Early Marginal Ulcer After Roux-en-Y Gastric Bypass: MBSAQIP Database Analysis of Trends and Predictive Factors

PURPOSE

Marginal ulcer (MU) is a known complication after Roux-en-Y gastric bypass (RYGB) that carries significant morbidity. First, we aimed to determine the trends and the rates of readmission, reintervention, and reoperation of 30-day MU. Second, we aim to determine the predictive factors associated with this complication.

MATERIALS AND METHODS

Patients who had 30-day marginal ulcer (MU) after LRYGB were identified using the 2015-2021 MBSAQIP database. Those who had a 30-day complication other than MU were excluded. Bivariate and logistic regression analyses were performed.

RESULTS

Among 213,104 patients undergoing laparoscopic RYGB, 638 (0.3%) showed 30-day MU. This group of patients required endoscopic interventions, readmissions, and reoperations at rates of 88%, 72%, and 9%, respectively. Predictive factors for 30-day MU after RYGB were renal insufficiency, history of DVT, previous cardiac stent, African American race, chronic steroid use, COPD, therapeutic anticoagulation, anastomotic leak test, GERD, and operative time > 120 min. Additionally, patients who had 30-day MU showed significantly higher rates of overall complications such as pulmonary, cardiac and renal complications, unplanned ICU admission, blood transfusions, venous thromboembolism (VTE), and non-home discharge (p < 0.05). The MU group showed similar rates of 30-day mortality as those without this complication (0.2% vs 0.1%, p = 0.587).

CONCLUSIONS

The incidence of 30-day MU following RYGB was 0.3%. Patients with MU required endoscopic interventions, readmissions, and reoperations at rates of 88%, 72%, and 9%, respectively. Some preoperative and intraoperative factors contributed to an increased risk of 30-day MU.

Impact of Body Mass Index ≥35 kg/m2 on Minimally Invasive Adrenalectomy

Introduction: Obesity is associated with numerous chronic conditions and an increased risk for surgical complications. Laparoscopic and robotic adrenalectomy have proven effective in the resection of adrenal tumors. This study analyzes the outcomes of severely obese patients (body-mass index [BMI] ≥35 kg/m2) following minimally invasive adrenalectomy. Materials and Methods: A retrospective analysis of patients who underwent minimally invasive adrenalectomy at our institution between 2010 and 2023 was conducted. Two matching analyses were performed. The first analysis compared patients with BMI greater versus lower than 35 kg/m2. The second analysis compared outcomes between robotic and laparoscopic adrenalectomy in patients with a BMI ≥35 kg/m2. Results: A total of 278 patients were included in the study. The median tumor size was 29 mm. Adrenal tumors had similar laterality, and most were hormonally active (66.2%). The most common pathological diagnosis was pheochromocytoma (25.5%). No statistical difference was found in peri- and postoperative outcomes between patients with BMI ≥35 and <35 kg/m2 who underwent minimally invasive adrenalectomy. When the surgical approach was compared in severely obese patients, robotic adrenalectomy was associated with shorter hospital length of stay with similar operative time as the laparoscopic approach. Conclusions: Minimally invasive adrenalectomy is safe and feasible in patients with BMI ≥35 kg/m2. Robotic and laparoscopic approaches are both safe and efficient for the resection of adrenal tumors in severely obese patients.

One anastomosis gastric bypass as a primary bariatric surgery: MBSAQIP database analysis of short-term safety and outcomes

BACKGROUND

One anastomosis gastric bypass (OAGB) is described as a simpler, potentially safe, and effective bariatric-metabolic procedure that has been recently endorsed by the American Society of Metabolic and Bariatric Surgery.

OBJECTIVES

First, we aim to compare the 30-day outcomes between OAGB and other bypass procedures: Roux-en-Y gastric bypass (RYGB) and single anastomosis duodenoileal bypass with sleeve gastrectomy (SADI-S). Second, identify the odds between postoperative complications and each surgical procedure.

