Adhesion of endothelial cells and adsorption of serum proteins on gas plasma-treated polytetrafluoroethylene

From in vitro experiments it is known that human endothelial cells show poor adhesion to hydrophobic polymers. The hydrophobicity of vascular prostheses manufactured from Teflon® or Dacron® may be the reason why endothelialization of these grafts does not occur after implantation in humans. We modified films of polytetrafluoroethylene (Teflon®) by nitrogen plasma and oxygen plasma treatments to make the surfaces more hydrophilic. Depending on the plasma exposure time, modified polytetrafluoroethylene surfaces showed water-contact angles of 15–58°, versus 96° for unmodified polytetrafluoroethylene. ESCA measurements revealed incorporation of both nitrogen- and oxygen-containing groups into the polytetrafluoroethylene surfaces, dependent on the plasma composition and exposure time. The thickness of the modified surface layer was ~1 nm. The adhesion of cultured human endothelial cells from 20% human serum-containing culture medium to modified polytetrafluoroethylene surfaces with contact angles of 20–45° led to the formation of a monolayer of cells, which was similar to the one formed on tissue culture polystyrene, the reference surface. This was not the case when endothelial cells were seeded upon unmodified polytetrafluoroethylene. Surface-modified expanded polytetrafluoroethylene prosthesis material (GORE TEX® soft tissue) also showed adhesion of endothelial cells comparable to cell adhesion to the reference surface. The amounts of serum proteins, including fibronectin, adsorbed from serumcontaining medium to modified polytetrafluoroethylene surfaces were larger than those adsorbed to unmodified polytetrafluoroethylene. Moreover, the modified surfaces probably allow the exchange of adsorbed serum proteins with cellular fibronectin

Polymerization of ethylene oxide using yttrium isopropoxide

Well defined poly(ethylene oxide)s were prepared using yttrium isopropoxide as an initiator. End group analysis using 1H- and 13C NMR spectroscopy revealed that only polymers with isopropyl ether and hydroxyl end groups were produced. The molecular weight is controlled by the initial amount of initiator added and low polydispersity polymer (Mw/Mn ≈ 1.1) was isolated. Sequential polymerization indicated the suitability of this initiator for macromolecular engineering

Poly(dimethylsiloxane)-poly(ethylene oxide)-heparin block copolymers II: Surface characterization and in vitro assessments

Amphiphilic block copolymers containing poly(dimethylsiloxane), poly(ethylene oxide), as well as heparin-coated glass beads and tubes were evaluated for the amounts and activities of surface-immobilized heparin. Because the amphiphilic copolymer system is thermodynanmcally predicted to demonstrate low-energy phase enrichment on the surfaces of aircast films, studies were also undertaken to understand the in vitro results. Solvent-cast copolymer films have a heterogeneous microphase-separated structure according to transmission electron micrographs. Wilhelmy plate contact angle analysis indicates significant surface restructuring occurs upon hydration. Attenuated total reflectance infrared spectroscopy studies of the desiccated and hydrated films at two different sampling depths show compositional heterogeneity as a function of depth, as well as near surface restructuring allowing surface enrichment of the high-energy segments following contact with water. Significant concentrations of heparin are detected on the surface of these coatings by toluidine blue assays. In addition, a portion of the surface-bound heparin maintains its original bioactivity as determined by recalification times, thrombin times, and Factor Xa assays. These substrates were also tested for platelet adhesion and activation reactions in vitro using polymer-coated beads in rabbit platelet-rich plasma. Heparinized polymers promoted low levels of platelet adhesion and serotonin release. Surface concentrations of heparin from bioactivity assays were then correlated with platelet adhesion and the extent of platelet release to assess the efficacy of this heparin-immobilized copolymer as a blood-compatible material or coating

Adriamycin-loaded albumin-heparin conjugate microspheres for intraperitoneal chemotherapy

Adriamycin-loaded albumin-heparin conjugate microspheres (ADR-AHCMS) were evaluated as possible intraperitoneal (i.p.) delivery systems for site-specific cytotoxic action. The biocompatibility of the microspheres after intraperitoneal injection was tested first. 1 day after i.p. administration of empty as well as drug-loaded AHCMS to male Balb/c mice, only a moderate increase in i.p. neutrophils was measured. 3 days after injection neutrophil levels were comparable with the controls. No significant increases in the numbers of other cell types were observed, indicating an acute inflammatory response which can be considered to be mild. Antitumour efficacy was tested in an L1210 tumour-bearing mouse model and in a CC531 tumour-bearing rat model. The use of ADR-AHCMS leads to longer survival times of mice and improved tumour growth delay in rats, as compared with untreated controls and free drug treated animals. In both animal models higher adriamycin doses were initially tolerated if the drug was formulated in microspheres, although long-term adriamycin toxicity effects were evident in all treated groups. Doses and dosage schedules may be optimized to further reduce the toxic effects of the drug

Micro-computed tomographic assessment following extremely oversized partial postdilatation of drug-eluting stents

