A second case of intrauterine growth retardation and primary hypospadias associated with a trisomy 22 placenta but with biparental inheritance of chromosome 22 in the fetus

We report a case of severe intrauterine growth retardation (IUGR) and hypospadias in association with trisomy 22 diagnosed following chorionic villus sampling (CVS). Subsequent analysis of amniotic fluid cultures showed a normal male karyotype, 46,XY. As a previous case had been reported with similar abnormalities, in association with maternal uniparental disomy (UPD) 22, molecular studies were also performed. Microsatellite marker studies showed biparental inheritance. Follow-up studies after delivery showed a normal cell line in lymphocytes with the trisomy appearing to be confined to the placenta. The present case concurs with other earlier reports that maternal UPD for chromosome 22 has no impact on the phenotype. The features seen in the fetus are most likely the result of placental dysfunction due to trisomy, tissue-specific mosaicism and/or the effects of local growth restriction. Copyright © 2002 John Wiley & Sons, Ltd.     

Psychological aspects of prenatal diagnosis and its implications in multiple pregnancies

Couples expecting twins are often unrealistically optimistic and are therefore unprepared for the complications as well as the practical and emotional impact the birth of twins can have on the family. All such couples will need information and support throughout the pregnancy and beyond. In this review, the various aspects that should be addressed are discussed, in particular, health care workers and counsellors need to be aware of the stress experienced by parents who have been through prolonged treatment for infertility or who face the special problems associated with the loss of one twin (implies the loss could be other than death). Copyright © 2005 John Wiley & Sons, Ltd.     

The toxicology of climate change: Environmental contaminants in a warming world

Climate change induced by anthropogenic warming of the earth's atmosphere is a daunting problem. This review examines one of the consequences of climate change that has only recently attracted attention: namely, the effects of climate change on the environmental distribution and toxicity of chemical pollutants. A review was undertaken of the scientific literature (original research articles, reviews, government and intergovernmental reports) focusing on the interactions of toxicants with the environmental parameters, temperature, precipitation, and salinity, as altered by climate change. Three broad classes of chemical toxicants of global significance were the focus: air pollutants, persistent organic pollutants (POPs), including some organochlorine pesticides, and other classes of pesticides. Generally, increases in temperature will enhance the toxicity of contaminants and increase concentrations of tropospheric ozone regionally, but will also likely increase rates of chemical degradation. While further research is needed, climate change coupled with air pollutant exposures may have potentially serious adverse consequences for human health in urban and polluted regions. Climate change producing alterations in: food webs, lipid dynamics, ice and snow melt, and organic carbon cycling could result in increased POP levels in water, soil, and biota. There is also compelling evidence that increasing temperatures could be deleterious to pollutant-exposed wildlife. For example, elevated water temperatures may alter the biotransformation of contaminants to more bioactive metabolites and impair homeostasis. The complex interactions between climate change and pollutants may be particularly problematic for species living at the edge of their physiological tolerance range where acclimation capacity may be limited. In addition to temperature increases, regional precipitation patterns are projected to be altered with climate change. Regions subject to decreases in precipitation may experience enhanced volatilization of POPs and pesticides to the atmosphere. Reduced precipitation will also increase air pollution in urbanized regions resulting in negative health effects, which may be exacerbated by temperature increases. Regions subject to increased precipitation will have lower levels of air pollution, but will likely experience enhanced surface deposition of airborne POPs and increased run-off of pesticides. Moreover, increases in the intensity and frequency of storm events linked to climate change could lead to more severe episodes of chemical contamination of water bodies and surrounding watersheds. Changes in salinity may affect aquatic organisms as an independent stressor as well as by altering the bioavailability and in some instances increasing the toxicity of chemicals. A paramount issue will be to identify species and populations especially vulnerable to climate–pollutant interactions, in the context of the many other physical, chemical, and biological stressors that will be altered with climate change. Moreover, it will be important to predict tipping points that might trigger or accelerate synergistic interactions between climate change and contaminant exposures.     