METHODS

Patients who underwent primary OAGB, RYGB, and SADI-S were identified using the MBSAQIP database of 2020 and 2021. An analysis of patient demographics and 30-day outcomes were compared between these three bypass procedures. In addition, a multilogistic regression for overall complications, blood transfusions, unplanned ICU admissions, readmission, reoperation, and anastomotic leak stratified by surgical procedure was performed.

RESULTS

1607 primary OAGBs were reported between 2020 and 2021. In terms of patient demographics, patients who underwent RYGB and SADI-S showed a higher incidence of comorbidities. On the other hand, OAGB had shorter length of stay (1.39 ± 1.10 days vs 1.62 ± 1.42 days and 1.90 ± 2.04 days) and operative times (98.79 ± 52.76 min vs 125.91 ± 57.76 min and 139.85 ± 59.20 min) than RYGB and SADI-S. Similarly, OAGB showed lower rates of overall complications (1.9% vs 4.5% and 6.4%), blood transfusions (0.4% vs 1.1% and 1.8%), unplanned ICU admission (0.3% vs 0.8% and 1.4%), readmission (2.4% vs 4.9% and 5.0%), and reoperation (1.2% vs 1.9% and 3.1%). A multilogistic regression analysis was performed, RYGB and SADI-S demonstrated higher odds of 30-day complications.

CONCLUSION

The incidence of primary OAGB has increased since its approval by ASMBS, from 0.05% reported between 2015 and 2019 to 0.78% between 2020 and 2021. OAGB had better 30-day outcomes and shorter operative times than RYGB and SADI-S and therefore, could be considered a viable alternative.

Experience of Robotic Complex Revisional Bariatric Surgery in a High-Volume Center

PURPOSE

A revisional bariatric surgery (RBS) is necessary in about 28% of the patients. The role of robotic surgery in RBS is still a subject of debate. We aim to report the outcomes of robotic-assisted RBS at our institution.

MATERIALS AND METHODS

We identified patients who underwent robotic-assisted RBSs between January 1, 2016, and May 31, 2022. We analyzed patient demographics and indications for surgery. Measured outcomes included peri- and postoperative morbidity, comorbidity management, and weight loss outcomes.

RESULTS

A total of 106 patients were included. Primary procedures were adjustable gastric band 44 (41.5%), sleeve gastrectomy 42 (39.6%), Roux-en-Y gastric bypass (RYGB) 18 (17%), duodenal switch (DS) 1 (0.9%), and vertical banded gastroplasty 1 (0.9%). RBSs performed included 85 (78.7%) RYGB, 16 (14.8%) redo-gastrojejunostomy, and 5 (4.6%) DS. The median time to revision was 8 (range 1-36) years, and the main indication was insufficient weight loss (49%). Median length of hospital stay was 2 (range 1-16) days, and 9 (8.5%) patients were readmitted during the first 30 days. Only 4 (3.7%) patients had early Clavien-Dindo grade III or higher adverse events. No anastomotic leaks were documented. Median excess weight loss was 35.1%, 42.23%, and 45.82% at the 6-, 12-, and 24-month follow-up. Of 57 patients with hypertension, 29 (50.9%) reduced their medication dosage, and 20/27 (74.1%) reduced their diabetes mellitus medication dosage. Finally, of the 75 patients with symptoms, 64 (85.3%) reported an improvement after the RBS.

CONCLUSION

Robotic-assisted RBS is feasible, significantly improves patients' comorbidities and symptoms, and leads to considerable weight loss.

Do sleeve gastrectomy and Roux-en-Y gastric bypass have different venous thromboembolism risk factors? Creation of 30-day Bariatric Hypercoagulation Score

BACKGROUND

Venous thromboembolism (VTE) is a major cause of morbidity and mortality after bariatric surgery, most often occurring after discharge within 30 days after surgery.

OBJECTIVES

To determine the risk factors associated with VTE after either sleeve gastrectomy (SG) or Roux-en-Y gastric bypass (RYGB) and to develop a Bariatric Hypercoagulation Score (BHS) to predict 30-day adverse postoperative outcomes.

