Degradation studies of new substitutes for perfluorinated surfactants.

Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) are manmade, stable perfluorosurfactants. The properties of perfluoroalkylated compounds that cause them to persist in the environment are also the properties that made them attractive compounds for industrial usage for over 50 years. Due to the unique properties of the carbon-fluorine bond and the polarity of perfluoroalkyl groups, potential substitutes to replace perfluorinated surfactants in most cases continue to be perfluoroalkyl based. Thus, issues of persistence in the environment remain. There is a need to test emerging new substitute surfactants for biodegradability. This study involved degradability measurements of emerging perfluorinated surfactant substitutes. The stability of the substitutes of perfluorinated surfactants was tested by employing advanced oxidation processes, which were based on degradation by ultraviolet lamp, hydrogen peroxide, or both, followed by conventional tests, among them an automated method based on the manometric respirometry test (OECD 301 F; OxiTop), closed-bottle test (OECD 301 D), and standardized fixed-bed bioreactor on perfluorobutane sulfonate, fluorosurfactant Zonyl, two fluoraliphatic esters (NOVEC FC-4430 and NOVEC FC-4432), and 10-(trifluoromethoxy) decane 1 sulfonate. Most of these new surfactants are well established in the marketplace and have been used in several applications as alternatives to PFOS- and PFOA-based surfactants. Ready biodegradation tests for fluoroaliphatic esters, the fluorosurfactant Zonyl, perfluorobutane sulfonate, and 10-(trifluoromethoxy) decane-1-sulfonate using the manometric respirometry test (OxiTop) did not meet the ready biodegradability test criteria. However, 10-(trifluoromethoxy) decane-1-sulfonate was observed to be degradable when a standardized fixed-bed bioreactor test was applied.

omega-(Bis(trifluoromethyl)amino)alkane-1-sulfonates: synthesis and mass spectrometric study of the biotransformation products.

In search of fluorinated functional groups which could undergo defluorination, and therefore be included in novel non-polluting fluorinated surfactants, omega-(bis(trifluoromethyl)amino)alkane-1-sulfonates (BTFMA-AS) with a homologue distribution from seven to thirteen methylene groups were synthesized and investigated for aerobic biodegradation applying both a standardized test and a fixed-bed bioreactor (FBBR). These compounds were prepared as part of a screening study for potentially mineralizable fluorinated endgroups.Application of hybrid triple quadrupole-linear ion trap mass spectrometry (QqQ(LIT)-MS) coupled to high-performance liquid chromatography (HPLC) allowed the tracking of primary degradation as well as the detection and structural elucidation of biotransformation intermediates. An understanding of the fragmentation pathway of the test compounds allowed selective precursor ion scans to reveal the presence of stable fluorinated metabolites. Structures were confirmed by enhanced product ion scans and MS(3) scans in the linear ion trap mode.The primary biodegradation rate and the extent of biodegradation were found to be chain-length dependent, with higher homologues being completely primarily degraded within 10 days. For the first time, two simultaneous metabolic pathways for substituted linear alkane-1-sulfonates were discovered: Desulfonation, oxidation to a carboxylic acid and subsequent chain-length shortening by beta-oxidation dominated the metabolism. This pathway resulted in the formation of 3-(bis(trifluoromethyl)amino)propionic acid and bis(trifluoromethyl)aminoacetic acid, which showed recalcitrance in this experiment. Oxidation of the alkyl chain to the respective carbonyl derivative represents the minor pathway. Only the long-chain homologues of these oxidized species were partially degraded; the short-chain homologues were not attacked.

Do various mesh placement techniques affect the outcome in totally extraperitoneal hernia repair? What is the role of the surgeon?

BACKGROUND: Various modifications of mesh placement are currently used in total extraperitoneal (TEP) groin hernia repair. The aim of this study was to compare three different variants of mesh placement with respect to rate of complications and clinical outcome. METHODS: A series of 397 consecutive patients with a total of 534 preperitoneal groin hernia TEP repairs performed by four surgeons at a single institution between 1999 and 2003 were retrospectively analyzed. The mean follow-up was 19.7 +/- 7.5 months. A single-mesh technique was used in cases of hernial orifice <1.5 cm. Larger hernial defects were closed either in a double-mesh or a modified double-mesh placement technique. The three placement techniques were compared with respect to hospital stay, operative time, early and late complications, return-to-work time, and recurrence rate. RESULTS: The modified double-mesh technique was associated with the longest hospital stay, the longest operative time, the slowest return to work, and significantly higher rates of early (5.6% vs. 4.6% vs. 2.9%) and late (19.1% vs. 11.3% vs. 7.9%) postoperative complications, when compared to double-and single-mesh placement. Overall recurrence rate was 1.3% after a mean follow-up of 19.7 months. The larger the experience of a surgeon with his preferred technique, the shorter the operative time and hospital stay were. CONCLUSIONS: Mesh placement techniques appeared to have a direct impact on clinical outcome and hospital stay. The modified double-mesh technique showed the worst postoperative results, independent of the surgeon's experience. Which mesh placement technique is most appropriate for complex hernias remains to be answered by further randomized, controlled trials.

A case of port-site recurrence after laparoscopic adrenalectomy for solitary adrenal metastasis.

The case of a patient with bilateral adrenal metastases from lung cancer is described. A left open adrenalectomy at the time of the lung resection had a long-term curative effect. Several months later a right laparoscopic adrenalectomy was performed, but 2 months later a loco-regional recurrence with a port-site metastasis was diagnosed on the right side. Open adrenalectomy, by avoiding the potential for port-site metastasis, may be oncologically superior to laparoscopic adrenalectomy in this situation.

Improving outcomes in hernia repair by the use of light meshes--a comparison of different implant constructions based on a critical appraisal of the literature.

BACKGROUND: Despite convincing advantages offered by meshes, their use in hernia surgery remains controversial because of fears concerning the long-term effects of their implantation. To improve biocompatibility, a large variety of newly developed light meshes has been introduced to the market. This overview of the literature aimed to establish whether absolute material reduction (g per implanted mesh), use of absorbable components, and coating by inert materials are evidence-based ways to improve biocompatibility of meshes. METHOD: A review of the current English and German language literature on the outcome of groin und incisional hernia mesh repair was performed. Both basic research and clinical trials were used as sources of data. Meta-analyses and randomized controlled trials were given priority and were referred to whenever possible. RESULTS: Operative technique was an independent prognostic factor for the clinical outcome. Mesh construction and composition as characterized by pore size and filament structure appeared to be more important determinants of foreign body reaction after implantation than absolute material reduction of 1 g or more per implant. No data exist about an oncogenic effect of alloplastic materials in humans, but disturbed fertility in animal studies remains an issue of concern and should be further investigated. CONCLUSIONS: According to data from current randomized controlled trials and retrospective studies, light meshes seem to have some advantages with respect to postoperative pain and foreign body sensation. However, their use is associated with increased recurrence rates. Light meshes offer no advantages with respect to alleviating severe chronic groin pain. At the same time, experimental data reveal that material composition and mesh structure may significantly affect foreign body reaction.