Selenium Nanowire Formation by Reacting Selenate with Magnetite.

The mobility of 79Se, a fission product of 235U and long-lived radioisotope, is an important parameter in the safety assessment of radioactive nuclear waste disposal systems. Nonradioactive selenium is also an important contaminant of drainage waters from black shale mountains and coal mines. Highly mobile and soluble in its high oxidation states, selenate (Se(VI)O42-) and selenite (Se(IV)O32-) oxyanions can interact with magnetite, a mineral present in anoxic natural environments and in steel corrosion products, thereby being reduced and consequently immobilized by forming low-solubility solids. Here, we investigated the sorption and reduction capacity of synthetic nanomagnetite toward Se(VI) at neutral and acidic pH, under reducing, oxygen-free conditions. The additional presence of Fe(II)aq, released during magnetite dissolution at pH 5, has an effect on the reduction kinetics. X-ray absorption spectroscopy analyses revealed that, at pH 5, trigonal gray Se(0) formed and that sorbed Se(IV) complexes remained on the nanoparticle surface during longer reaction times. The Se(0) nanowires grew during the reaction, which points to a complex transport mechanism of reduced species or to active reduction sites at the tip of the Se(0) nanowires. The concomitant uptake of aqueous Fe(II) and Se(VI) ions is interpreted as a consequence of small pH oscillations that result from the Se(VI) reduction, leading to a re-adsorption of aqueous Fe(II) onto the magnetite, renewing its reducing capacity. This effect is not observed at pH 7, where we observed only the formation of Se(0) with slow kinetics due to the formation of an oxidized maghemite layer. This indicates that the presence of aqueous Fe(II) may be an important factor to be considered when examining the environmental reactivity of magnetite.

Fate of Ag-NPs in Sewage Sludge after Application on Agricultural Soils.

The objective of this work was to investigate the fate of silver nanoparticles (Ag-NPs) in a sludge-amended soil cultivated with monocot (Wheat) and dicot (Rape) crop species. A pot experiment was performed with sludges produced in a pilot wastewater treatment plant containing realistic Ag concentrations (18 and 400 mg kg(-1), 14 mg kg(-1) for the control). Investigations focused on the highest dose treatment. X-ray absorption spectroscopy (XAS) showed that Ag2S was the main species in the sludge and amended soil before and after plant culture. The second most abundant species was an organic and/or amorphous Ag-S phase whose proportion slightly varied (from 24% to 36%) depending on the conditions. Micro and nano X-ray fluorescence (XRF) showed that Ag was preferentially associated with S-rich particles, including organic fragments, of the sludge and amended soils. Ag was distributed as heteroaggregates with soil components (size ranging from ≤0.5 to 1-3 µm) and as diffused zones likely corresponding to sorbed/complexed Ag species. Nano-XRF evidenced the presence of mixed metallic sulfides. Ag was weakly exchangeable and labile. However, micronutrient mobilization by plant roots and organic matter turnover may induce Ag species interconversion eventually leading to Ag release on longer time scales. Together, these data provide valuable information for risk assessment of sewage sludge application on agricultural soils.

Formation of Mercury Sulfide from Hg(II)-Thiolate Complexes in Natural Organic Matter.

Methylmercury is the environmental form of neurotoxic mercury that is biomagnified in the food chain. Methylation rates are reduced when the metal is sequestered in crystalline mercury sulfides or bound to thiol groups in macromolecular natural organic matter. Mercury sulfide minerals are known to nucleate in anoxic zones, by reaction of the thiol-bound mercury with biogenic sulfide, but not in oxic environments. We present experimental evidence that mercury sulfide forms from thiol-bound mercury alone in aqueous dark systems in contact with air. The maximum amount of nanoparticulate mercury sulfide relative to thiol-bound mercury obtained by reacting dissolved mercury and soil organic matter matches that detected in the organic horizon of a contaminated soil situated downstream from Oak Ridge, TN, in the United States. The nearly identical ratios of the two forms of mercury in field and experimental systems suggest a common reaction mechanism for nucleating the mineral. We identified a chemical reaction mechanism that is thermodynamically favorable in which thiol-bound mercury polymerizes to mercury-sulfur clusters. The clusters form by elimination of sulfur from the thiol complexes via breaking of mercury-sulfur bonds as in an alkylation reaction. Addition of sulfide is not required. This nucleation mechanism provides one explanation for how mercury may be immobilized, and eventually sequestered, in oxygenated surface environments.

Combined radiotherapy, 5-fluorouracil continuous infusion and weekly oxaliplatin in advanced rectal cancer: a phase I study.

