Pharmacokinetics of the PDGF-antagonist trapidil in patients with and without renal impairment

BACKGROUND: From July 1989 to February 1996, 130 patients underwent stereotactic radiosurgery. We report the results of the first 50 patients eligible for a minimum of three years of follow-up. METHODS: Twenty women and 30 men, (mean age: 37.5 years) were treated by dynamic rotation on a 6 MV linear accelerator. Prior treatment was embolization in seventeen, surgery in three and embolization and surgery in six. All had DSA and enhanced CT scanning, while some had MRI. Forty-seven treatments used a single isodose. Restricting eloquent normal tissue to 15 Gy, margin doses (at 50-90% isodose) were 12 Gy (one patient); 15 Gy (sixteen patients); 20 Gy (31 patients); 25 Gy (two patients). Maximum diameters were: < 1.5 cm (12 patients); < 2.0 cm (nine patients); < 2.5 cm (twelve patients); < 3.0 cm (thirteen patients; 3.0 cm (four patients). RESULTS: Forty-five patients were evaluable at three years, with thirty-nine having angiography. Twenty-five had angiographically confirmed obliterations; two had parenchymal AVMs obliterated but with residual dural components; four had MRI evidence of obliteration (refused angiography). One patient acutely had a seizure; one patient (with hemorrhages, resection, and embolizations preceding two applications of radiosurgery, separated by 3.5 years) had worsening of memory. CONCLUSIONS: Our uncorrected (five patients unevaluable at three years) and corrected angiographically confirmed obliteration rates are 54% and 60% respectively. Our follow-up (98% accounting of cohort; 78% angiographic rate) and explicit derivation of denominators help delineate the efficacy of radiosurgery at these doses.     

Understanding pregnant women's decision making concerning prenatal screening.

Objective: This study is aimed at enhancing understanding prenatal screening decision making through testing a hypothesized decision model based on decision theory and health behavior theory. Design: We obtained questionnaires from 1,666 pregnant women who were offered prenatal screening for Down's syndrome. Path analysis (using LISREL) resulted in a final model with reasonable model fit, which was verified by split-sample cross-validation. Main outcome measures: These included perceived probability, perceived severity, attitude toward termination, response efficacy, attitude toward prenatal screening, subjective norm, child-related anxiety, and intention to undergo prenatal screening. Results: Attitude toward termination of pregnancy, perceived test efficacy, and subjective norm regarding the desirability of having prenatal screening determined a woman's attitude toward having a prenatal test. Anxiety was influenced by perceived risk and perceived severity of having a child with Down's syndrome, and by subjective norm, but this appeared to be a weak predictor of intention to test. Pregnant women with a positive attitude toward prenatal screening, and who perceived a subjective norm in favor of undergoing prenatal screening, showed a greater intention to have prenatal screening done. Conclusion: These findings suggest that more attention should be paid toward the values and social context of pregnant women during the counseling process. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Isolated cranial nerve palsies in multiple sclerosis

During a 10 year period 24 patients with definite multiple sclerosis with isolated cranial nerve palsies were studied (third and fourth nerve: one patient each, sixth nerve: 12 patients, seventh nerve: three patients, eighth nerve: seven patients), in whom cranial nerve palsies were the presenting sign in 14 and the only clinical sign of an exacerbation in 10 patients. MRI was carried out in 20 patients and substantiated corresponding brainstem lesions in seven patients (third nerve: one patient, sixth nerve: four patients, eighth nerve: two patients). Additional abnormal findings of electro-oculography, or masseter reflex, or blink reflex, or combinations of these were found in 20 patients and interpreted in favour of a brainstem lesion at the level of the respective cranial nerve. In 11 of 14 patients with isolated cranial nerve palsies as the presenting sign of multiple sclerosis, dissemination in space was documented by MRI, and in the remaining three by evoked potentials. In patients with multiple sclerosis with isolated cranial nerve palsies, MRI is the most sensitive method of documenting dissemination in space and electrophysiological testing the most sensitive at disclosing brainstem lesions.     

