Diagnosis,surveillance, and treatment of the anemic fetus using middle cerebral artery peak systolic velocity measurement

The in utero course of the anemic fetus has improved dramatically, owing to early diagnosis and cordocentesis transfusion. In utero invasive procedures such as amnio- and cordocentesis have become important modalities in the evaluation and treatment of anemic fetuses. However, they carry risks for both the mother and fetus. A valid and sensitive noninvasive means of following the anemic fetus is the evaluation of changes in the middle cerebral artery peak systolic flow velocity (MCA-PSV). This is a sensitive tool for both the evaluation of fetal anemia and response to treatment. Intracerebral vessels respond earliest to the fetal anemic state, and are readily accessible for ultrasound examination. We describe the methodology and evolving clinical applications of MCA-PSV measurement in the fetus, through an overview of the literature describing the development and application of MCA-PSV measurement in fetuses at risk of fetal anemia of various immune and nonimmune etiologies, illustrated by index cases from our center. MCA-PSV measurement is essential in the diagnosis, evaluation, and management of cases of fetal anemia. The use of this modality lessens the need for invasive procedures. The method is readily accessible and should be integrated into the repertoire of all obstetric ultrasound centers. Copyright © 2006 John Wiley & Sons, Ltd.     

Habitat selection by breeding waterbirds at ponds with size-structured fish populations

Fish may significantly affect habitat use by birds, either as their prey or as competitors. Fish communities are often distinctly size-structured, but the consequences for waterbird assemblages remain poorly understood. We examined the effects of size structure of common carp (Cyprinus carpio) cohorts together with other biotic and abiotic pond characteristics on the distribution of breeding waterbirds in a seminatural system of monocultured ponds, where three fish age classes were separately stocked. Fish age corresponded to a distinct fish size gradient. Fish age and total biomass, macroinvertebrate and amphibian abundance, and emergent vegetation best explained the differences in bird density between ponds. Abundance of animal prey other than fish (aquatic macroinvertebrates and larval amphibians) decreased with increasing carp age in the ponds. Densities of ducks and smaller grebes were strongly negatively associated with fish age/size gradient. The largest of the grebes, the piscivorous great crested grebe (Podiceps cristatus), was the only species that preferred ponds with medium-sized fish and was positively associated with total fish biomass. Habitat selection by bitterns and most rallids was instead strongly influenced by the relative amount of emergent vegetation cover in the ponds. Our results show that fish size structure may be an important cue for breeding habitat choice and a factor affording an opportunity for niche diversification in avian communities.     

NMR study of the humification process during sewage sludge treatment

Humic acids, extracted from sludge at the biologic-mechanical sewage treatment plant in Jastrzebie Zdroj, have been investigated by means of (1)H, (13)C and (31)P NMR spectroscopy. Sludge samples for studies were taken from the primary settling tank, the nitrification chamber, the digestion chamber and the sludge drying beds. The (1)H NMR analysis of humic acid extracted from sludge at various stages of sewage treatment confirmed the presence of the functional groups that are characteristic for humic substances, and the analysis showed changes in their relative intensities. The (13)C NMR indicated that the aromatisation of the humic acid increased during sewage treatment. Moreover, the analysis of the (31)P NMR spectra allowed us to observe the changes in the phosphorus groups of the studied humic acids.     

Assessment of herbaceous plant habitats in water-constrained environments: predicting indirect effects with fuzzy logic

Herbaceous plant production plays a key role in determining the function of rangeland ecosystems in the semi-arid and Mediterranean regions. Therefore, assessment of herbaceous plant habitats is important for understanding the ecosystem functioning in these regions and for applied purposes, such as range management and land evaluation. This paper presents a model to assess herbaceous plant habitats in a basaltic stony environment in a Mediterranean region. The model is based on geographic information systems (GIS), remote sensing and fuzzy logic, while four indirect variables, which represent major characteristics of herbaceous habitats, are modeled: rock cover fraction; wetness index (WI); soil depth; and slope orientation (aspect). A linear unmixing model was used to measure rock cover on a per pixel basis using a Landsat TM summer image. The wetness index and local aspect were determined from digital elevation data with 25 m × 25 m pixel resolution, while soil data were gathered in a field survey. The modeling approach adopted here is process-based and assumes that water availability plays a crucial role in determining herbaceous plant production in Mediterranean and semi-arid environments. The model rules are based on fuzzy logic and are written based on the hypothesized water requirements of the herbaceous vegetation. The results show that on a polygon basis there is positive agreement between the model proposed here and previous mapping of the herbaceous habitats carried out in the field using traditional methods. Intrapolygon tests show that the use of a continuous raster data model and fuzzy logic principles provide an added value to traditional mapping. Moreover, herbaceous biomass measurements at two time intervals—mid- and peak winter season—corresponded with the habitat assessment predictions achieved using a new scenario that is proposed in this research. This scenario suggests that rockiness increases herbaceous production on south-facing slopes, while in other slope aspects the rock cover has lower impact on herbaceous growth. Due to its simplicity, the model suggested here can be used by planners and managers, to adjust range activities over large areas. The process-based approach should allow adaptation of the model to other regions more effectively than models that were formulated on a purely empirical basis. The model could also be used to study the relationship between water availability and ecosystem productivity on a regional scale.     

Response of fluctuating asymmetry to arsenic toxicity: support for the developmental selection hypothesis

The effect of exposure to sodium arsenite during development was tested on adult fluctuating asymmetry (FA) in sternopleural bristle number, bristle number, body size and survivorship in Drosophila melanogaster. Three genetic strains of flies were used, CT-106, PVM and Oregon-R, and arsenite concentrations ranged from relatively mild, sub-lethal doses, to concentrations with pronounced negative effects on survivorship. At arsenite concentrations of 1.0 and 0.125 mM, mortality was on average 38% greater than in controls, and surviving flies emerged significantly smaller and had fewer bristles than controls. Neither the effect of arsenite or the genotype x environment interaction on asymmetry were significant. However, given the high mortality, any increase in FA could have been masked by the outcome of developmental selection against developmentally unstable phenotypes. We tested for this effect by contrasting FA values between (1) flies reared at the highest concentrations used previously, (2) flies reared at sub-lethal dosage, and (3) controls. Positional fluctuating asymmetry (PFA), which is expected to be a sensitive indicator of underlying developmental stability, was significantly reduced among flies reared at the highest concentration, and at which flies suffered significant mortality. Moreover, the slope of the regression relating mean PFA to emergence per bottle was significantly positive. These data support the hypothesis that developmental selection occurred in this experiment, and that the expected positive relationship between asymmetry and stress may be altered when the stressor eliminates individuals from the population. In contrast, FA of flies reared at sub-lethal dosage did not differ from that in controls, a result that fails to support the hypothesis that arsenite disrupts developmental stability. Our results call for caution in FA-based biomonitoring, especially of potentially lethal forms of stress, because in the presence of developmental selection, and under the common assumption that FA should increase under stress, erroneous conclusions may be drawn about the health and well being of a population. It is suggested that FA-based biomonitoring efforts integrate the use of FA with other bioindicators, and experimentally validate any expected FA-stress relationship before attempting to infer the presence of environmental stress.