Hybrid expansions for local structural relaxations

A model is constructed in which pair potentials are combined with the cluster expansion method in order to better describe the energetics of structurally relaxed substitutional alloys. The effect of structural relaxations away from the ideal crystal positions, and the effect of ordering is described by interatomic-distance dependent pair potentials, while more subtle configurational aspects associated with correlations of three- and more sites are described purely within the cluster expansion formalism. Implementation of such a hybrid expansion in the context of the cluster variation method or Monte Carlo method gives improved ability to model phase stability in alloys from first-principles.Comment: 8 pages, 1 figur

Effect of an inhaled glucocorticoid on reactive oxygen species production by bronchoalveolar lavage cells from smoking COPD patients

Oxidative stress in the lung is important in the pathogenesis of COPD. Published data indicate that glucocorticoids inhibit blood cells in their capacity to produce reactive oxygen species (ROS). We investigated the effect of Fluticasone propionate (FP) on the ROS production capabilities of pulmonary cells. Bronchoalveolar lavage (BAL) was performed in smoking COPD patients, before and after a six month, placebo-controlled treatment with FP. BAL cells were stimulated with phorbol myristrate acetate (PMA) alone, and together with superoxide dismutase (SOD). From kinetic plots of ferricytochrome-c conversion we calculated the maximal rate of superoxide production: Vmax. We also examined BAL cell subsets and performed correlation analyses on ROS production and relevant clinical determinants. Paired results were obtained from 6 FP- and 9 placebo-treated patients. No significant change of Vmax was found in both patient groups. Also BAL cellularity was unchanged. Correlation analyses showed a significant (inverse) association of Vmax with the number of cigarettes smoked per day. We concluded that a potent inhaled glucocorticoid had no effect on the ROS production capability of BAL cells from smoking COPD patients. Apparently, heavy smoking impaired the ability of alveolar macrophages to produce ROS, which was not further decreased by FP

First-principles equation of state and phase stability for the Ni-Al system under high pressures

The equation of state (EOS) of alloys at high pressures is generalized with the cluster expansion method. It is shown that this provides a more accurate description. The low temperature EOSs of Ni-Al alloys on FCC and BCC lattices are obtained with density functional calculations, and the results are in good agreement with experiments. The merits of the generalized EOS model are confirmed by comparison with the mixing model. In addition, the FCC phase diagram of the Ni-Al system is calculated by cluster variation method (CVM) with both spin-polarized and non-spin-polarized effective cluster interactions (ECI). The influence of magnetic energy on the phase stability is analyzed. A long-standing discrepancy between ab initio formation enthalpies and experimental data is addressed by defining a better reference state. This aids both evaluation of an ab initio phase diagram and understanding the thermodynamic behaviors of alloys and compounds. For the first time the high-pressure behavior of order-disorder transition is investigated by ab initio calculations. It is found that order-disorder temperatures follow the Simon melting equation. This may be instructive for experimental and theoretical research on the effect of an order-disorder transition on shock Hugoniots.Comment: 27 pages, 12 figure

The advantages of an ADHD classification from the perspective of teachers

In Western countries, the number of ADHD diagnoses and medical treatments of children has risen spectacularly over the last decennia, as has the amount of criticism about this trend. Various studies have shown that children receiving an ADHD classification often follow from initial signals that were raised in a school context. Hence, it becomes important to investigate precisely what advantages attach to ADHD classification in educational practice. In this qualitative study, 30 teachers were interviewed about their experiences and views of ADHD. The results suggest that a small number of interviewees sees no advantages to ADHD classification: the classification does not practically help them as teachers, they are familiar with the drawbacks of ADHD classification, and they take issue with the idea of labelling children. The greater number of interviewees, however, suggest ambivalence about ADHD classification: they are aware of its drawbacks while experiencing mainly advantages. According to the interviewees, ADHD classification explains undesirable behaviours and disappointing academic achievement. Classification thereby removes blame from pupils, parents and teachers, and so can be a starting point for productive agreement and collaboration. We will discuss the implications of these findings in the light of the concept of reification, child-centred problematisation and the development of more inclusive education

A new in vitro assay for quantitation of chemotherapy-induced mucositis.

Patients receiving high-dose chemotherapy (HD-CT) are at risk of severe mucositis. Most prevention studies evaluate the degree of mucositis on clinical, and therefore subjective, measurements. The aim of this study was to develop an objective in vitro assay of chemotherapy-induced mucositis. Twelve patients with locally advanced breast carcinoma received HD-CT followed by peripheral stem cell reinfusion. Before and twice weekly after HD-CT, the mucosa was evaluated by an oral washing, a buccal smear and the World Health Organization (WHO) toxicity grading; furthermore, blood leucocyte levels were determined. For the oral washings, the percentage of viable epithelial cells was determined by trypan blue dye exclusion and leucocytes were counted by fluorescence microscopy after incubation with acridine orange. Maturity of buccal cells was assessed by staining buccal smears for morphology according to Papanicolaou (Whitacker D and Williams V, 1994). Eight healthy volunteers served as controls. The mean percentage (+/- s.e.m.) of viable oral epithelial cells was stable in controls (44 +/- 2%). In patients, they increased after HD-CT, which was significant after day 7 compared with pretreatment (P < or = 0.05). In addition, a shift from mature to immature epithelial cells in buccal smears was observed. Oral leucocyte levels were closely correlated with the blood leucocyte counts. The WHO score followed the results of these other evaluations with some delay. The viability of buccal cells obtained by oral washings increases after HD-CT. This is possibly because of desquamation of the upper oral mucosa layer, with a shift from mature to more immature cells. These data can be quantitated, and this assay may therefore be useful in studies aimed at prevention of mucositis

