Do racial differences exist in second-trimester maternal hCG levels? a study of 23 369 patients

In Down syndrome screening by maternal serum human chorionic gonadotropin (hCG) determination at 15, 16, 17, and 18 weeks of gestation, we prospectively examined 23 369 sera from white (21 549), North African (970), black African (525), and Asian (325) patients. When expressed as multiples of the median (MOM), no difference was observed between white, North African, and black African patients. However, higher serum hCG concentrations were noted in Asians, for whom we therefore recommend correction of hCG values before calculation of the risk of Down syndrome.     

Phototransformation of methabenthiazuron in the presence of nitrate and nitrite ions

The influence of nitrate and nitrite ions on the degradation of methabenzthiazuron upon irradiation using artificial solar light has been investigated. The rate of degradation of methabenzthiazuron (1 microM) was accelerated by NO3- (0.1 mM) by a factor of 10. The irradiation of methabenzthiazuron (0.1 mM) in the presence of NO3- (1 mM) or NO2- (0.1 mM) yielded numerous intermediary photoproducts. Mineralization was achieved after prolonged exposure. Some were identified with the help of LC-ESI-MS and flow injection APCI-MS techniques. Both oxidations of the aromatic ring and of the urea chain were observed. The former started by hydroxylation of the ring. Further oxidation of the ring led to cleavage of the benzenic ring with formation of dialdehydic, diacidic and anhydric compounds. Complete removal of the lateral urea chain took place subsequently to demethylation of the terminal methyl group and loss of the CO-NH2 group. Nitration was a minor process. This work shows that the photodegradation of methabenzthiazuron in the presence of nitrate or nitrite ions is highly non-specific.     

Portal absorption of 14C after ingestion of spiked milk with 14C-phenanthrene, 14C-benzo[a]pyrene or 14C-TCDD in growing pigs

Polycyclic aromatic hydrocarbons (PAHs) and dioxins are lipophilic organic pollutants occurring widely in the terrestrial environment. In order to study the PAHs and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) transfer in the food chain, pigs have been fed with milk mixed either with 14C-phenanthrene, with 14C-benzo[a]pyrene or with 14C-TCDD. The analysis of portal and arterial blood radioactivity showed that both PAHs and TCDD were absorbed with a maximum concentration at 4-6 h after milk ingestion. Then, the blood radioactivity decreased to reach background levels 24 h after milk ingestion. Furthermore, the portal and arterial blood radioactivities were higher for phenanthrene (even if the injected load was the lowest) than these of benzo[a]pyrene or these of TCDD, in agreement with their lipophilicity and water solubility difference. Main 14C absorption occurred during the 1-3 h time period after ingestion for 14C-phenanthrene and during the 3-6 h time period for 14C-benzo[a]pyrene and for 14C-TCDD. 14C portal absorption rate was high for 14C-phenanthrene (95%), it was close to 33% for 14C-benzo[a]pyrene and very low for 14C-TCDD (9%). These results indicate that the three studied molecules have a quite different behaviour during digestion and absorption. Phenanthrene is greatly absorbed and its absorption occurs via the blood system, whereas benzo[a]pyrene and TCDD are partly and weakly absorbed respectively. However these two molecules are mainly absorbed via the portal vein.     

Establishing principal soil quality parameters influencing earthworms in urban soils using bioassays

Potential contamination at ex-industrial sites means that, prior to change of use, it will be necessary to quantify the extent of risks to potential receptors. To assess ecological hazards, it is often suggested to use biological assessment to augment chemical analyses. Here we investigate the potential of a commonly recommended bioassay, the earthworm reproduction test, to assess the status of urban contaminated soils. Sample points at all study sites had contaminant concentrations above the Dutch soil criteria Target Values. In some cases, the relevant Intervention Values were exceeded. Earthworm survival at most points was high, but reproduction differed significantly in soil from separate patches on the same site. When the interrelationships between soil parameters and reproduction were studied, it was not possible to create a good model of site soil toxicity based on single or even multiple chemical measurements of the soils. We thus conclude that chemical analysis alone is not sufficient to characterize soil quality and confirms the value of biological assays for risk assessment of potentially contaminated soils.     

