel, progesterone, medroxyprogesterone, and testosterone) on the proliferation and survival of 10 human leukemia/lymphoma cell lines (HL-60, K562, U937, CEM, KG-1, Jurkat, U266, H929, PA and SUNHL). Micromolar concentrations of sex steroids exerted cytostatic and cytotoxic effects on all cell lines tested, irrespective of their sensitivity to glucocorticoids. The order of potency of sex hormones was: DES > progesterone > or = medroxyprogesterone > testosterone > estradiol >> norgestrel. For progesterone and estradiol, cytostatic effects can be achieved at lower concentrations than cytotoxic effects. The most potent agent, DES, exerted half maximal cytotoxic activity at a median concentration of 4 microM (for 10 leukemia cell lines). Our results provide a basis for the potential therapeutic use of estrogens and progestins in glucocorticoid-resistant leukemias and lymphomas.

Effects of sex steroids on the Syrian hamster liver.

The primary objective of this research project was to study the role of sex steroids in the pathogenesis of cholelithiasis using the Syrian hamster as a model. In addition to the morphological examination of the gallbladder epithelium, we thought it imperative to observe the changes induced in the biliary tract in response to the sex steroid treatment. This report focuses on the morphological changes induced in the liver. The hamsters were randomly divided into 4 groups, control (C), estrogen-treated (E), estrogen and medroxyprogesterone-treated (E+MP), and medroxyprogesterone-treated (MP) groups. The E group hepatocytes demonstrated proliferation of the smooth endoplasmic reticulum, lipofuscin-like granules, aggregates of glycogen rosettes, and dense bodies. Lipid droplets in the hepatocyte cytoplasm as well as the nuclei were detected in this group. E+MP combined treatment induced an exacerbation of all the changes observed in the E group, furthermore, there appeared to be a disruption of the hepatic parenchymal architecture. The MP-treated group also exhibited the architectural changes observed in the E+MP group, but also showed sinusoidal dilation. In response to MP alone, the fatty changes in the liver appeared to be accentuated. A striking feature induced in response to MP treatment, was a focal area suggestive of adenomatous changes.

Effects of prenatal testosterone propionate on the sexual development of male and female rats: a dose-response study.

Testosterone plays a major role in male sexual development. Exposure of females to testosterone in utero can induce masculine characteristics such as anovulation, increased anogenital distance (AGD), absence of nipples, retention of male-like tissues, and agenesis of the lower vagina. In addition, high levels of androgens during fetal development can lead to toxic effects such as reduced litter size and viability. The study of the effects of testosterone administration during sexual differentiation provides a foundation for understanding the effects of environmental androgens on fetuses, a sensitive subpopulation. In the current study, we investigated the ability of a range of concentrations of testosterone propionate (TP) administered prenatally to masculinize female and alter male offspring, and measured maternal and fetal T levels. Pregnant Sprague-Dawley rats were dosed by sc injection on gestational day (GD) 14-19 (GD 1= day of plug) with either corn oil (vehicle; 0.1 ml/rat) or with 0.1 ml of TP solution at 0.1, 0.5, 1, 2, 5, or 10 mg/0.1 ml. Parturition was delayed at 2, 5, and 10 mg TP, litter size was reduced at 5 and 10 mg TP, and pup weight was significantly reduced in both sexes at 0.5 mg TP and higher doses. Viability of offspring was unaffected at any dosage level. Androgenic effects seen at 0.5 mg TP in females included increased AGD at weaning and adulthood, reduced number of areolas and nipples, cleft phallus, small vaginal orifice, and presence of prostate tissue. This dose of TP elevated maternal T levels 10x but had no effect on fetal T levels. At 1 mg TP and above, female AGD on postnatal day (PND) 2 (or postcoital day 24 [gestation length = 22(1/2)]) was increased; areolas and nipples were virtually eliminated; levator ani muscle, bulbourethral glands, and seminal vesicles (2 mg TP and above) were present; none of the females developed a vaginal orifice and many females in the 1 and 2 mg TP dose groups developed a greatly distended, fluid-filled uterus after puberty. Maternal T levels at 1 mg TP were elevated 30x, and female fetal T levels showed an 80% increase. Male offspring displayed a reduced AGD and body weight on PND 2 at 0.5 mg TP and higher doses. These effects were not evident by weaning and male offspring displayed no malformations. We conclude that gestational administration of 0.5 and 1 mg TP masculinizes female offspring without greatly affecting pup viability or pregnancy of the dam. This study provides a useful model for in utero testing of environmental androgens for their potential to induce developmental abnormalities.

Studies for a genotoxic potential of some endogenous and exogenous sex steroids. II. Communication: examination for the induction of cytogenetic damage using the chromosomal aberration assay on human lymphocytes in vitro and the mouse bone marrow micronucleus test in vivo.

