Extreme leukoreduction of major histocompatibility complex class II positive B cells enhances allogeneic platelet immunity

In a murine model of platelet alloimmunization, we examined the definitive role that mononuclear cells (MC) have in modulating platelet immunity by using platelets from severe combined immunodeficient (SCID) mice. CB.17 (H-2(d)) SCID or BALB/c (H-2(d)) mouse platelets were transfused weekly into fully allogeneic CBA (H-2(k)) mice and antidonor antibodies measured by flow cytometry. MC levels in BALB/c platelets were 1.1 +/- 0.6/microL and SCID mouse platelets could be prepared to have significantly lower (<0. 05/microL) MC numbers. Transfusions with 10(8) BALB/c platelets (containing approximately 100 MC/transfusion) stimulated IgG antidonor antibodies in 100% of the recipients by the fifth transfusion, whereas 10(8) SCID mouse platelets (containing approximately 5 MC/transfusion) stimulated higher-titered IgG alloantibodies by the second transfusion. When titrations of BALB/c peripheral blood MC were added to the SCID mouse platelets, levels approaching 1 MC/microL reduced SCID platelet immunity to levels similar to BALB/c platelets. Characterization of the alloantibodies showed that the low levels of MC significantly influenced the isotype of the antidonor IgG; the presence of 1 MC/microL was associated with induction of noncomplement fixing IgG1 antidonor antibodies, whereas platelet transfusions, devoid of MC (<0. 05/microL), were responsible for complement-fixing IgG2a production. When magnetically sorted defined subpopulations of MC were added to the SCID platelets, major histocompatability complex (MHC) class II positive populations, particularly B cells, were found to be primarily responsible for the reduced SCID mouse platelet immunity. The presence of low numbers of MC within the platelets was also associated with an age-dependent reduction in platelet immunogenicity; this relationship however, was not observed with SCID mouse platelets devoid of MC. The results suggest that a residual number of MHC class II positive B cells within allogeneic platelets are required for maximally reducing alloimmunization.     

Influence of Gating System,Sand Grain Size,and Mould Coating on Microstructure and Mechanical Properties of Thin-Wall Ductile Iron

 In this study, the effect of gating systems, mould coating and sand grain size on metallurgical and mechanical properties of TWDI casting were investigated. Two different gating systems; stepped and tapered runners, were used to cast strip samples. The thicknesses of the samples cast were 2.3, 3.3, 4.5, 5.4, 6.5, 7.5 and 8.5 mm. The samples were cast in CO2/silicate process moulds of two different sand grain sizes of 151 and 171 according to the AFS standard. To assess the effect of mould coat on the properties of TWDI, half of the moulds were coated with graphite-based zircon whilst the rest were left uncoated. The carbon equivalent (CE) of the molten metal prepared was 4.29% and poured at the temperatures of 1450°C. The microstructure of the cast specimens was analyzed by optical and scanning electron microscopes. Clemex Image Analyzer (CIA) was used to evaluate graphite nodule count, graphite nodules area fraction, roundness and diameter of the nodules of the TWDI cast samples. Brinell hardness and tensile tests were also conducted on all the samples. The results show that by using stepped runner gating system with uncoated and coarse sand grain size mould, roundness and graphite nodule counts decrease. However, graphite nodules diameter and area fraction increase. The results also show that finer sand grain size and coated mould produce longer distance of molten metal travel.     

Tidal volume effects on surfactant treatment responses with the initiation of ventilation in preterm lambs

We hypothesized that initiation of ventilation in preterm lambs with high volumes would cause lung injury and decrease the subsequent response to surfactant treatment. Preterm lambs were randomized to ventilation for 30 min after birth with 5 ml/kg (VT5), 10 ml/kg (VT10), or 20 ml/kg (VT20) tidal volumes and then ventilated with approximately 10 ml/kg tidal volumes to achieve arterial PCO2 values of approximately 50 Torr to 6 h of age. VT20 lambs had lower compliances, lower ventilatory efficiencies, higher recoveries of protein, and lower recoveries of surfactant in alveolar lavages and in surfactant that had decreased compliances when tested in preterm rabbits than VT5 or VT10 lambs. Other lambs randomized to treatment with surfactant at birth and ventilation with 6, 12, or 20 ml/kg tidal volumes for 30 min had no indicators of lung injury. An initial tidal volume of 20 ml/kg decreased the subsequent response to surfactant treatment, an effect that was prevented with surfactant treatment at birth.     