The aim of this study was to determine the maximum-tolerated dose (MTD) of weekly oxaliplatin combined with 5-fluorouracil (5FU) continuous infusion administered concomitantly with fractionated radiotherapy in patients presenting advanced rectal cancer. Forty-three patients with rectal cancer (stage T3/T4 (n = 24), metastatic (n = 17) and 2 with local recurrence), were included. The radiotherapy dose delivered was 45 Gy over 5 weeks (1.8 Gy/fraction/day, 5 days per week). The initial weekly oxaliplatin dosage was 30 mg/m2 and the 5FU dosage 150 mg/m2/d. The oxaliplatin and 5FU doses were escalated. Eight dose levels were tested. At dose level 8 (oxaliplatin 80 mg/m2, 5FU 225 mg/m2/d), 2 patients out of 4 presented dose-limiting toxicity (severe diarrhoea with dehydration and fatal shock, rectovesical fistula). At dose level 7, 2 further patients presented with grade 3 diarrhoea. The main toxicity of the combination was diarrhoea. The hematological and neurological toxicities were not severe and were not dose-limiting. Out of the 30 patients undergoing surgery, 4 (13.3%) presented with pathological complete response and 4 (13.3%) only presented with microscopic residual disease. The results from this study enabled determination of the recommended weekly oxaliplatin dose (60 mg/m2) combined with 5FU continuous infusion (225 mg/m2) and fractionated radiotherapy (45 Gy) in the pre-operative treatment of advanced rectal cancer. The good safety profile of the regimen, associated with promising results in terms of histological response, suggest that the regimen could be developed in future phase II/III studies.

Neoadjuvant preoperative chemoradiation in patients with pancreatic cancer.

PURPOSE: To assess the toxicity and efficacy of preoperative chemoradiation in pancreatic cancer. METHODS AND MATERIALS: Between November 1996 and December 2001, 32 patients with biopsy-proven pancreatic adenocarcinoma (28 head; 4 body) were treated by chemoradiation consisting of either split-course therapy (two courses of 15 Gy separated by a 2-week break, n = 10) or standard-fractionation therapy (45 Gy during 5 weeks, n = 22). Concurrent chemotherapy included continuous infusion of 5-fluorouracil and a cisplatin bolus. Pancreatic resection was scheduled for 4-6 weeks after completion of chemoradiation treatment. RESULTS: All 32 patients completed the chemoradiation protocol. Only 2 cases of Grade 3 toxicity (weight loss, vomiting) and one fatal Grade 4 infection occurred. Of the 32 patients, 19 underwent curative resection. Two patients had a complete pathologic response. One patient died 36 months after diagnosis of late treatment-related toxicity (acute superior mesenteric artery thrombosis) with no evidence of disease. The 2-year overall survival rate for the entire group and the resected patients was 37.3% (95% confidence interval 18.2-56.4%) and 59.3% (95% confidence interval 34.1-84.9%), respectively. CONCLUSION: Preoperative chemoradiation with 5-fluorouracil and cisplatin is feasible and promising.

Assessment of pathologic response after preoperative chemoradiotherapy and surgery in pancreatic adenocarcinoma.

PURPOSE: The benefits provided by preoperative chemoradiotherapy (CRT) in pancreatic ductular adenocarcinoma (PDA) are still controversial. However, in most reports from referral centers, improvement in local control and survival appears to be provided in selected patients. The aim of this retrospective study was to analyze the radiation-induced pathologic effects of preoperative CRT in patients with resectable PDA and determine the precise long-term outcome of the responding patients. METHODS AND MATERIALS: Between November 1996 and October 2003, 61 patients underwent preoperative CRT for resectable PDA. The tumor location was the pancreatic head in 49 patients and pancreatic body in 12 patients. Of the 61 patients, 21 (34.5%) did not undergo surgery because of disease progression and 40 (65.5%) underwent pancreatic resection, including pancreaticoduodenectomy in 32 (80%) and distal pancreatectomy in 8 (20%). RESULTS: A major pathologic response was noted in 9 patients, including three complete responses, and was found only in patients with tumor of the pancreatic head. The local control rate was similar in patients with and without a major pathologic response. Survival in patients with a major response was significantly greater than in those without a response or with a minor response. CONCLUSION: Major tumor downstaging can be provided by preoperative CRT in patients with resectable cephalic PDA. Survival appears to be significantly improved in selected patients.

Locally advanced adenocarcinomas of the gastric cardia: results of pre-operative chemoradiotherapy.