SETTING

University hospital.

METHODS

Using 2015-2018 data from the Metabolic and Bariatric Surgery Quality Improvement Program, a BHS was created by performing a logistic regression of "venous thromboembolism." The variables with the highest odds ratio (OR) were selected for the SG and RYGB groups. Then, the 30-day outcomes of low-risk (0-1), average-risk (2-3), and high-risk (≥4) BHS were compared.

RESULTS

Similar risk factors for VTE were found in both the SG and RYGB groups; the highest OR was shown by history of deep vein thrombosis (SG: 3.54, RYGB: 3.05). Other related factors in both groups were history of pulmonary embolism, prolonged length of stay, Black race, and male sex. Conversely, unique risk factors such as dialysis (OR 1.81) was found in the SG group; meanwhile, prolonged operative time (OR 1.50) and age >60 years (OR 1.28) were for the RYGB group. When comparing the 30-day outcomes, BHS ≥4 had a significantly higher rate of complications (P < .001).

CONCLUSIONS

SG and RYGB have some risk factors in common for VTE; however, dialysis was associated only with SG, and prolonged operative time and age >60 years were associated only with RYGB. BHS ≥4 showed higher 30-day adverse outcomes. The VTE-correlated variables require special consideration when assessing patients undergoing SG and RYGB.

Do advances in technology translate to improved outcomes? Comparing robotic bariatric surgery outcomes over two-time intervals utilizing the MBSAQIP database

BACKGROUND

This study aims to compare outcomes and utilization of robotics in bariatric procedures across two-time intervals, chosen because they correspond to drastic changes in technology utilization-namely, a new platform and a new stapling device. Outcomes of robotic Roux-en-Y gastric bypass (rRYGB) and robotic sleeve gastrectomy (rSG) across this changing landscape have not been well studied, despite increasing popularity.

METHODS

The MBSAQIP database was analyzed over early (2015-2016) and late (2019-2020) time intervals. Patients who underwent rSG and rRYGB were identified, and the cohorts were matched for 26 preoperative characteristics using Propensity Score Matching Analysis. We then compared 30-day outcomes and bariatric-specific complications between the early and late time frames for rSG and rRYGB.

RESULTS

49,442 rSG were identified: 13,526 cases in the early time frame and 35,916 in the late time frame. The matched cohorts were 13,526 for the two groups. 30-day outcomes showed that in the late time frame, rSG was associated with lower rates of pulmonary complications (0.1% vs 0.3%, p < 0.001), readmissions (2.5% vs 3.6%, p < 0.001), interventions (0.6% vs 1.4%, p < 0.001), reoperations (0.7% vs 1.0%, p = 0.024), length of stay (1.36 ± 1.01 days vs 1.76 ± 1.79 days, p < 0.001), operative time (92.47 ± 41.70 min vs102.76 ± 45.67 min p < 0.001), staple line leaks (0.2% vs 0.4%, p = 0.001) and strictures (0.0% vs 0.2%, p < 0.001). Similarly, 21,933 rRYGB were found: 6,514 cases were identified in the early time frame and 15,419 in the late time frame. The matched cohorts were 6,513 for the two groups. 30-day outcomes revealed that the late time fame rRYGB was associated with lower rates of pulmonary complications (0.1% vs 0.3%, p = 0.012), readmissions (6.3% vs 7.2%, p = 0.050), interventions (2.0% vs 3.1%, p < 0.001), length of stay (1.69 ± 1.46 days vs 2.13 ± 2.12 days p < 0.001), postoperative bleeding (0.4% vs 0.7%, p = 0.001), stricture (0.4% vs 0.8%, p < 0.001) and anastomotic ulcer (0.2% vs 0.4%, p = 0.013).

