Molecular structural characteristics of estrogen receptor modulators as determinants of estrogen receptor selectivity.

This review will discuss the structural determinants and requirements necessary for estrogen receptors alpha and beta selectivity and ligand-receptor binding affinity. In addition, strategies likely to result in the development of a pharmacophore model that account for the differences in estrogenic effects between different ligands will be discussed.

Molecular structural characteristics as determinants of estrogen receptor selectivity.

Recent reports that a wide variety of natural and man-made compounds are capable of competing with natural hormones for estrogen receptors serve as timely examples of the need to advance screening techniques to support human health and ascertain ecological risk. Quantitative structure-activity relationships (QSARs) can potentially serve as screening tools to identify and prioritize untested compounds for further empirical evaluations. Computer-based QSAR molecular models have been used to describe ligand-receptor interactions and to predict chemical structures that possess desired pharmacological characteristics. These have recently included combined and differential relative binding affinities of potential estrogenic compounds at estrogen receptors (ER) alpha and beta. In the present study, artificial neural network (ANN) QSAR models were developed that were able to predict differential relative binding affinities of a series of structurally diverse compounds with estrogenic activity. The models were constructed with a dataset of 93 compounds and tested with an additional dataset of 30 independent compounds. High training correlations (r2=0.83-0.91) were observed while validation results for the external compounds were encouraging (r2=0.62-0.86). The models were used to identify structural features of phytoestrogens that are responsible for selective ligand binding to ERalpha and ERbeta. Numerous structural characteristics are required for complexation with receptors. In particular, size, shape and polarity of ligands, heterocyclic rings, lipophilicity, hydrogen bonding, presence of quaternary carbon atom, presence, position, length and configuration of a bulky side chain, were identified as the most significant structural features responsible for selective binding to ERalpha and ERbeta.

Quantifying submarine groundwater discharge in the coastal zone via multiple methods.

Submarine groundwater discharge (SGD) is now recognized as an important pathway between land and sea. As such, this flow may contribute to the biogeochemical and other marine budgets of near-shore waters. These discharges typically display significant spatial and temporal variability making assessments difficult. Groundwater seepage is patchy, diffuse, temporally variable, and may involve multiple aquifers. Thus, the measurement of its magnitude and associated chemical fluxes is a challenging enterprise. A joint project of UNESCO and the International Atomic Energy Agency (IAEA) has examined several methods of SGD assessment and carried out a series of five intercomparison experiments in different hydrogeologic environments (coastal plain, karst, glacial till, fractured crystalline rock, and volcanic terrains). This report reviews the scientific and management significance of SGD, measurement approaches, and the results of the intercomparison experiments. We conclude that while the process is essentially ubiquitous in coastal areas, the assessment of its magnitude at any one location is subject to enough variability that measurements should be made by a variety of techniques and over large enough spatial and temporal scales to capture the majority of these changing conditions. We feel that all the measurement techniques described here are valid although they each have their own advantages and disadvantages. It is recommended that multiple approaches be applied whenever possible. In addition, a continuing effort is required in order to capture long-period tidal fluctuations, storm effects, and seasonal variations.

Off-label use of misoprostol in gynaecology.

Clinical use of drugs is approved for specified clinical indication, route of administration, dose and population group. Off-label prescribing of a registered medicine occurs outside of these parameters and may be justified by pharmacology and physiology, as well as sufficient evidence from published clinical trials and reviews. Misoprostol and mifepristone in combination have recently been registered in Australia for medical termination of pregnancy in women of child-bearing age. There is good clinical evidence for efficacy and safety of misoprostol in uterine evacuation in both miscarriage and termination of pregnancy. The pharmacological effects of misoprostol on the uterus and clinical outcomes in both early miscarriage and abortion are comparable. Medical management of miscarriage with misoprostol in Australia is performed off-label. A woman presenting with first trimester miscarriage must be clearly informed that use of misoprostol in her case is for a non-approved indication. This raises the issue of inequity in her management compared with that of first trimester medical abortion, including being treated off-label and the potential cost of non-subsidised medication. The clinician must also be careful to use an evidence-based protocol that would withstand medicolegal challenge in the case of an adverse outcome.

The mutagenic screening of fourteen imidazo compounds using a modified Ames' test.

Eight imidazo[1,2-alpha] pyrimidine derivatives and six cyclic guanidine derivatives were synthesized in order to study their physiological activity. Mutagenic effects were not detected with any compound in a modified Ames' Salmonella test using TA100, TA98, and TA1537, with or without S9. No inhibition of growth was observed with any test compound. Positive and negative controls behaved as expected.