AIMS: To assess the spatial geometry of drug-eluting stents (DES) following extremely oversized proximal postdilatation. Interventions of distal left main (LM) disease generally require stenting across the LM bifurcation with inherent vessel tapering along this segment and a high likelihood of stent malapposition, which can be avoided by such postdilations. METHODS AND RESULTS: Sixteen DES (four 3.5 mm-samples of Cypher Select Plus, Taxus Liberté, Endeavor Resolute, Xience V) were deployed in water; 12 samples were then proximally postdilated with noncompliant 5.0 mm balloons at 18 atm. All samples were examined by micro-computed tomography. Taxus Liberté, Endeavor Resolute, and Xience V, showed increased cell areas in the transitional region (just distal to postdilated region), while Cypher Select showed its largest cells inside the postdilated region. Overall, the largest maximum cell area was observed in Endeavor Resolute, while Cypher Select showed the smallest (p<0.001, for both). In addition, the size of the very proximal postdilated cells was relatively small in most DES except Xience V. CONCLUSIONS: Extremely oversized partial stent postdilatation demonstrated significant between-DES differences in final spatial stent configuration and maximum cell size. These data could be of practical interest with regard to coronary interventions in LM stems with stenting across the LM bifurcation

Arc-minute-scale studies of the interstellar gas towards HESS \,J1804−-216: Still an unidentified TeV γ\gamma-ray source

The Galactic TeV $\gamma$-ray source HESS$\,$J1804$-$216 is currently an unidentified source. In an attempt to unveil its origin, we present here the most detailed study of interstellar gas using data from the Mopra Southern Galactic Plane CO Survey, 7 and 12$\,$mm wavelength Mopra surveys and Southern Galactic Plane Survey of HI. Several components of atomic and molecular gas are found to overlap HESS$\,$J1804$-$216 at various velocities along the line of sight. The CS(1-0) emission clumps confirm the presence of dense gas. Both correlation and anti-correlation between the gas and TeV $\gamma$-ray emission have been identified in various gas tracers, enabling several origin scenarios for the TeV $\gamma$-ray emission from HESS$\,$J1804$-$216. For a hadronic scenario, SNR$\,$G8.7$-$0.1 and the progenitor SNR of PSR$\,$J1803$-$2137 require cosmic ray (CR) enhancement factors of $\mathord{\sim} 50$ times the solar neighbour CR flux value to produce the TeV $\gamma$-ray emission. Assuming an isotropic diffusion model, CRs from both these SNRs require a slow diffusion coefficient, as found for other TeV SNRs associated with adjacent ISM gas. The morphology of gas located at 3.8$\,$kpc (the dispersion measure distance to PSR$\,$J1803$-$2137) tends to anti-correlate with features of the TeV emission from HESS$\,$J1804$-$216, making the leptonic scenario possible. Both pure hadronic and pure leptonic scenarios thus remain plausible.Comment: 29 pages, 23 figures, 5 tables, accepted for publication in PAS

Socioeconomic inequalities in pregnancy outcome associated with Down syndrome: a population-based study.

OBJECTIVE: To investigate socioeconomic inequalities in outcome of pregnancy associated with Down syndrome (DS) compared with other congenital anomalies screened for during pregnancy. DESIGN AND SETTING: Retrospective population-based registry study (East Midlands & South Yorkshire in England). PARTICIPANTS: All registered cases of DS and nine selected congenital anomalies with poor prognostic outcome (the UK Fetal Anomaly Screening Programme (FASP)9) with an end of pregnancy date between 1 January 1998 and 31 December 2007. MAIN OUTCOME MEASURES: Poisson regression models were used to explore outcome measures, including socioeconomic variation in rates of anomaly; antenatal detection; pregnancy outcome; live birth incidence and neonatal mortality. Deprivation was measured using the Index of Multiple Deprivation 2004 at super output area level. RESULTS: There were 1151 cases of DS and 1572 cases of the nine severe anomalies combined. The overall rate of antenatal detection was 57% for DS, which decreased with increasing deprivation (rate ratio comparing the most deprived tenth with the least deprived: 0.76 (0.60 to 0.97)). Antenatal detection rates were considerably higher for FASP9 anomalies (86%), with no evidence of a trend with deprivation (0.99 95% CI (0.84 to 1.17)). The termination of pregnancy rate following antenatal diagnosis was higher for DS (86%) than the FASP9 anomalies (70%). Both groups showed wide socioeconomic variation in the termination of pregnancy rate (rate ratio: DS: 0.76 (0.58 to 0.99); FASP9 anomalies: 0.80 (0.65 to 0.97)). Consequently, socioeconomic inequalities in live birth and neonatal mortality rates associated with these anomalies arise that were not observed in utero. CONCLUSIONS: Socioeconomic inequalities exist in the antenatal detection of DS, and subsequent termination rates are much higher for DS than other anomalies. Termination rates for all anomalies are lower in more deprived areas leading to wide socioeconomic inequalities in live born infants with a congenital anomaly, particularly DS, and subsequent neonatal mortality

Dispatch from the field: ecology of ground-web-building spiders with description of a new species (Araneae, Symphytognathidae).

Crassignathadanaugirangensis sp. n. (Araneae: Symphytognathidae) was discovered during a tropical ecology field course held at the Danau Girang Field Centre in Sabah, Malaysia. A taxonomic description and accompanying ecological study were completed as course activities. To assess the ecology of this species, which belongs to the ground-web-building spider community, three habitat types were surveyed: riparian forest, recently inundated riverine forest, and oil palm plantation. Crassignathadanaugirangensis sp. n. is the most abundant ground-web-building spider species in riparian forest; it is rare or absent from the recently inundated forest and was not found in a nearby oil palm plantation. The availability of this taxonomic description may help facilitate the accumulation of data about this species and the role of inundated riverine forest in shaping invertebrate communities