CONCLUSION

Compared to early robotic bariatric surgery outcomes, a significant reduction in pulmonary complications, readmissions, reoperations, interventions and length of stay were seen in 2019-20 after rSG and rRYGB. Potential contributing factors include increased surgical experience and advances in the robotic platform. A significant recent reduction in staple line leaks with faster operative times associated with rSG suggests that stapling technology has had a positive impact on patient outcomes.

Laparoscopic sleeve gastrectomy to Roux-en-Y gastric bypass conversion versus primary Roux-en-Y gastric bypass: a propensity score matching analysis

BACKGROUND

Secondary bariatric surgery rates have increased, accounting for approximately 19% of the total bariatric cases in the last years, most commonly conversion of sleeve gastrectomy to gastric bypass. Using the MBSAQIP, we evaluate the outcomes of this procedure compared to the primary RYGB surgery.

METHODS

The new variable, conversion of sleeve gastrectomy to RYGB in the 2020 and 2021 MBSAQIP database was analyzed. Patients who underwent primary laparoscopic RYGB and those who underwent laparoscopic sleeve gastrectomy to RYGB conversion were identified. Using Propensity Score Matching analysis, the cohorts were matched for 21 preoperative characteristics. We then compared 30-day outcomes and bariatric-specific complications between primary RYGB and conversion from sleeve gastrectomy to RYGB.

RESULTS

There were 43,253 primary RYGB procedures performed and 6,833 conversions from sleeve gastrectomy to RYGB. The matched cohorts (n = 5912) for the two groups have similar pre-operative characteristics. Propensity-matched outcomes showed that conversion from sleeve gastrectomy to RYGB was associated with more readmissions (6.9% vs 5.0%, p < 0.001), interventions (2.6% vs 1.7%, p < 0.001), conversion to open (0.7% vs 0.2%, p < 0.001), length of stay (1.79 ± 1.77 days vs 1.62 ± 1.66 days, p < 0.001), and operative time (119.16 ± 56.82 min vs 138.27 ± 66.00, p < 0.001). There were no significant differences in mortality (0.1% vs 0.1%, p = 0.405), and bariatric-specific complications such as anastomotic leak (0.5% vs 0.4%, p = 0.585), intestinal obstruction (0.1% vs 0.2%, p = 0.808), internal hernia (0.2% vs 0.1%, p = 0.285) or anastomotic ulcer (0.3% vs 0.3%, p = 0.731) rates.

CONCLUSION

Conversion from sleeve gastrectomy to RYGB is a safe and feasible operation with reasonable outcomes compared with primary RYGB.

Comparative outcomes of bariatric surgery in patients with ESRD on dialysis in the modern era of renal transplantation: analysis using the 2015-2020 MBSAQIP database

BACKGROUND

Severe obesity is a relative contraindication for renal transplantation, therefore bariatric surgery is an important option as a pre-kidney transplant weight loss strategy. However, comparative data regarding postoperative outcomes of laparoscopic sleeve gastrectomy (LSG) or laparoscopic Roux-en-Y gastric bypass (LRYGB) in patients with or without ESRD on dialysis are scarce.

METHODS

Patients between 18- and 80-year-old who underwent LSG and RYGB were included. To determine the outcomes of patient who underwent bariatric surgery with ESRD on dialysis, a 1:4 PSM was performed between the patients with ESRD on dialysis and those without renal disease. The PSM analyses in both groups were performed using 20 preoperative characteristics. Then 30-day postoperative outcomes were assessed.