Water to atmosphere fluxes of 131I in relation with alkyl-iodide compounds from the Seine Estuary (France)

This study presents an original work on measurements of stable and radioactive iodinated species in the Seine estuary (France), with estimates fluxes of volatile gaseous species from water to the atmosphere. Various iodinated compounds were identified in water and air in particular 131I in water, what is unusual. Concentrations and behaviour of iodinated elements in the Seine estuary seem similar to what has been observed in other European estuaries. MeI (Methyl Iodide) and Total Volatile Iodine (TVI) fluxes from water to air vary between 392 and 13949 pmol m(-2) d(-1) and between 1279 and 16484 pmol m(-2) d(-1), respectively. Water to air flux of TVI for the Seine river was estimated in the range 4-46 kg y(-1). Measurements of (131)I in water varying between 0.4 and 11.9 Bq m(-3). Fluxes of (131)I from water to atmosphere are in the range 2.4 x 10(5)-1.3 x 10(7)Bq y(-1), close to an annual discharge of (131)I by a nuclear reactor.     

Probationary and non-probationary drivers' nighttime crashes in Western Australia, 1996-2000

INTRODUCTION: This study was designed to explore the temporal aspects of crashes for probationary and non-probationary drivers. METHODS: Data from the West Australian Road Injury Database from 1996-2000 were used to calculate age-sex-specific crash rates per 100,000 person-days and to plot proportions of fatal and hospital crashes by time for probationary and non-probationary drivers. The population attributable risk was used to estimate the potential number of lives saved by nighttime driving restriction in the probationary period. RESULTS: Probationary drivers were seven times more likely to crash than non-probationary drivers. While the highest number of crashes was in the daytime, probationary drivers had a higher proportion of fatal or hospitalization crashes at night than non-probationary drivers. CONCLUSION: Restrictions on driving at night could form part of graduated driver training. Even if some probationary drivers disobeyed the restriction, a substantial reduction in car occupant fatalities and hospitalizations could result.     

Kin associations and direct vs indirect fitness benefits in colonial cooperatively breeding sociable weavers Philetairus socius

Indirect fitness benefits are believed to be an important force behind the evolution of cooperative breeding. However, helpers may associate with their relatives as a result of delayed dispersal, hence, kin associations might be a consequence of demographic viscosity rather than active choice. In addition, recent studies showed that helpers may have access to reproduction therefore direct benefits might also play an important role. Here, we investigate the possible roles of direct genetic benefits and kin associations on helping behavior in the sociable weaver Philetairus socius, a colonial and cooperatively breeding passerine. We used a microsatellite-based genotyping method to describe the genetic structure within nests and colonies. Within a colony, we found considerable genetic structure between males but not females. Sociable weaver colonies have several nests that are simultaneously active, giving individuals a choice of associating with a range of first-order kin to unrelated individuals. Helpers were significantly more related to the young in the helped nests than in other nests of the colony, suggesting an active choice for associating with kin. The helpers were generally offspring or first-order relatives of one (50%) or both (43%) breeders, although more infrequently, seemingly unrelated individuals also helped (7%). We found no supporting evidence of extrapair parentage and hence no direct genetic gains from helping in our population. This strong reproductive skew is contrary to theoretical models predicting conflicts over reproduction in stepfamilies. We discuss whether female decisions and/or other direct benefits of remaining in kin associations or helping might explain the high skew observed.     

Modeling joint production of wildlife and timber

Production of marketed commodities and protection of natural systems often conflict. A focus on only one goal can result in large losses in other goals and may result in inefficient and unsustainable outcomes. In this paper, we develop a method that combines economic and ecological models in a dynamic and spatial analysis to evaluate land use decisions and find cost-effective alternatives for which it is not possible to do better on one objective without harming another objective. The method is demonstrated using timber production and species conservation on a forested landscape over a 100-year planning horizon. Current land use strategies are simulated and compared with cost-effective alternatives. The approach is compared to a static reserve approach, similar to previous studies, and found to produce substantially more efficient management strategies for the case study landscape.     

Characterisation of potentially genotoxic compounds in sediments collected from United Kingdom estuaries

The mutagenic activity bioassay Mutatox was used to assess the mutagenic activity associated with sediments collected from five UK estuaries. Assays were performed on extracts of sediment pore water and residual particulate material isolated from sediment samples collected from the rivers Tyne, Tees, Mersey, and Thames as well as Southampton Water. No mutagenic activity was associated with the pore water extracts, however, 7 of the 28 organic solvent extracts of sediment particulate material contained potential genotoxins. By using Mutatox in association with bioassay-directed fractionation, attempts were made to identify the mutagenic compounds present in the extracts. The fractionation procedure used normal phase solid phase extraction, C18 reverse phase HPLC and cyano/amino bonded silica normal phase HPLC. GC-MS (EI and NICI) analysis was used to identify polycyclic aromatic hydrocarbons (PAH), alkyl substituted PAH, nitro-polycyclic aromatic compounds (nitro-PACs), polycyclic aromatic ketones, oxygenated-PACs, and other known mutagens contributing to the genotoxicity measured in the samples. Some potentially genotoxic compounds remain unidentified.