Attack upon the cladding of oxide fuel pins by fuel and fission products

In parallel with post-irradiation examinations, a comprehensive out-of-pile experimental programme has been performed to determine the most important fission product reactions with four austenitic stainless steels at different oxygen potentials. Single as well as groups of fission products (simulated burn-up systems) have been used. Only the elements cesium, iodine and tellurium cause dangerous reactions with the cladding of an oxide fuel pin. The others are either not reactive or produced in such small quantities that their attack on the cladding is insignificant. Molybdenum is often found in the reaction zone of an irradiated oxide pin. However, according to our out-of-pile results it does not look as if molybdenum is a dangerous fission product. A decisive factor for the occurrence of reactions with the cladding is the oxygen potential in the fuel pin. As long as the O/M ratio of the fuel is markedly below 2.00, there are no dangerous reactions, neither with cesium nor with tellurium and iodine. The post-irradiation investigations (burn-up 1 to 10 at %) have shown that the cladding attack below 750 °C is most dependent on the inner wall temperature. Other factors, including fuel density, rod power and burn-up, seem to play a minor role. A noticeable reduction of the cladding attack was observed when the initial O/M ratio of the fuel was less than 1.98. A kinetic evaluation of some of the reactions observed in the out-of-pile tests has been attempted. At temperatures above 700 °C, the influence of temperature decreases markedly and the fission product concentration in the fuel becomes more important. There are indications that this also holds true for in-pile conditions.     

Surface,grain boundary and interfacial energies in UO2 and UO2-Ni

Using the multiphase equilibrium method for determination of wetting angles we determined the surface and grain boundary energies of polycrystalline stoichiometric UO₂ at 1500, 1750 and 1900°C. The data of the surface energy of UO₂ agree with most of the published results. Linear temperature functions were obtained by extrapolation for both quantities between 0 K and the melting point of UO₂. Measurements of the interfacial energy in the UO₂-Ni system yielded a linear dependence on temperature in the range investigated.     

Investigations on UAlx-Al dispersion fuels for high-flux reactors

The paper outlines the preparation of $\text{UAl}{}_{\mathrm{x}}\text{-Al}$ dispersion fuel plates for thermal high-flux reactors. The work described includes the preparation of UAl₂, UAl₃ and UAl₄ compounds by induction melting and their processing to Al-clad fuel plates using the picture-frame technique. Induction melting in alumina crucibles and subsequent homogenisation can be used to produce relatively homogeneous $\text{UAl}{}_{\mathrm{x}}$ compounds. After comminution to a predetermined size range and blending with Al, the pressed compacts can be rolled into Al-clad fuel plates. UAl₃ and UAl₂ compounds react with Al forming UAl₄. The reactions begin at about 673 K, and have an activation energy of 52.6 and 42.6 kcal/mol, respectively. The measured properties of the dispersions and UAl-phases such as thermal expansion, thermal and electrical conductivity, tensile strength, microhardness and hot hardness are affected by the concentration of the dispersed phase and can be explained in the light of existing theoretical models. Due to its potential as a high-flux reactor fuel with higher uranium content the preparation and properties of UAl₂-Al dispersions as well as the preliminary data about their stability under irradiation may be of particular interest.     

Overland Water Flow and Solute Transport: Model Development and Field-Data Analysis