RESULTS

The operative time and postoperative-LOS were significantly longer in ESRD patients on dialysis compared to those with no renal disease either for LSG (82.37 ± 40.42 vs. 73.62 ± 38.65; P < 0.001, 2.22 ± 3.01 vs. 1.67 ± 1.90; P < 0.001) or for LRYGB (129.13 ± 63.20 vs. 118.72 ± 54.16; P = 0.002, 2.53 ± 1.74 vs. 2.00 ± 1.68; P < 0.001). In the LSG cohort (2137 vs. 8495 matched cases), patients with ESRD on dialysis showed significant increase in mortality (0.7% vs 0.3%; P = 0.019), unplanned ICU admission (3.1% vs 1.3%; P < 0.001), blood transfusions (2.3% vs 0.8%; P 0.001), readmissions (9.1% vs. 4.0%; P < 0.001), reoperations (3.4% vs. 1.2%; P < 0.001), interventions (2.3% vs. 1.0%; P = 0.006). In the LRYGB group (443 vs. 1769 matched cases), patients with ESRD on dialysis showed a significantly higher need for unplanned ICU admission (3.8% vs. 1.4%; P = 0.027), readmissions (12.4% vs. 6.6%; P = 0.011), and interventions (5.2% vs. 2.0%; P = 0.050).

CONCLUSION

Bariatric surgery is a safe procedure for patients with ESRD on dialysis to help them get a kidney transplant. Even though this group experienced a higher incidence of postoperative complications compared to those without kidney disease, the absolute complication rates are low and not associated with bariatric-specific complications. Therefore, ESRD should not be perceived as contraindications to bariatric surgery.

Feasibility and Outcomes of Simultaneous Gastric Bypass with Paraesophageal Hernia Repair in Elderly Patients

BACKGROUND

Paraesophageal hernias (PEH) have a higher incidence in patients with obesity. Roux-en-Y gastric bypass (RYGB) with concomitant PEH repair is established as a valid surgical option for PEH management in patients with obesity. The safety and feasibility of this approach in the elderly population are not well elucidated.

METHODS

We performed a multicenter retrospective cohort study of patients aged 65 years and older who underwent simultaneous PEH repair and RYGB from 2008 to 2022. Patient demographics, hernia characteristics, postoperative complications, and weight loss data were collected. Obesity-related medical conditions' resolution rates were evaluated at the last follow-up. A matched paired t-test and Pearson's test were used to assess continuous and categorical parameters, respectively.

RESULTS

A total of 40 patients (82.5% female; age, 69.2 ± 3.6 years; BMI, 39.4 ± 4.7 kg/m2) with a mean follow-up of 32.3 months were included. The average hernia size was 5.8 cm. Most cases did not require mesh use during surgery (92.5%) with only 3 (7.5%) hernial recurrences. Postoperative complications (17.5%) and mortality rates (2.5%), as well as readmission (2.5%), reoperation (2.5%), and reintervention (0%) rates at 30-day follow-up were reported. There was a statistically significant resolution in gastroesophageal reflux disease (p < 0.001), hypertension (p = 0.019), and sleep apnea (p = 0.014).

CONCLUSIONS

The safety and effectiveness of simultaneous PEH repair and RYGB are adequate for the elderly population. Patient selection is crucial to reduce postoperative complications. Further studies with larger cohorts are needed to fully assess the impact of this surgery on elderly patients with obesity.

Redo fundoplication vs. Roux-en-Y gastric bypass conversion for failed anti-reflux surgery: which is better?

INTRODUCTION

Different techniques have been proposed for reoperation after failed anti-reflux surgery. However, there is no consensus on which should be preferred. We aim to report and compare the outcomes of different revisional techniques for failed anti-reflux surgery.

METHODS

We performed a retrospective analysis of patients who underwent redo fundoplication (RF) or Roux-en-Y gastric bypass (RYGB) conversion after a failed fundoplication at our institution between 2016 and 2021. The primary outcome was long-term presence of reflux or dysphagia following revisional surgery. Secondary outcomes included 30-day perioperative complications as well as long-term use of anti-reflux medication and radiographic recurrence of hiatal hernia (HH).

RESULTS

A total of 165 (median age 63 years, 73.9% female) patients were included. RF was performed in 120 (73 Toupet and 47 Nissen), RYGB in 38, and 7 patients had fundoplication takedown alone. The RYGB group had a significantly higher BMI, and more prior revisional surgeries compared to the other groups. Median operative time and length of stay were longer for RYGB. Twenty (12.1%) patients experienced postoperative complications, with the highest incidence in the RYGB group. Reflux and dysphagia improved significantly for the whole cohort, with the greatest improvement noted with reflux in the RYGB group (89.5% with preoperative reflux vs. 10.5% with postoperative reflux, p =  < .001). On multivariable regression we found that prior re-operative surgery was associated with persistent reflux and dysphagia, whereas RYGB conversion was protective against reflux.