UNLABELLED: Overall prognosis of adenocarcinomas of the gastro-esophageal junction remains poor as most patients present with advanced disease. AIM: To examine the effects of preoperative chemoradiotherapy in locally advanced adenocarcinomas of the gastro-esophageal junction. METHODS: Forty-two consecutive patients received a course of radiotherapy (45 Gy, administred in 25 fractions) with concurrent infusion of 5-Fluorouracil and cisplatin, followed by surgery. Endoscopic ultrasonography was used to assess response to chemoradiotherapy. A transhiatal or a transthoracic approach was used for surgical resection. Tumor size, node invasion and margins of resection were analyzed. RESULTS: Thirty-eight patients underwent subsequent surgery and complete resection (RO) was achieved in 34. Operative mortality was 13.2% (5/38). A histological complete response was observed in 6 patients. Median survival was 23 months (range: 15-31) and median disease-free survival was 19 months (range: 15-23). At one and two years, 70.7 and 45.6% of the patients were alive, respectively. The pTNM status, node involvement and tumor size were predictors of survival. CONCLUSIONS: Pre-operative chemoradiotherapy is effective in patients with locally advanced carcinoma of the gastro-esophageal junction, resulting in high resection rates. However it seems to increase operative morbidity and mortality. Certain prognostic factors such as resection margins, need to be examined in further detail.

Radiotherapy for a phalanx bone metastasis of a lung adenocarcinoma.

Phalanx bone metastasis as the initial presenting sign of lung cancer is a rare presentation. Lung cancer is known to metastasize to the bone, but rarely to the fingers. A 61-year-old male smoker presented with pain in the left ring finger. Severe pain discouraged the patient from using his left hand. An X-ray of the left hand showed a lytic bone lesion. The patient was treated with finger radiotherapy. Analgesics were no longer needed and the patient was able to reuse his left hand in his everyday life. Palliative radiotherapy relieved our patient and improved his quality of life.

Foliar or root exposures to smelter particles: consequences for lead compartmentalization and speciation in plant leaves.

In urban areas with high fallout of airborne particles, metal uptake by plants mainly occurs by foliar pathways and can strongly impact crop quality. However, there is a lack of knowledge on metal localization and speciation in plants after pollution exposure, especially in the case of foliar uptake. In this study, two contrasting crops, lettuce (Lactuca sativa L.) and rye-grass (Lolium perenne L.), were exposed to Pb-rich particles emitted by a Pb-recycling factory via either atmospheric or soil application. Pb accumulation in plant leaves was observed for both ways of exposure. The mechanisms involved in Pb uptake were investigated using a combination of microscopic and spectroscopic techniques (electron microscopy, laser ablation, Raman microspectroscopy, and X-ray absorption spectroscopy). The results show that Pb localization and speciation are strongly influenced by the type of exposure (root or shoot pathway) and the plant species. Foliar exposure is the main pathway of uptake, involving the highest concentrations in plant tissues. Under atmospheric fallouts, Pb-rich particles were strongly adsorbed on the leaf surface of both plant species. In lettuce, stomata contained Pb-rich particles in their apertures, with some deformations of guard cells. In addition to PbO and PbSO4, chemical forms that were also observed in pristine particles, new species were identified: organic compounds (minimum 20%) and hexagonal platy crystals of PbCO3. In rye-grass, the changes in Pb speciation were even more egregious: Pb-cell wall and Pb-organic acid complexes were the major species observed. For root exposure, identified here as a minor pathway of Pb transfer compared to foliar uptake, another secondary species, pyromorphite, was identified in rye-grass leaves. Finally, combining bulk and spatially resolved spectroscopic techniques permitted both the overall speciation and the minor but possibly highly reactive lead species to be determined in order to better assess the health risks involved.

Short-term outcome after laparoscopic or open restorative mesorectal excision for rectal cancer: a comparative cohort study.