The cytogenetic potential of 10 sex steroids (cyproterone acetate, drospirenone, gestodene, cyclodiol, cyclotriol, ethinylestradiol, atamestane, lilopristone, onapristone and propylmesterolone) with various medical indications was determined using the chromosomal aberration test in human lymphocytes in vitro and the mouse bone marrow micronucleus test in vivo. Nine of these sex steroids (gestodene was omitted) were investigated in the human lymphocyte assay and found to be negative with respect to the induction of chromosomal aberrations either with or without metabolic activation. In all assays the highest concentration evaluated was either clearly cytotoxic or, in case of noncytotoxicity, resulted in visible precipitates in the culture medium. Evaluation of the data from the mouse bone marrow micronucleus test indicated that the seven steroids (cyproterone acetate, drospirenone, gestodene, ethinylestradiol, atamestane, onapristone and propylmesterolone) investigated failed to induce enhanced frequencies of micronucleated polychromatic erythrocytes in male and female mice. The steroids were tested up to dose levels which induced signs of toxicity in the experimental animals or, in the case of non toxic compounds, the animals were treated up to the maximum recommended dose of 2 g/kg body weight. Evaluation of all data indicates that the investigated estrogens, progestins and other sex steroids had no genotoxic potential detectable with the chromosomal aberration assay on cultured human lymphocytes or the mouse bone marrow micronucleus test.

Studies for a genotoxic potential of some endogenous and exogenous sex steroids. I. Communication: examination for the induction of gene mutations using the Ames Salmonella/microsome test and the HGPRT test in V79 cells.

The mutagenicity results and data of nine progestins (cyproterone acetate, dehydrospirorenone, gestodene, gestonorone caproate, levonorgestrel, norethisterone, norethisterone acetate, norethisterone enanthate, norethynodrel), one hypothetical metabolite (6,7-epoxy-cyproterone acetate), four estrogens (estradiol, ethinylestradiol, cyclodiol, cyclotriol), and four other sex steroids (atamestane, lilopristone, onapristone, propylmesterolone) are reported. All 17 sex steroids were investigated using the Ames salmonella/microsome direct plate incorporation protocol, and seven were additionally tested using the preincubation modification. Seven sex steroids were also studied in the HG-PRT test with V79 cells for the induction of gene mutations in mammalian cells. The metabolite was examined in the Ames salmonella/microsome assay using the standard protocol and the preincubation modification. In all assays the test compounds were investigated up to concentration levels where cytotoxicity and/or visible precipitation occurred or at least the solubility limit of the test compound was reached. For all assays, evaluation of the data indicates that neither any of the sex steroids nor the hypothetical metabolite was able to induce gene mutations whether in the absence or the presence of an extrinsic metabolizing system (S9 mix).

Toxicity classification and evaluation of four pharmaceuticals classes: antibiotics, antineoplastics, cardiovascular, and sex hormones.

Four different classes of environmental concern are quantitatively and qualitatively assessed for environmental hazards; antibiotics (n = 226), antineoplastics (n = 81), cardiovascular (n = 272), and sex hormones (n = 92). These along with an ECOSAR scan of all pharmaceuticals (n = 2848) were then classified according to the OECD aquatic toxicity classification system. The predicted species susceptibility is: daphnid > fish > algae, and the predicted rank order of relative toxicity: sex hormones > cardiovascular = antibiotics > antineoplastics (Table 1). Generally, a relatively large proportion (1/3) of all pharmaceuticals are potentially very toxic to aquatic organisms (Table 2). The qualitative risk assessment ranking relative to probability and potential severity for human and environmental health effects is: antibiotics > sex hormones > cardiovascular > antineoplastics. (Q)SARs and pharmacodynamic information should be used to prioritize and steer experimental risk assessments of pharmaceuticals, and potentially, also be used in new drug discovery optimizing efficacy and in minimising environmental hazards of new products. Nuclear receptors are relatively well conserved in evolution. Currently, antibacterial resistance represents the most significant human health hazard, and potentially the largest non-target organism hazard is sex hormones acting as endocrine modulators in wildlife. Data for the individual compounds are accessible via.

The induction of NB rat prostatic carcinomas.

The NB rat prostate adenocarcinoma model is one in which microscopic carcinoma can be induced via the use of testosterone and estrogen silastic implants. There is an incidence of large, grossly-positive tumors; which approaches 10% to 15%. Seventy-three percent of the animals subjected to this induction method for periods of 9 to 18 months developed at least microscopic carcinoma. The earliest appearance microscopic foci of carcinoma was after three months of implantation, in which one of 30 animals so treated did show carcinoma. However, 88% of the animals treated for 18 months or longer showed microscopic carcinoma.

Formation of free radicals from steroid hormones: possible significance in environmental carcinogenesis.

In order to clarify the mechanism of environmental carcinogenesis, steroid hormones were checked for formation of free radicals and active oxygen species. In alkaline DMSO in vitro, glucocorticoids, progestines, androgens and estrogens exhibited distinct ESR signals with characteristic hyperfine structures. Accumulated data on a great number of steroid derivatives suggest that an unpaired electron is localized at position 20 in the case of glucocorticoids, whereas it is at position 3 in other steroid hormones. Since experimental conditions include oxygenation reactions and more or less reflect enzymatic reactivity, the results obtained suggest further study on the physiological formation of free radicals from steroid hormone is warranted. Although detection of the free radicals of steroid hormones in several enzyme systems was limited to estrogens, evidence suggests that glucocorticoids as well as androgens may also share the physiological formation of free radicals. The production of active oxygen species was confirmed in certain cases.

Bob was right.

During his career Bob Brent has been instrumental in developing the methodology to use in determining whether an exposure in pregnancy has a harmful effect on the fetus. Experience has also shown the importance of using this approach to determine when an exposure is not teratogenic. Unfortunately, the attendant debate, as illustrated in two examples reviewed, exogenous sex hormones and Bendectin, requires persistence and a thick skin. Bob has recorded in several publications how he carried out these systematic analyses. This literature will be a very valuable legacy.