The effects of parametric uncertainties in simulations of a reactive plume using a Lagrangian stochastic model

A combined Lagrangian stochastic model with micro-mixing and chemical sub-models is used to investigate a reactive plume of nitrogen oxides (NO_x) released into a turbulent grid flow doped with ozone (O₃). Sensitivities to the model input parameters are explored for different source NO_x scenarios. The wind tunnel experiments of Brown and Bilger (1996) provide the simulation conditions for the first case study where photolysis reactions are not included and the main uncertainties occur in parameters defining the turbulence scales, source size and reaction rate of NO with O₃. Using nominal values of the parameters from previous studies, the model gives a good representation of the radial profile of the conserved mean scalar ${\overline{\Gamma }}_{{\text{NO}}_{\text{x}}}$ although slightly over predicts peak mean NO₂ concentrations ${\overline{\Gamma }}_{{\text{NO}}_{\text{2}}}$ compared to the experiments. The high dimensional model representation (HDMR) method is used to investigate the effects of uncertainties in model inputs on the simulation of chemical species concentrations. For this scenario, the Lagrangian velocity structure function coefficient has the largest impact on simulated ${\overline{\Gamma }}_{{\text{NO}}_{\text{x}}}$ profiles. Photolysis reactions are then included in a chemical scheme consisting of eight reactions between species NO, O, O₃ and NO₂. Independent and interactive effects of 22 input parameters are studied for two source NO_x scenarios using HDMR, including turbulence parameters, temperature dependant rate parameters, photolysis rates, temperature, fraction of NO in total NO_x at the source and background ozone concentration [O₃]. For this reactive case, the variance in the predicted mean plume centre ${\overline{\Gamma }}_{{\text{O}}_{\text{3}}}$ is caused by parameters describing both physical (mixing time-scale coefficient) and chemical processes (activation energy for the reaction O₃+NO). The variance in predicted plume centre ${\overline{\Gamma }}_{{\text{NO}}_{\text{2}}}$ and root mean square NO₂ concentration ${\gamma }_{{\text{NO}}_{\text{2}}}^{\prime }$, is strongly influenced by the fraction of NO in the source NO_x, and to a lesser extent the mixing time-scale coefficient. Adjusting the latter gives improved agreement with the Brown and Bilger experiment. Some weak parameter interactions are observed.     

The impacts of knowledge of the past on preferences for future landscape change

In this paper, we investigate whether people's knowledge of the past influences their preferences and values towards future landscape change. "Knowledge of the past" is one aspect of the information set held by individuals, and a well-established finding in economics is that changes in information can change preferences and values. The particular aspects of knowledge of the past we work with here are: (i) awareness of past landuse, as represented by woodland cover and (ii) awareness of differing and sometimes contradictory literary impressions of this past landscape. The case studies used here relate to prospective changes in woodland cover in two UK national parks, the Lake District and the Trossachs. We find that people who are made aware that the landscape has changed over time, or that perceptions of the landscape have changed over time, are more likely to favour changes to the current landscape (are less likely to favour the status quo). Knowledge of the past therefore seems to have an impact on preferences for future landscapes. We also investigate the impacts on preferences of how "special", how "wild" and how "worked in" people perceive the landscapes of these two national parks to be.     

Adaptive management for mitigating Cryptosporidium risk in source water: A case study in an agricultural catchment in South Australia

Water-borne pathogens such as Cryptosporidium pose a significant human health risk and catchments provide the first critical pollution ‘barrier’ in mitigating risk in drinking water supply. In this paper we apply an adaptive management framework to mitigating Cryptosporidium risk in source water using a case study of the Myponga catchment in South Australia. Firstly, we evaluated the effectiveness of past water quality management programs in relation to the adoption of practices by landholders using a socio-economic survey of land use and management in the catchment. The impact of past management on the mitigation of Cryptosporidium risk in source water was also evaluated based on analysis of water quality monitoring data. Quantitative risk assessment was used in planning the next round of management in the adaptive cycle. Specifically, a pathogen budget model was used to identify the major remaining sources of Cryptosporidium in the catchment and estimate the mitigation impact of 30 alternative catchment management scenarios. Survey results show that earlier programs have resulted in the comprehensive adoption of best management practices by dairy farmers including exclusion of stock from watercourses and effluent management from 2000 to 2007. Whilst median Cryptosporidium concentrations in source water have decreased since 2004 they remain above target levels and put pressure on other barriers to mitigate risk, particularly the treatment plant. Non-dairy calves were identified as the major remaining source of Cryptosporidium in the Myponga catchment. The restriction of watercourse access of non-dairy calves could achieve a further reduction in Cryptosporidium export to the Myponga reservoir of around 90% from current levels. The adaptive management framework applied in this study was useful in guiding learning from past management, and in analysing, planning and refocussing the next round of catchment management strategies to achieve water quality targets.     

