Determination of multi-class polyaromatic compounds in sediments by a simple modified matrix solid phase dispersive extraction

A simple, efficient matrix solid phase dispersive extraction (MSPD) method was optimised to analyse simultaneously polycyclic aromatic hydrocarbons (PAHs) and polychlorobiphenyls (PCBs) from sediments, and was compared to microwave-assisted extraction (MAE). New dispersing agents were tested to improve MSPD extraction. 3-chloropropyl-bonded silica particles, in addition to Florisil, increased significantly the polyaromatics desorption capacity. A compromise was found for eluting both families of compounds from sediments, using a small volume of hexane/acetone. Low procedural detection limits could be reached (0.06-0.22 ng g^-1 and 0.3-1.1 ng g^-1 for PAHs and PCBs, respectively). Mean total extraction recoveries were good for PAHs (>67%, depending on the sediment) and for PCBs (>89%), with good precision (6-9% and 4-10% inter-day precision for PAHs and PCBs, respectively). Higher recoveries for PCBs could be reached in comparison with formerly developed sonication or Soxhlet extraction methods, but also with MAE. MSPD offered significant decrease of sample amount, of solvent consumption and allowed more efficient cleaning of the sediment matrix, leading to less matrix effects compared to MAE, removing lots of interfering compounds without additional purification step. The robustness of the MSPD methodology could be demonstrated extracting quantitatively sediments from different sources and with various mineralogical characteristics.

Enhanced electrokinetic remediation of multi-contaminated dredged sediments and induced effect on their toxicity

Electrokinetic (EK) remediation is often developed for metal decontamination but shows limitations for polycyclic aromatic hydrocarbons (PAHs) and polychlorobiphenyls (PCBs) which are nonionic and involve low aqueous solubility. This paper reports many laboratory studies devoted to the investigations of EK efficiency on the mobility and the removal of metals, PAHs and PCBs from dredged sediments, using a mixture of chelating agent and surfactants. The results showed that increasing chelating agent concentration was favorable for both metal and PAH removal. Applying a periodic voltage gradient associated to a low concentration of additives provided the best removal of Zn, Cd and Pb and also the 16 priority PAHs. The tested fresh harbor sediment was highly resistant to metals and organics mobilization and transport because of an aged contamination, a high buffering capacity, a very low hydraulic permeability and a high organic matter content. However, experiments performed on a former sediment which was deposited many years ago provided better removal results, involving low organic matter and carbonates content. The efficiency of the EK process was also assessed by measuring the acute toxicity of the EK-treated sediment on the copepod Eurytemora affinis exposed to sediment elutriates.

Application of a crustacean bioassay to evaluate a multi-contaminated (metal, PAH, PCB) harbor sediment before and after electrokinetic remediation using eco-friendly enhancing agents

Electrokinetic (EK) remediation can be a suitable technology for treating contaminated dredged harbor sediment, stored on terrestrial disposal sites. Citric acid (CA) and biosurfactants (rhamnolipids and saponin) were chosen as enhancing agents for simultaneous metal (Cd, Cr, Cu, Pb, Zn) and PAH/PCB removal by EK because of their potential low toxicity with a view to site restoration. Three EK runs were performed using a periodic voltage (1Vcm^-1) and various concentrations of agents. The best combination of CA (0.2molL^-1) and saponin (0.85gL^-1) did not remove high amounts of metals (4.4-15.8%) and provided only slightly better results for PAH and PCB removal (29.2% and 38.2%, respectively). The harbor sediment was highly resistant to metal and organics mobilization and transport because of an aged contamination, a high buffering capacity, a very low hydraulic permeability and a high organic matter content. The efficiency of the EK process was also assessed by measuring the acute toxicity of the EK-treated sediment on E. affinis copepods exposed to sediment elutriates. Fortunately, the use of CA and biosurfactants did not significantly impact on sediment toxicity. Some treated sediment sections, particularly those near the anode compartment, were statistically more toxic than the raw sediment. More particularly, E. affinis copepods were significantly sensitive to low pH values and oxidative conditions, to Cu, and to a lesser extent to Pb amounts. The speciation of these metals probably changed in these pH and redox conditions so that they became more easily leachable and bioavailable. In contrast, toxicity was negatively correlated to PAH and PCB amounts after EK treatment, probably due to the production of oxidized metabolites of PAHs and PCBs.