CONCLUSION

Conversion to RYGB may offer superior resolution of reflux than RF, especially for obese patients.

Regulatory Mechanisms of Muscle Mass: The Critical Role of Resistance Training in Children and Adolescent

Muscle mass and strength are subjected to several regulations. We found endocrine signals such as growth hormone, insulin-like growth factor 1, testosterone, thyroid hormones, and glucocorticoids among them. Neural inputs also influence muscle development, modulating mass and strength. Among the external stimuli that modulate these muscular features is physical training such as resistance and endurance training. Specifically, resistance training can mediate an increase in muscle mass by hypertrophy in adults, but the effects in children and adolescents are full of myths for most of the population. However, the evidence shows that the impact of resistance training on children and adolescents is clear and provides a wide range of benefits. However, qualified professionals must be available since exercise prescription and subsequent supervision must follow this population's abilities, needs, and interests.

Improving bitter pit prediction by the use of X-ray fluorescence (XRF): A new approach by multivariate classification

Bitter pit (BP) is one of the most relevant post-harvest disorders for apple industry worldwide, which is often related to calcium (Ca) deficiency at the calyx end of the fruit. Its occurrence takes place along with an imbalance with other minerals, such as potassium (K). Although the K/Ca ratio is considered a valuable indicator of BP, a high variability in the levels of these elements occurs within the fruit, between fruits of the same plant, and between plants and orchards. Prediction systems based on the content of elements in fruit have a high variability because they are determined in samples composed of various fruits. With X-ray fluorescence (XRF) spectrometry, it is possible to characterize non-destructively the signal intensity for several mineral elements at a given position in individual fruit and thus, the complete signal of the mineral composition can be used to perform a predictive model to determine the incidence of bitter pit. Therefore, it was hypothesized that using a multivariate modeling approach, other elements beyond the K and Ca could be found that could improve the current clutter prediction capability. Two studies were carried out: on the first one an experiment was conducted to determine the K/Ca and the whole spectrum using XRF of a balanced sample of affected and non-affected 'Granny Smith' apples. On the second study apples of three cultivars ('Granny Smith', 'Brookfield' and 'Fuji'), were harvested from two commercial orchards to evaluate the use of XRF to predict BP. With data from the first study a multivariate classification system was trained (balanced database of healthy and BP fruit, consisting in 176 from each group) and then the model was applied on the second study to fruit from two orchards with a history of BP. Results show that when dimensionality reduction was performed on the XRF spectra (1.5 - 8 KeV) of 'Granny Smith' apples, comparing fruit with and without BP, along with K and Ca, four other elements (i.e., Cl, Si, P, and S) were found to be deterministic. However, the PCA revealed that the classification between samples (BP vs. non-BP fruit) was not possible by univariate analysis (individual elements or the K/Ca ratio).Therefore, a multivariate classification approach was applied, and the classification measures (sensitivity, specificity, and balanced precision) of the PLS-DA models for all cultivars evaluated ('Granny Smith', 'Fuji' and 'Brookfield') on the full training samples and with both validation procedures (Venetian and Monte Carlo), ranged from 0.76 to 0.92. The results of this work indicate that using this technology at the individual fruit level is essential to understand the factors that determine this disorder and can improve BP prediction of intact fruit.

Is staple line oversewing in patients on chronic anticoagulation during laparoscopic sleeve gastrectomy necessary? Propensity score matching analysis using the 2015-2018 MBSAQIP

BACKGROUND

There is an increased incidence of post-operative bleeding in patients on chronic anticoagulation (CAC). This incited some surgeons to oversew the sleeve staple line as a potentially preventive measure for post-operative bleeding. However, there is no clear evidence to assess the effectiveness of staple line oversewing during laparoscopic sleeve gastrectomy (LSG) in patients with CAC.

