Patterns of recurrence of obstructing colon cancers after surgery for cure: a population-based study.

AIM: Little is known about patterns of recurrence in obstructing colon cancer (OCC) at a population level. The aim of this study was to determine the risk of recurrence following potentially curative surgery in OCC compared with that in uncomplicated colon cancer (CC). METHOD: Data were obtained from the population-based digestive cancer registry of Burgundy (France). Local and distant failure rates were calculated using actuarial methods. A multivariate analysis was performed using a Cox model. RESULTS: Obstructing colon cancer represented 8.5% of all colon cancers resected with curative intent (n = 3375). The 5-year cumulative local recurrence rate was 14.2% for OCC and 7.6% for nonobstructing CC (P = 0.003). In the multivariate analysis, obstruction was an independent risk factor for local recurrence [hazard ratio 1.53 (1.01-2.34), P = 0.047]. The risk of local recurrence increased with advanced stage and age at diagnosis. The 5-year cumulative rate for distant metastases was also higher in OCC than in nonobstructing CC (36.1 vs 23.1%; P < 0.001). The relative risk of distant metastasis was borderline significant in the multivariate analysis [hazard ratio 1.25 (0.99-1.59), P = 0.057]. Stage at diagnosis, macroscopic type of growth, period of diagnosis and sex were also significant prognostic factors. Age and subsite were not significant in the multivariate analysis. CONCLUSION: It is possible to conduct special surveys in population-based registries to determine the recurrence rate of CC. Recurrence remains a substantial problem and is more frequent in OCC than in nonobstructing CC. Efforts must be made to diagnose CC earlier. Mass screening is a promising approach.

Controlling the plasmon resonance of single metal nanoparticles by near-field anisotropic nanoscale photopolymerization.

We propose a new approach for tuning the Surface Plasmon (SP) resonance wavelength using hybrid nanoparticles. Our approach is based on nanoscale photopolymerization around metal nanoparticles. The enhanced optical near-field of silver nanoparticles triggers local photopolymerization. As a result, atomic force microscopy reveals two nanoscale polymerized lobes around nanoparticles, with a controlled effective index distribution. A spectral breaking degeneracy of surface plasmon resonance of the nanoparticles has been demonstrated by polarized extinction spectroscopy.

Modelling of the near-field of metallic nanoparticle gratings: localized surface plasmon resonance and SERS applications.

We numerically study the influence of the shape of gold nanostructures on the spectral position of their localized surface plasmon resonance and on Surface Enhanced Raman Scattering efficiency. Calculations are performed using a Finite-Difference Time-Domain (FDTD) method, whose accuracy for dispersive media is enhanced through the use of a Drude-Lorentz model. The relevance of this method is then pointed out by comparing the calculations with experimental data for both the plasmon resonance and the Raman signal enhancement. The influence of a thin layer of water is also investigated.

STEM and EDXS characterisation of physico-chemical reactions at the periphery of sol-gel derived Zn-substituted hydroxyapatites during interactions with biological fluids.

With its good properties of biocompatibility and bioactivity hydroxyapatite (HA) is highly used as bone substitutes and as coatings on metallic prostheses. In order to improve the bioactive properties of HA, we have elaborated Zn2+ doped hydroxyapatite. Zn2+ ions substitute for Ca2+ cations in the HA structure and four Zn concentrations (Zn/Zn+Ca) were prepared at 0.5, 1, 2 and 5 at.%. To study physico-chemical reactions at the materials periphery, we immersed the bioceramics into biological fluids for intervals from 1 day to 20 days. The surface changes were studied at the nanometer scale by scanning transmission electron microscopy associated with energy dispersive X-ray spectroscopy. After 20 days of immersion, we observed the formation of a calcium-phosphate layer at the periphery of the HA doped with 5% zinc. This layer contains magnesium and its thickness was around 200 nm. Formation of this Ca-P-Mg layer represents the bioactive properties of 5% Zn-substituted hydroxyapatite. This biologically active layer improves the properties of HA and will permit a chemical bond between the ceramic and bone.

Development of automated headspace gas chromatography determination of dithiocarbamates in plant matrixes.

The determination of dithiocarbamates in plant matrixes is generally carried out by spectrophotometric (European Norm EN 12396-1, 1996) or gas chromatography headspace (European Norm EN 12396-2, 1999) methods. However, the former method presents a risk of carbon disulfide loss during hydrolysis and distillation and its sensitivity is low, whereas the latter method is time-consuming. In comparison to these European methods and in compliance with norm V03-110, we have developed an automated gas chromatography headspace method. This method offers a good level of accuracy and precision and is specific to the compound determined (CS(2)). The limit of detection is below 0.020 mg/kg and the limit of quantification is below 0.050 mg/kg. Moreover, the recovery rates are between 85 and 103% with RSD less than 20%. The automated headspace method has several advantages when compared to the spectrophotometric and manual headspace methods, including the reduction of reagents employed for extraction and a greater number of analyses achievable per day than the other methods (approximately 40 samples of food).