Application of biosurfactants and periodic voltage gradient for enhanced electrokinetic remediation of metals and PAHs in dredged marine sediments

Dredged harbor sediment co-contaminated by heavy metals and polycyclic aromatic hydrocarbons (PAHs) was subjected to enhanced electrokinetic treatments, using a mixture of a chelating agent (citric acid CA) and a surfactant as additives in the processing fluids. We tested various operating conditions (at 1 V cm(-1)): different CA concentrations, applying a periodic voltage gradient, pre-conditioning the sediment with the additives, and replacing the synthetic surfactant Tween 20 (TW20) by biosurfactants. Increasing the CA concentration was favorable for both metal and PAH removal. Applying a periodic voltage gradient associated to a low concentration of CA and TW20 provided the best results for Zn, Cd and Pb removal and also for removal of the 16 priority PAHs. Promising results were obtained with solutions containing rhamnolipids (0.028%) and a viscosin-like biosurfactant produced by Pseudomonas fluorescens Pfa7B (0.025%), associated to a periodic voltage gradient. Although the rhamnolipid and the viscosin-like compounds involved a higher electrical current than TW20, metals were less removed from the sediment. The electroosmotic flow was lower when we used biosurfactants, hence a less effective effect on PAH removal.

Investigation of the release of PAHs from artificially contaminated sediments using cyclolipopeptidic biosurfactants

Polycyclic aromatic hydrocarbons (PAHs) can be preponderant in contaminated sediments and understanding how they are sorbed in the different mineral and organic fractions of the sediment is critical for effective removal strategies. For this purpose, a mixture of seven PAHs was studied at the sediment/water interface and sorption isotherms were obtained. The influence of various factors on the sorption behavior of PAHs was evaluated, such as the nature of minerals, pH, ionic strength and amount of organic matter. Afterwards, the release of PAHs from the sediment by surfactants was investigated. The effectiveness of sodium dodecyl sulfate (SDS) was compared to natural biosurfactants, of cyclolipopeptidic type (amphisin and viscosin-like mixture), produced by two Pseudomonas fluorescens strains. The desorption of PAHs (from naphthalene to pyrene), from the highly retentive kaolinite fraction, could be favored by adding SDS or amphisin, but viscosin-like biosurfactants were only effective for 2-3 ring PAHs desorption (naphthalene to phenanthrene). Moreover, while SDS favors the release of all the target PAHs from a model sediment containing organic matter, the two biosurfactants tested were only effective to desorb the lowest molecular weight PAHs (naphthalene to fluorene).

Ultrasonic measurements of particle retention by a porous medium

Ultrasound transmission and reflection are utilized to characterize the particle retention in depth of fluid-saturated porous samples under a flow of silt solution. The effect of the concentration of particles in the fluid is investigated via measurements of "comparison coefficients" which are the ratio of the Fourier transforms of the reflected (transmitted) signals before and after the particle flow. Numerical computations of the latter coefficients using Biot-Stoll's theory are compared to the experimental data. The frequential evolution of physical parameters such as bulk and shear moduli are sought. To this end, a gradient descent algorithm is utilized to minimize the differences between the experimental and calculated comparison coefficients. Several concentrations of suspended particles are investigated to check the validity of this inversion method and a good agreement between theory and experiments is observed.

[Hydatid cysts of the spleen: conservative or radical surgery? ]

Introduction

Concernant l’hydatidose, la localisation splénique vient en 3^ème position après le foie et les poumons. En l’absence de traitement médical réellement efficace, l’hydatidose splénique amène souvent à la chirurgie. L’apparition du traitement percutané et la tendance actuellement conservatrice de la chirurgie surtout pour une pathologie bénigne, remettent en cause la splénectomie radicale.

