Fetal magnetic resonance imaging (MRI) of ischemic brain injury

The aim of the present study was to demonstrate the usefulness of fetal magnetic resonance imaging (MRI) in ischemic brain injury. We report seven cases of fetal brain ischemia prenatally suspected on ultrasound (US) and confirmed by fetal MRI. Sonographic abnormalities included ventricular dilatation (n=3), microcephaly (n=1), twin pregnancy with in utero death of a twin and suspected cerebral lesion in the surviving co-twin (n=3). MRI was performed with a 1.0 T unit using half-Fourier acquisition single-shot turbo spin-echo (HASTE) sequences between 28 and 35 weeks of gestation. US and MRI images were compared with pathologic findings or postnatal imaging. MRI diagnosed hydranencephaly (n=1), porencephaly (n=2), multicystic encephalomalacia (n=2), unilateral capsular ischemia (n=1), corpus callosum and cerebral atrophy (n=1). In comparison with US, visualization of fetal brain anomalies was superior with MRI. The present cases demonstrate that MRI is a valuable complementary means of investigation when a brain pathology is discovered or suspected during prenatal US. Copyright © 2001 John Wiley & Sons, Ltd.     

Joint propagation of variability and imprecision in assessing the risk of groundwater contamination

Estimating risks of groundwater contamination often require schemes for representing and propagating uncertainties relative to model input parameters. The most popular method is the Monte Carlo method whereby cumulative probability distributions are randomly sampled in an iterative fashion. The shortcoming of the approach, however, arises when probability distributions are arbitrarily selected in situations where available information is incomplete or imprecise. In such situations, alternative modes of information representation can be used, for example the nested intervals known as “possibility distributions”. In practical situations of groundwater risk assessment, it is common that certain model parameters may be represented by single probability distributions (representing variability) because there are data to justify these distributions, while others are more faithfully represented by possibility distributions (representing imprecision) due to the partial nature of available information. This paper applies two recent methods, designed for the joint-propagation of variability and imprecision, to a groundwater contamination risk assessment. Results of the joint-propagation methods are compared to those obtained using both interval analysis and the Monte Carlo method with a hypothesis of stochastic independence between model parameters. The two joint-propagation methods provide results in the form of families of cumulative distributions of the probability of exceeding a certain value of groundwater concentration. These families are delimited by an upper cumulative distribution and a lower distribution respectively called Plausibility and Belief after evidence theory. Slight differences between the results of the two joint-propagation methods are explained by the different assumptions regarding parameter dependencies. Results highlight the point that non-conservative results may be obtained if single cumulative probability distributions are arbitrarily selected for model parameters in the face of imprecise information and the Monte Carlo method is used under the assumption of stochastic independence. The proposed joint-propagation methods provide upper and lower bounds for the probability of exceeding a tolerance threshold. As this may seem impractical in a risk-management context, it is proposed to introduce “a-posteriori subjectivity” (as opposed to the “a-priori subjectivity” introduced by the arbitrary selection of single probability distributions) by defining a single indicator of evidence as a weighted average of Plausibility and Belief, with weights to be defined according to the specific context.     

Dioxin contamination in soils of Southern Vietnam

Dioxin is the common name for polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs), and is abbreviated as PCDD/Fs. In the case of Southern Vietnam, is of high concern dioxin contamination in the areas affected by past-use chemical defoliants. Our study related to the zone considered as a "hot spot"--Bien Hoa Airbase and surrounding areas (Bien Hung Lake). Although the war ended over 30 years ago, the adverse effects on this territory still continue. Soil and sediment were selected for our research as they act as a sink for PCDD/Fs. The samples were taken and analyzed in CECOTOX laboratory following certified procedures. The total amounts of PCDD/Fs (2,3,7,8 related congeners) in the samples were converted into WHO-TEQ and compared with standard values proposed by Canadian environmental quality guidelines. The obtained data shows a relatively high risk (up to 20.4 times higher than (probable effect level) PEL value for sediment and 46 times higher than standard value for soil). The research is continuing on the assessment of dioxin transport in food chain. Moreover, considering the obtained data a complete solution should be found urgently to solve the problem of dioxin contamination in the studied areas.     

Combined approaches to determine the impact of wood fire on PCDD/F and PCB contamination of the environment: a case study

Fires might be the source of persistent organic pollutants (POPs) such as dioxins, furans (PCDD/Fs) and/or polychlorobiphenyls (PCBs) in the environment. In the perspective of defining legal responsibilities a thorough characterization of the impact of such an event should be carried out. However, such characterization is not easy as the environment integrates both local and diffuse sources of such molecules. Thus, a combined approach, which includes gathering field surveys, modeling and laboratory experiments, should be conducted. The objective of this work is to illustrate different approaches to give sufficient insight to determine the actual impact of wood fire on the environment. The work was carried out at the vicinity of a burnt down parcel. The fired material was a mixture of wood and PCB-contaminated soils as the site was a former pyralene-disposal site. Modeling, soil and lichen sampling and experimental combustion were carried out to delineate the contamination for each chemical and to define the area within the fire that was responsible for the environmental contamination. Concentrations of PCDD/F and PCBs were very high on the burnt plot. The combined approach determined that the furans were the predominant compounds in the smoke emitted by the fire. Based on this tracer, it was possible to demonstrate that in terms of environmental contamination of PCDD/F, the impact of the fire was restricted to a 2 km radius from the burnt down plot. For PCBs, no specific tracer was identified. In this case, the delineation of the impact could only be empirical, based on the total concentration of the chemicals.     