PURPOSE: The laparoscopic approach to rectal cancer is still a controversial procedure. A comparative cohort study was conducted to assess short-term results of laparoscopic restorative mesorectal excision. METHODS: From January 1998 to December 2000, laparotomy was performed on all primary rectal cancer undergoing radical excision. From January 2002 to September 2004, all cases about to undergo radical excision were considered for laparoscopy. Patients with fixed tumor or T4, indications for synchronous hepatectomy, emergencies, and medical contraindications were not included. The study was based on the intention-to-treat principle. RESULTS: Short-term outcome was compared between the laparoscopy group (n=104) and the laparotomy group (n=68). Demographic, general and tumor data, and rates of preoperative irradiation were comparable, as were surgical procedures and perioperative management. Hospital mortality (1 and 2.9 percent, P=0.33) and three-month overall morbidity (43.3 and 48.5 percent, P=0.49) were comparable between laparoscopy and laparotomy groups. Surgical complication rates were comparable (39.3 and 35.5 percent, P=0.58), but a significantly lower medical complication rate was observed in laparoscopy patients (8.7 and 20.6 percent, P=0.025), mainly because this group had fewer respiratory complications. Hospital stay was shorter in laparoscopy patients (10 and 14 days, P<0.001). Oncologic quality criteria were comparable, in terms of number of lymph nodes, lateral and distal margins, and delivery of postoperative chemotherapy. CONCLUSIONS: The laparoscopic approach to restorative mesorectal excision for cancer does not increase postoperative morbidity or reduce oncologic quality. Our results suggest that the short-term outcome is probably improved with this procedure.

Salvage abdominoperineal resection after failure of conservative treatment in anal epidermoid cancer.

PURPOSE: Radiotherapy alone or with combined chemotherapy is the first therapeutic option for epidermoid carcinoma of the anal canal. Failure of this conservative treatment may benefit of salvage abdominoperineal resection. This study was designed to analyze postoperative outcome and oncologic results in a single anticancer institution. METHODS: Medical charts of 36 patients (median age, 57.9 years) who underwent salvage abdominoperineal resection after failure of conservative treatment between 1987 and 2002 were reviewed retrospectively. There were 15 patients treated for immediate failure (Group I) and 21 patients for recurrence (Group II). Twenty-two patients have undergone primary use of flap reconstruction of the perineal wound. There were ten rectus abdominis myocutaneous flaps, nine omental flaps, two gracilis muscular flaps, and one combined flap. RESULTS: There was no postoperative mortality. Median follow-up was 67 (range, 15-155) months. Primary closure of the perineum was obtained in 33 patients (92 percent). Secondary wound breakdown occurred in 23 of 33 patients (70 percent). Complications unrelated to the perineal wound occurred in 13 patients. The overall crude five-year survival after salvage abdominoperineal resection was 69.4 percent. The crude five-year survival in Group I and Group II was 60.7 and 71.5 percent respectively (P = 0.28). The crude five-year, disease-free survival in Groups I and II was 31.1 and 48.2 percent respectively (P = 0.10). Twenty-three patients experienced recurrences after salvage abdominoperineal resection (64 percent) with a mean delay of 30 months. CONCLUSIONS: Despite high incidence of perineal morbidity, salvage abdominoperineal resection for epidermoid carcinomas of the anal canal has a high long-term survival rate.

Hemorrhage after duodenopancreatectomy: impact of neoadjuvant radiochemotherapy and experience with sentinel bleeding.

Postoperative hemorrhage (PH) after duodenopancreatectomy (DP) is frequently lethal. The aim of this study was to delineate guidelines of management. Between August 1994 and July 2003, 172 patients underwent DP for cancer. Altogether, 26 patients were subjected to an institutional protocol (IP) with standard-dose chemoradiation (CRT) and 4 patients to an extrainstitutional protocol (EIP) with high-dose CRT. Sixteen patients (9.3%) were reoperated for PH. Hemorrhage occurred in 23% of irradiated patients (4 EIP, 3 IP) and in 6% of nonirradiated patients [confidence interval (CI) 1.8-6.5]. Pancreatic leak occurred in nine patients with PH (56%). Sentinel bleeding (SB) was noted in eight patients (50%) with a mean delay of 10 days after DP. Overall mortality after hemorrhage was 56%. Morality rates of patients with EIP or IP were, respectively, 100% and 0%. Mortality rates of patients with or without SB were similar. Mortality rates of axial bleeding (hepatic artery, mesenteric vessels) or lateral bleeding (pancreas remnant, splenic vessels) were, respectively, 88% and 25% (CI 1.6-8.6). Completion of pancreatectomy was achieved in 75% without rebleeding. Preoperative high-dose CRT increased the risk of fatal PH. Because SB occurs before massive hemorrhage, prompt reoperation could reduce mortality. Completion of pancreatectomy was essential during reintervention. Axial bleeding supports high mortality. Moving to the left, the pancreatojejunostomy could avoid contact of pancreatic juice with axial vessels in the case of pancreatic leakage. Ligating the gastroduodenal artery during DP had to leave a stump of around 1 cm to facilitate hemorrhage control without ligating the common hepatic artery.