Recurrent gains of 1q, 8 and 12 in the Ewing family of tumours by comparative genomic hybridization

Comparative genomic hybridization (CGH) was used to detect copy number changes of DNA sequences in the Ewing family of tumours (ET). We analysed 20 samples from 17 patients. Fifteen tumours (75%) showed copy number changes. Gains of DNA sequences were much more frequent than losses, the majority of the gains affecting whole chromosomes or whole chromosome arms. Recurrent findings included copy number increases for chromosomes 8 (seven out of 20 samples; 35%), 1q (five samples; 25%) and 12 (five samples; 25%). The minimal common regions of these gains were the whole chromosomes 8 and 12, and 1q21-22. High-level amplifications affected 8q13-24, 1q and 1q21-22, each once. Southern blot analysis of the specimen with high-level amplification at 1q21-22 showed an amplification of FLG and SPRR3, both mapped to this region. All cases with a gain of chromosome 12 simultaneously showed a gain of chromosome 8. Comparison of CGH findings with cytogenetic analysis of the same tumours and previous cytogenetic reports of ET showed, in general, concordant results. In conclusion, our findings confirm that secondary changes, which may have prognostic significance in ET, are trisomy 8, trisomy 12 and a gain of DNA sequences in 1q.     

On the statistical modelling of coronary arteriographic data: dynamics of coronary atherosclerosis related to systemic and focal parameters. REGRESS Study Group. Regression Growth Evaluation Statin Study

Existing methods to analyse data from repeated arteriographic progression/regression studies are restrictive and do not fully explore the dynamics of coronary artherosclerosis. We present a new approach making a distinction between new occlusions, new lesions, and growth of existing lesions. Random effect models, based on the logistic, the Poisson, and the normal distribution are proposed with correlation depending on distance. The data from the Regression Growth Evaluation Statin Study (REGRESS) are used to validate the model. Lipid lowering treatment of pravastatin resulted in less growth of existing lesions and fewer new lesions than when placebo was given. Fewer new lesions were found in segments influenced by percutaneous transluminal coronary angioplasty (PTCA) than in segments not influenced by PTCA. Similarly, the growth of lesions influenced by PTCA was smaller than lesions not influenced by PTCA. More new occlusions were found in segments influenced by coronary arterial bypass grafting (CABG) than in segments not influenced by CABG, but 98 per cent of the new occlusions were located proximal to the bypass anastomosis. Similarly, existing lesions proximal to the bypass anastomosis showed larger growth (p < 0.001). We conclude that our new approach for analysing the arteriographic data from repeated coronary arteriographic studies appeared a fruitful way to analyse the dynamics of coronary atherosclerosis.     

A DNA-binding element for a steroid receptor-binding factor is flanked by dual nuclear matrix DNA attachment sites in the c-myc gene promoter

The receptor-binding factor (RBF) for the avian oviduct progesterone (Pg) receptor (PR) has previously been shown to be a unique 10-kDa nuclear matrix protein that generates high affinity PR-binding sites on avian DNA. This paper describes the use of Southwestern blot and DNA gel shift analyses with RBF protein to identify a minimal 54-base pair RBF-binding element in the matrix-associated region (MAR) of the Pg-regulated c-myc gene promoter. This element contains a 5'-GC-rich domain and a 3'-AT-rich domain, the latter of which has a homopurine/homopyrimidine structure. The gel shift assays required the generation of an RBF-maltose fusion protein (RBF-MBP), which specifically binds this element and is supershifted when the anti-RBF polyclonal antibody is added. Computer analysis of the full-length amino acid sequence for RBF predicts a DNA-binding motif involving a beta-sheet structure at the N-terminal domain. Southern blot analyses using nuclear matrix DNA suggests that there are dual MAR sites in the c-myc promoter, which flank an intervening domain containing the RBF element. The co-transfection of this MAR sequence, containing the RBF element and cloned into a luciferase reporter vector, together with an RBF expression vector construct, into steroid treated human MCF-7 cells, results in a decrease of the c-myc promoter activity relative to control transfections containing only the parent vector of the RBF expression construct. These data suggest that a unique chromatin/nuclear matrix structure, composed of the RBF-DNA element complex which is flanked by nuclear matrix attachment sites, serves to bind the PR and repress the c-myc promoter.