Essential oil components decrease pulmonary and hepatic cells inflammation induced by air pollution particulate matter

Outdoor air pollution and fine particulate matter (PM) were recently classified as carcinogenic to humans by the International Agency for Research on Cancer. The exposure to airborne particulate matter also contributes to cardiovascular and respiratory diseases, which are major public health concerns. Up to now, no work has evaluated the ability of essential oils as an alternative medicine to relieve the adverse health effects caused by airborne particulate matter. Here, we investigated for the first time the effects of four essential oil components, trans-anethole, estragole, eugenol and isoeugenol, on the reduction in inflammation induced by particulate matter with an aerodynamic diameter below 2.5 μm (PM_2.5), in human bronchial epithelial (BEAS-2B) and human liver carcinoma (HepG2) cell lines. Anethole is a flavor component of anise and fennel, estragole is occurring in basil, eugenol occurs in clove bud oil and isoeugenol occurs in ylang-ylang. Essential oil components were tested either as free or hydroxypropyl-β-cyclodextrin-encapsulated forms. Control experiments showed that particulate matter (PM_2.5) induced inflammation by secretion of pro-inflammatory cytokines IL-6 and IL-8. Our results show that the addition of either free or encapsulated essential oil components to particulate matter exposed cells decreased up to 96 % the cytokine IL-6 level, and by up to 87 % the cytokine IL-8 level. Overall our findings evidence for the first time that natural essential oil components counteract the inflammatory effects of particulate matter and that encapsulation in cyclodextrins preserved their properties.     

Polycyclic aromatic hydrocarbon derivatives in airborne particulate matter: sources,analysis and toxicity

Polycyclic aromatic hydrocarbons (PAHs) are worldwide pollutants produced mainly during incomplete combustion and pyrolysis of organic substances. PAH derivatives are components with hydrogen on the aromatic ring substituted by carbonyl-, nitro- and hydroxyl-functional groups (N-PAH, O-PAH or OH-PAH), or a group of heterocyclic PAHs containing one sulfur atom in place of a carbon atom in the aromatic ring. PAHs and their derivatives can be either introduced in the atmosphere directly in this form as primary pollutants, or formed by homogenous and heterogeneous oxidation reactions. During the last decades, interest on studying PAH derivatives has increased because derivatives may be more harmful than parent compounds. PAH derivatives have been detected in the atmospheric particulate matter in numerous cities worldwide. PAH derivatives enter living organisms by inhalation, oral ingestion and dermal contact. In vivo and in vitro experiments together with epidemiological studies have shown the toxic effects of PAH derivatives, notably for compounds present in airborne and diesel exhaust particles. Here we review the sources, the mechanisms of formation, the physicochemical properties, the analytical methods, and the toxicological effects of PAHs and their derivatives in airborne particulate matter.     

Chemo-ecological studies on hexactinellid sponges from the Southern Ocean

Hexactinellids (glass sponges) are an understudied class with syncytial organization and poor procariotic associations, thought to lack defensive secondary metabolites. Poriferans, though, are outstanding sources of bioactive compounds; nonetheless, a growing suspicion suggests that many of these chemicals could be symbiont-derived. In Polar latitudes, sponges are readily invaded by diatoms, which could provide natural products. Hexactinellids are typical of deep waters; but in Antarctica, they dominate the upper shelf providing shelter and food supply to many opportunistic mesograzers and macroinvertebrates, which exert strong ecological pressures on them. Aiming to examine the incidence of defensive activities of hexactinellids against consumption, feeding experiments were conducted using their lipophilic fractions. Antarctic hexactinellid and demosponge extracts were tested against the asteroid Odontaster validus and the amphipod Cheirimedon femoratus as putative sympatric, omnivorous consumers. Hexactinellids yielded greater unpalatable activities towards the amphipod, while no apparent allocation of lipophilic defenses was noted. After chemical analyses on the lipophilic fractions from these Antarctic glass sponges, quite similar profiles were revealed, and no peculiar secondary metabolites, comparable to those characterizing other poriferans, were found. Instead, the lipidic compounds 5α(H)-cholestan-3-one and two glycoceramides were isolated for their particular outspread presence in our samples. The isolated compounds were further assessed in asteroid feeding assays, and their occurrence was evaluated for chemotaxonomical purposes in all the Antarctic samples as well as in glass sponges from other latitudes by NMR and MS. Characteristic sphingolipids are proposed as chemical markers in Hexactinellida, with possible contributions to the classification of this unsettled class.