METHODS

Using the 2015-2018 metabolic and bariatric surgery accreditation and quality improvement program database, patients between ages 18 and 65 who underwent LSG were included. To investigate the role of CAC, we performed 1:1 propensity score matching (PSM) between the CAC and non-CAC patients. Then, to explore the impact of oversewing, we focused on the CAC patients and divided them into 2 subgroups: oversewing versus non-oversewing. PSM was also performed to compare both subgroups. To avoid confounders, both PSM analyses were performed using 22 preoperative characteristics. 30-day postoperative outcomes including bleeding and blood transfusion requirement were assessed.

RESULTS

402,826 patients underwent LSG. 9148 patients (2.3%) were on CAC. In the CAC cohort (8843 matched cases), the anticoagulated patients showed significant increase in postoperative bleeding (1.2% vs. 0.5%; P < 0.001), blood transfusion requirements (1.7% vs. 0.7%; P < 0.001), unplanned ICU admissions (2.0% vs. 1.3%; P = 0.001), interventions (2.0% vs. 1.5%; P = 0.015), and readmissions (6.2% vs. 4.7%; P < 0.001). 1939 (21.2%) patients on CAC underwent oversewing during the LSG. The operative time was significantly longer in these patients (87.11 ± 40 vs. 76.19 ± 37; P < 0.001). Patients who underwent oversewing showed similar results in 30-day outcomes as those who did not, with no statistical difference, including postoperative bleeding (1.0% vs. 0.9%; P = 0.8) and blood transfusion requirements (1.4% vs. 1.8%; P = 0.9).

CONCLUSION

Incidences of post-operative bleeding and blood transfusion requirements are higher in patients on CAC during the LSG. Oversewing the sleeve staple line leads to longer operative times without additional benefit in 30-day outcomes.

Optimization and Characterization of a Novel Exopolysaccharide from Bacillus haynesii CamB6 for Food Applications

Extremophilic microorganisms often produce novel bioactive compounds to survive under harsh environmental conditions. Exopolysaccharides (EPSs), a constitutive part of bacterial biofilm, are functional biopolymers that act as a protecting sheath to the extremophilic bacteria and are of high industrial value. In this study, we elucidate a new EPS produced by thermophilic Bacillus haynesii CamB6 from a slightly acidic (pH 5.82) Campanario hot spring (56.4 °C) located in the Central Andean Mountains of Chile. Physicochemical properties of the EPS were characterized by different techniques: Scanning electron microscopy- energy dispersive X-ray spectroscopy (SEM-EDS), Atomic Force Microscopy (AFM), High-Performance Liquid Chromatography (HPLC), Gel permeation chromatography (GPC), Fourier Transform Infrared Spectroscopy (FTIR), 1D and 2D Nuclear Magnetic Resonance (NMR), and Thermogravimetric analysis (TGA). The EPS demonstrated amorphous surface roughness composed of evenly distributed macromolecular lumps. GPC and HPLC analysis showed that the EPS is a low molecular weight heteropolymer composed of mannose (66%), glucose (20%), and galactose (14%). FTIR analysis demonstrated the polysaccharide nature (–OH groups, Acetyl groups, and pyranosic ring structure) and the presence of different glycosidic linkages among sugar residues, which was further confirmed by NMR spectroscopic analyses. Moreover, D-mannose α-(1→2) and α-(1→4) linkages prevail in the CamB6 EPS structure. TGA revealed the high thermal stability (240 °C) of the polysaccharide. The functional properties of the EPS were evaluated for food industry applications, specifically as an antioxidant and for its emulsification, water-holding (WHC), oil-holding (OHC), and flocculation capacities. The results suggest that the study EPS can be a useful additive for the food-processing industry.