The application of plant nutrients with irrigation water is an efficient and cost-effective method for fertilizer application to enhance crop production and reduce or eliminate potential environmental problems related to conventional application methods. In this study, a combined overland water flow and solute transport model for analysis and management of surface fertigation/chemigation is presented. Water flow is predicted with the well-known Saint-Venant’s equations using a control volume of moving cells, while solute transport is modeled with the advection-dispersion equation. The 1D transport equation was solved using a Crank-Nicholson finite-difference scheme. Four, large-scale, field experiments were conducted on blocked-end and free draining furrows to calibrate and verify the proposed model. The results showed that application of solute during the entire irrigation event, or during the second half of the irrigation for blocked end conditions with appropriate inflow rates, produced higher solute uniformity than application of solute during the first half of the irrigation event. Measured fertilizer distribution uniformity of the low quarter ranged from 21 to 76% while fertilizer distribution uniformity of the low half values varied between 62 to 87%. The model was subsequently applied to the experimental data; results showed good agreement with all field data. Water balance errors for the different experiments varied from 0.004 to 1.8%, whereas fertilizer mass balance errors ranged from 1.2 to 3.6%. A sensitivity analysis was also performed to assess the effects of longitudinal dispersivity parameter on overland solute concentrations. A value of 10 cm for dispersivity provided a reasonable fit to the experimental data.     

Screening of fungi for the biological modification of hard coal and coal derivatives

A biotechnological depolymerization of hard coal is being attempted with basidiomycetous fungi native to timber, plant residues, and soil, and with microfungi of lignite sources and contaminated soil. The coal materials such as powdered or hydrogenated hard coal (asphaltene) were aseptically exposed to fungal pure cultures in a four-step screening system. Agar surface cultures were examined for softening and erosion of the coal particles, and for alterations in the asphaltene films fixed to plastic chips and silica gel. From the shake cultures, both the culture fluid and the coal or asphaltene sediments were separately collected and processed by photospectrometry, gel permeation chromatography, combined gas chromatography-mass spectrometry, and IR spectrometry.

Of the 243 fungal strains tested to date, four were reactive on coal materials and asphaltene. Two basidiomycetes (Coriolus hirsutus [Wulf.] Quel.; Coprinus sclerotiger Watl.) eroded hard coal particles, while another basidiomycetous strain (Agrocybe semiorbicularis [Bull.:Fr.]) separated the asphaltene film from its plastic carrier. The hyphomycete Trichoderma spec. strain AB2 caused alterations in the IR spectrum of asphaltene.     

The formation of nodular structures in the top layer of ultrafiltration membranes

The formation of nodular structures in the top layer of ultrafiltration membranes is considered. A critical review of mechanisms described in the literature is given. Flat-sheet poly(ether sulfone) membranes and hollow-fiber poly(ether sulfone)/polyvinylpyrrolidone membranes were made by coagulation of a polymer solution in a nonsolvent medium under different circumstances. From these experiments, a number of empirical rules are found to describe the resulting morphology of the top layer. A new mechanism for the formation of a nodular structure is proposed. It is based on the small diffusion coefficient of the polymer molecules compared to the diffusion coefficient of solvent and nonsolvent combined with a high degree of entanglement of the polymer network. For unstable compositions, phase separation will proceed by growth in amplitude of concentration fluctuations. The rapid diffusional exchange of solvent for nonsolvent in the top layer leads to vitrification of the maxima of the concentration fluctuations that form the nodules. Complete disentanglement of the polymer chains between the nodules is not reached, which explains the small pores and the low porosity of ultrafiltration membranes. © 1994 John Wiley & Sons, Inc.     

Investigation of MWCNT addition into poly-dimethylsiloxane-based coatings

The purpose of this work is to investigate the effects on the properties of poly-dimethylsiloxane-based coatings with the incorporation of multi-walled carbon nanotubes (MWCNT). For this reason, two types of MWCNT were examined (pristine and functionalised with carboxyl groups). An optimised dispersion method was employed to synthesise coatings with different wt-% concentrations of CNT, using different solvents. The morphology of the nanocomposite coatings was studied under optical and scanning electron microscopy. Moreover, their hydrophobic/hydrophilic behaviour was investigated by contact angle measurements. Furthermore, nanoindentation and nanoscratch tests were conducted to evaluate the nanomechanical properties. The results revealed an optimal threshold concentration of 0.1?wt-% in CNT that combines both acceptable dispersibility and mechanical enhancement of the composite coating. It was proven that the increase in CNT content deteriorates the surface and mechanical properties of the coatings.