935-38 Restenosis After Coronary Angioplasty is Associated with the Activation Status of Circulating Phagocytes Before Treatment

BackgroundThe purpose of this study was to identify biological risk factors for restenosis after PTCA, in order to predict the long-term outcome of PTCA before treatment.Methods and ResultsTo investigate whether blood granulocytes and monocytes could determine luminal renarrowing after PTCA, several characteristics of these phagocytes were assessed before angioplasty in 32 patients who underwent PTCA of one coronary artery and who had repeat angiograms at six months follow-up. The plasma levels 1L-1β, TNF-α, IL-6, fibrinogen, C-reactive protein and LP(a) before angioplasty were assessed as well. We found that the expression of the membrane antigens CD64, CD66 and CD67 by granulocytes was inversely associated with the luminal renarrowing normalized for vessel size (relative loss) at six months after PTCA. while the production of IL-1β by stimulated monocytes was positively associated with the relative loss. Next. these univariate predictors were corrected for the established clinical risk factors, dilation of the LAD, current smoking and angina class.Multiple linear regression analysis showed that luminal renarrowing could be predicted reliably (R2=0.65; P&lt;0.0001) in this patients group on the basis of the vessel dilated and only two biological risk factors that reflect the activation status of blood phagocytes, i.e., the expression of CD66 by granulocytes and the production of IL-lβ by stimulated monocytes.ConclusionsThe results of the present study indicate that activated blood granulocytes prevent luminal renarrowing after PTCA, while activated blood monocytes promote restenosis. To validate this new finding further study in an independent patients group is required

Prenatal hormones alter antioxidant enzymes and lung histology in rats with congenital diaphragmatic hernia.

Prenatal administration of dexamethasone (Dex) and thyrotropin-releasing hormone (TRH) synergistically enhances lung maturity, but TRH suppresses the antioxidant enzyme activity. Prenatal hormonal therapy improves alveolar surfactant content and lung compliance in rats with congenital diaphragmatic hernia (CDH). In full term neonatal rats with CDH we studied the effects of prenatal Dex or Dex+TRH on antioxidant enzyme activity at birth, on survival, and on lung morphometry after 4 h of ventilation with 100% O2. CDH was induced by administration of 2,4-dichlorophenyl-p-nitro-phenylether (Nitrofen) on gestational day 10. Dex+TRH-treated CDH rats had lower activity of glutathione reductase after birth than did sham-treated CDH pups. Dex-treated and sham-treated pups had similar antioxidant enzyme activity. Hormonal treatment did not change survival during ventilation. The average airspace volume increased in Dex-treated CDH pups after ventilation, with a small synergistic effect after addition of TRH. On the basis of our findings, we speculate that prenatal administration of Dex is the best choice to improve lung maturity and airspace volume in CDH patients

Quality of life and illness perception in working and sick-listed chronic RSI patients

OBJECTIVE: To study differences between working and sick-listed chronic repetitive strain injury (RSI) patients in the Netherlands with respect to indices of quality of life and illness perception. METHODS: In a cross-sectional design, one questionnaire was sent to all 3,250 members of the national RSI patient association. For descriptive purposes, demographics, work status and complaint-related variables such as severity, type, duration, and extent of complaints were asked for. Indices of quality of life were assessed through seven SF-36 subscales (physical (role) functioning, emotional role functioning, social functioning, pain, mental health and vitality). A work-ability estimate and VAS scales were used to assess complaint-related decrease in quality of life. Illness perception was assessed through the brief illness perception questionnaire (IPQ-B). Working patients and sick-listed patients were identified. Tests between the two independent groups were performed and P-values < 0.01 were considered significant. RESULTS: Data from 1,121 questionnaires were used. Two-thirds of the respondents worked and one-third were sick-listed. Average duration of complaints was over 5 years in both groups. The sick-listed patients reported significantly more severe and extensive complaints than did the working patients. In addition, sick-listed patients reported significantly poorer mental health, physical (role) functioning, emotional role functioning, pain, vitality, and work-ability. With respect to illness perception, both groups showed the same concerns about their complaints, but sick-listed patients had significantly more distorted perceptions in their emotional response, identity, treatment control, personal control, timeline, and life consequences. Complaint-related decrease in quality of life was 31% in the working patients and 49% in the sick-listed patients. CONCLUSION: The study found a greater number and severe complaints among sick-listed chronic RSI patients and a considerably decreased quality of life because of their complaints. These findings may allow for a better treatment focus in the futur

Scavenging of reactive oxygen species leads to diminished peritoneal tumor recurrence

Previously, we demonstrated that RBCs inhibit the recurrence of perioperatively spilled tumor cells. The aim of this study was to identify on which RBC component(s) the inhibitory effect is based. By using a cell-seeding model in rats, the effect of RBC-related antioxidant scavengers [hemoglobin, catalase, and superoxide dismutase (SOD)] on peritoneal tumor recurrence was investigated. i.p. injection of hemoglobin caused 45% more tumor load (P < 0.0001). At least 40% inhibition of tumor recurrence was achieved with the use of catalase or SOD (P < 0.05). Combining SOD and catalase did not lead to additional inhibition of tumor recurrence. Inhibition of the overwhelmin