Determining sources of dissolved organic carbon and disinfection byproduct precursors to the McKenzie River, Oregon

This study was conducted to determine the main sources of dissolved organic carbon (DOC) and disinfection byproduct (DBP) precursors to the McKenzie River, Oregon (USA). Water samples collected from the mainstem, tributaries, and reservoir outflows were analyzed for DOC concentration and DBP formation potentials (trihalomethanes [THMFPs] and haloacetic acids [HAAFPs]). In addition, optical properties (absorbance and fluorescence) of dissolved organic matter (DOM) were measured to provide insight into DOM composition and assess whether optical properties are useful proxies for DOC and DBP precursor concentrations. Optical properties indicative of composition suggest that DOM in the McKenzie River mainstem was primarily allochthonous--derived from soils and plant material in the upstream watershed. Downstream tributaries had higher DOC concentrations than mainstem sites (1.6 +/- 0.4 vs. 0.7 +/- 0.3 mg L(-1)) but comprised < 5% ofmainstem flows and had minimal effect on overall DBP precursor loads. Water exiting two large upstream reservoirs also had higher DOC concentrations than the mainstem site upstream of the reservoirs, but optical data did not support in situ algal production as a source of the added DOC during the study. Results suggest that the first major rain event in the fall contributes DOM with high DBP precursor content. Although there was interference in the absorbance spectra in downstream tributary samples, fluorescence data were strongly correlated to DOC concentration (R2 = 0.98), THMFP (R2 = 0.98), and HAAFP (R2 = 0.96). These results highlight the value of using optical measurements for identifying the concentration and sources of DBP precursors in watersheds, which will help drinking water utilities improve source water monitoring and management programs.     

Current Status of Mathematical Models for Population Dynamics of Prymnesium parvum in a Texas Reservoir1

Grover, James P., Jason W. Baker, Daniel L. Roelke, and Bryan W. Brooks, 2010. Current Status of Mathematical Models for Population Dynamics of Prymnesium parvum in a Texas Reservoir. Journal of the American Water Resources Association (JAWRA) 46(1):92-107. DOI: 10.1111/j.1752-1688.2009.00393.x Abstract: Blooms of the harmful alga Prymnesium parvum have apparently increased in frequency in inland waters of the United States, especially in western Texas. A suite of mathematical models was developed based on a chemostat (or continuously stirred tank reactor) framework, and calibrated with data from Lake Granbury, Texas. Inputs included data on flows, salinity, irradiance, temperature, zooplankton grazing, and nutrients. Parameterization incorporated recent laboratory studies relating the specific growth rate of P. parvum to such factors. Models differed in the number of algal populations competing with P. parvum, and whether competition occurred only by consumption of shared nutrients, or additionally through production of an allelopathic chemical by one of the populations, parameterized as cyanobacteria. Uncalibrated models did not reproduce the observed seasonal dynamics of P. parvum in Lake Granbury, which displayed a maximum population in late February during a prolonged bloom in cooler weather, and reduced abundance in summer. Sensitivity analyses suggested two modifications leading to predictions that better resembled observations. The first modification greatly reduces the optimal temperature for growth of P. parvum, an approach that disagrees with laboratory experiments indicating a strong potential for growth at temperatures above 20°C. The second modification increases the growth rate of P. parvum at all temperatures, in models including cyanobacterial allelopathy. Despite these adjustments, calibrated models did not faithfully simulate all features of the seasonal dynamics of P. parvum.     

Application of OMI observations to a space-based indicator of NOx and VOC controls on surface ozone formation

We investigated variations in the relative sensitivity of surface ozone formation in summer to precursor species concentrations of volatile organic compounds (VOCs) and nitrogen oxides (NO_x) as inferred from the ratio of the tropospheric columns of formaldehyde to nitrogen dioxide (the “Ratio”) from the Aura Ozone Monitoring Instrument (OMI). Our modeling study suggests that ozone formation decreases with reductions in VOCs at Ratios <1 and NO_x at Ratios >2; both NO_x and VOC reductions may decrease ozone formation for Ratios between 1 and 2. Using this criteria, the OMI data indicate that ozone formation became: 1. more sensitive to NO_x over most of the United States from 2005 to 2007 because of the substantial decrease in NO_x emissions, primarily from stationary sources, and the concomitant decrease in the tropospheric column of NO₂, and 2. more sensitive to NO_x with increasing temperature, in part because emissions of highly reactive, biogenic isoprene increase with temperature, thus increasing the total VOC reactivity. In cities with relatively low isoprene emissions (e.g., Chicago), the data clearly indicate that ozone formation became more sensitive to NO_x from 2005 to 2007. In cities with relatively high isoprene emissions (e.g., Atlanta), we found that the increase in the Ratio due to decreasing NO_x emissions was not obvious as this signal was convolved with variations in the Ratio associated with the temperature dependence of isoprene emissions and, consequently, the formaldehyde concentration.