Changes in middle cerebral artery velocimetry of fetuses diagnosed postnatally with mild or moderate hemolytic disease.

OBJECTIVES: To determine the longitudinal trends of middle cerebral artery peak systolic velocity (MCA PSV) in fetuses with mild or moderate hemolytic disease according to the need for postnatal therapy. DESIGN: Prospective cohort study. SETTING: University referral center. SAMPLE: Twenty-three fetuses from singleton alloimmunized pregnancies. METHODS: Serial measurements of MCA PSV were performed. After delivery, newborns were grouped by the need for postnatal management into mild hemolytic disease, which required no or only phototherapy (n = 14, group 1), and moderate hemolytic disease, where postnatal top-up or exchange transfusions were required (n = 9, group 2). MAIN OUTCOME MEASURES: Serial Doppler MCA PSV data transformed to multiples of the median, analyzed with linear regression and exponential models. RESULTS: We performed 83 measurements in group 1: 3-8 per fetus; mean GA at inclusion, 23 weeks and 65 measurements in group 2: 4-15 per fetus; mean GA at inclusion, 22 weeks. The estimated mean slopes of the MCA PSVs increased with the degree of postnatal therapy required (group 1: MCA PSV = 0.003 GA + 1.298; group 2: MCA PSV = 0.035 GA + 0.436). The relative average increments (RAI) were 4.7% and 7.1%, respectively. The two groups exhibited significant differences in mean slope and RAI (p<0.05). CONCLUSIONS: Fetuses that required postnatal transfusions due to hemolytic disease showed an enhanced progressive increase in MCA PSVs compared to those without transfusion requirement. This information might enable their identification during pregnancy.

Multi-instrumental Analysis of Tissues of Sunflower Plants Treated with Silver(I) Ions - Plants as Bioindicators of Environmental Pollution.

The aim of this work is to investigate sunflower plants response on stressinduced by silver(I) ions. The sunflower plants were exposed to silver(I) ions (0, 0.1, 0.5,and 1 mM) for 96 h. Primarily we aimed our attention to observation of basic physiologicalparameters. We found that the treated plants embodied growth depression, coloured changes and lack root hairs. Using of autofluorescence of anatomical structures, such aslignified cell walls, it was possible to determine the changes of important shoot and rootstructures, mainly vascular bungles and development of secondary thickening. Thedifferences in vascular bundles organisation, parenchymatic pith development in the rootcentre and the reduction of phloem part of vascular bundles were well observable.Moreover with increasing silver(I) ions concentration the vitality of rhizodermal cellsdeclined; rhizodermal cells early necrosed and were replaced by the cells of exodermis.Further we employed laser induced breakdown spectroscopy for determination of spatialdistribution of silver(I) ions in tissues of the treated plants. The Ag is accumulated mainlyin near-root part of the sample. Moreover basic biochemical indicators of environmentalstress were investigated. The total content of proteins expressively decreased withincreasing silver(I) ions dose and the time of the treatment. As we compare the resultsobtained by protein analysis - the total protein contents in shoot as well as root parts - wecan assume on the transport of the proteins from the roots to shoots. This phenomenon canbe related with the cascade of processes connecting with photosynthesis. The secondbiochemical parameter, which we investigated, was urease activity. If we compared theactivity in treated plants with control, we found out that presence of silver(I) ions markedlyenhanced the activity of urease at all applied doses of this toxic metal. Finally we studiedthe effect of silver(I) ions on activity of urease in in vitro conditions.

Detection of lead in Zea mays by dual-energy X-ray microtomography at the SYRMEP beamline of the ELETTRA synchrotron and by atomic absorption spectroscopy.

This study is related to the application of the X-ray dual-energy microradiography technique together with the atomic absorption spectroscopy (AAS) for the detection of lead on Zea mays stem, ear, root, and leaf samples. To highlight the places with lead intake, the planar radiographs taken with monochromatic X-ray radiation in absorption regime with photon energy below and above the absorption edge of a given chemical element, respectively, are analyzed and processed. To recognize the biological structures involved in the intake, the dual-energy images with the lead signal have been compared with the optical images of the same Z. mays stem. The ear, stem, root, and leaf samples have also been analyzed with the AAS technique to measure the exact amount of the hyperaccumulated lead. The AAS measurement revealed that the highest intake occurred in the roots while the lowest in the maize ears and in the leaf. It seems there is a particular mechanism that protects the seeds and the leaves in the intake process.

Simplified description of optical forces acting on a nanoparticle in the Gaussian standing wave.

We study the axial force acting on dielectric spherical particles smaller than the trapping wavelength that are placed in the Gaussian standing wave. We derive analytical formulas for immersed particles with relative refractive indices close to unity and compare them with the numerical results obtained by generalized Lorenz-Mie theory (GLMT). We show that the axial optical force depends periodically on the particle size and that the equilibrium position of the particle alternates between the standing-wave antinodes and nodes. For certain particle sizes, gradient forces from the neighboring antinodes cancel each other and disable particle confinement. Using the GLMT we compare maximum axial trapping forces provided by the Gaussian standing-wave trap (SWT) and single-beam trap (SBT) as a function of particle size, refractive index, and beam waist size. We show that the SWT produces axial forces at least ten times stronger and permits particle confinement in a wider range of refractive indices and beam waists compared with those of the SBT.