Méthode

Notre travail rétrospectif, a porté sur 23 cas d’hydatidose splénique isolés ou multi-viscérale. Le diagnostic reposait principalement sur le couple échographie abdominale et sérologie hydatique. Ces patients ont bénéficié dans leur majorité d’une splénectomie ou d’une résection du dôme saillant du kyste.

Résultats

La morbidité postopératoire a été plus importante en cas de résection du dôme saillant (une hémorragie d’origine splénique, 3 abcès sur cavité résiduelle et 2 récidives). La mortalité a été nulle. Nous proposons une classification qui permet de stratifier les indications opératoires en fonction du type de kyste hydatique de la rate.

Conclusion

Le choix entre chirurgie radicale ou conservatrice reste difficile vu les contraintes de chacune, les complications postopératoires respectives et la diversité des situations cliniques. Notre classification facilite ce choix.

Aortic valve replacement with the minimal extracorporeal circulation (Jostra MECC System) versus standard cardiopulmonary bypass: a randomized prospective trial

BACKGROUND

We prospectively evaluated a newly introduced minimal extracorporeal circulation system (Jostra MECC System; Jostra AG, Hirrlingen, Germany) for aortic valve surgery.

METHOD

In a prospective, randomized study, 100 patients underwent aortic valve replacement either with standard cardiopulmonary bypass (n = 50, group B) or with the MECC System (n = 50, group B). The myocardial protection and the left vent were identical for the two groups. The intrapericardial suction device was never used (only the cell salvage device was used) to reduce the air-blood contact area.

RESULTS

No significant differences were noted in patient characteristics and operative data between groups. Operative mortality (<30 days) was 2% for group A and 4% for group B (difference not significant). From the preoperative period to the postoperative period, the increase in C-reactive protein was significantly higher for group B (P <.001). The postoperative troponin I level was significantly lower in group A (mean 4.65 +/- 2.9 microg/L at 24 hours) than in group B (8.2 +/- 4.4 microg/L, P <.03). On the other hand, the MECC System was associated with platelet preservation. Renal function was better preserved and the neurologic event rate was significantly lower for the MECC group (P <.02).

CONCLUSION

The MECC System is safe and allows aortic valve replacement under the most favorable conditions. The system is more biocompatible than standard cardiopulmonary bypass and provides a good postoperative biologic profile and good clinical results, particularly for high-risk patients.

[Adenocarcinoma of the anal glands]

The study aim was to report an adenocarcinoma of the anal glands revealed by an anal abscess in a 64-year-old man. Malignant transformation of an anal fistula is discussed in the genesis of this disease. Clinical symptoms are not specific. Abdomino-perineal resection of the rectum is the usual surgical treatment and adjuvant radiation therapy didn't prove its efficiency.

[Inflammatory pseudotumor of the spleen]

Inflammatory pseudotumor of the spleen is a very rare benign lesion of unknown etiology. Splenectomy is recommended to obtain histological diagnosis and to eliminate a malignant tumor.

[Papillary fibroelastoma. Report of 3 cases]

Papillary fibroelastoma is a rare, benign, primary cardiac tumour. The authors report three cases presenting with transient or full cerebrovascular accidents. The tumours were diagnosed during investigation by echocardiography, especially transoesophageal echocardiography. In view of the severity of symptoms and the high risk of recurrence, the patients were rapidly referred for surgery. In two cases, the tumour was located on the aortic valve at several sites. In one case, the tumour was single and implanted on the mitral valve. Surgery was successful with the pathology reports confirming complete ablation. The patients have not had any recurrence to date. The multiple nature of these tumours raises the questions of local spread, secondary degeneration of valvular nodes? The problem of possible recurrences is discussed.

[Place of super-selective vagotomy in the treatment of perforated duodenal ulcer]

Thirty-two duodenal ulcer perforations were treated by suture and supraselective vagotomy. Perioperative mortality was nil. The recurrence rate was 6.2% against 17% after elective supraselective vagotomy performed by the same surgeons during the same period. Results of this technique for treatment of perforated duodenal ulcer are compared with those of 28 simple sutures and 32 truncal vagotomies.