Programmatic management of patients with pre-extensively drug-resistant tuberculosis in Peru, 2011-2014

BACKGROUND

In Peru, a treatment approach for extensively drug-resistant tuberculosis (XDR-TB) incorporating World Health Organization Group 5 drugs and patient-centred care has achieved 65% success. To extend this approach to pre-XDR-TB patients, we evaluated this population separately.

OBJECTIVE

To assess programmatic management of pre-XDR-TB.

METHOD

Retrospective study using the official national registry from 2011 to 2014. Cases were separately evaluated according to resistance to fluoroquinolones (FQs) (pre-XDR-F) or to second-line injectables (SLIs) (pre-XDR-I).

RESULTS

Of 610 pre-XDR-TB patients, 120 (20%) had pre-XDR-F and 490 (80%) had pre-XDR-I. Pre-XDR-F cases were older (34 years vs. 28 years, P < 0.001) and a higher proportion had previously received two or more regimens (70% vs. 38%, P < 0.001). Among the 452 patients who started treatment in 2011-2013, treatment success was 43.3%, 26.5% were lost to follow-up, 12.1% died and 13.7% failed treatment. Success was higher in pre-XDR-I (48.5%) than pre-XDR-F (21.4%) patients. History of previous treatment (OR 2.23, 95%CI 1.52-3.38) and pre-XDR-F (OR 2.39, CI 1.18-4.83) were associated with unsuccessful outcomes.

CONCLUSION

Programmatic management of pre-XDR-TB has not been successful, particularly in pre-XDR-F patients, with lower rates of success than those achieved in the same setting for XDR-TB. The strategy used for XDR-TB should be extended to pre-XDR-TB patients in Peru.

Residue depletion of oxytetracycline (OTC) and 4-epi-oxytetracycline (4-epi-OTC) in broiler chicken's claws by liquid chromatography-tandem mass spectrometry (LC-MS/MS)

Antibiotics are widely used in poultry production for the treatment of bacterial diseases. However, residues may remain in products and by-products destined for human consumption or animal feeding. The claws of chickens, which are a by-product of the poultry industry, can directly or indirectly enter the food chain as meals destined to feed other productive animals. Thus, it becomes necessary to determine and quantify antimicrobial residues present in this matrix. The objective of the study was to assess the depletion of oxytetracycline (OTC) and its metabolite 4-epi-OTC in broiler chicken's claws. Claws of 32 broilers treated with a therapeutic dosage of 10% OTC during 7 days were analysed. Samples were taken at days 3, 9, 15 and 19 post-treatment. As for the control group, eight broiler chickens were raised under the same conditions. Extraction was carried out through EDTA-McIlvaine buffer, and clean-up employed a SPE C-18 Sep-Pak®. Instrumental analysis was performed through LC-MS/MS. The concentrations of both analytes were determined in claw samples until day 19 post-treatment. Average concentrations were within the LOD (20 μg kg^-1) and LOQ (22 µg kg^-1) for OTC and 84 μg kg^-1 for 4-epi-OTC. Withdrawal times (WDTs) of 39 days for OTC and 54 days for 4-epi-OTC were established in claws based on 95% confidence. These findings demonstrate that claws can be a source of antimicrobial residue entry into the food chain, since the results showed that OTC and its metabolite can be found in chicken's claws for long periods, even exceeding the average lifespan of a broiler chicken.

Pharmacokinetics, efficacy prediction indexes, and residue depletion of ribavirin in Atlantic salmon's (Salmo salar) muscle after oral administration in feed

Ribavirin is an antiviral used in human medicine, but it has not been authorized for use in veterinary medicine although it is effective against infectious salmon anemia (ISA) virus, between others. In this study, we present a pharmacokinetic profile of ribavirin in Atlantic salmon (Salmo salar), efficacy prediction indexes, and the measure of its withdrawal time. To determine the pharmacokinetic profile, fishes were orally administered with a single ribavirin dose of 1.6 mg/kg bw, and then, plasma concentrations were measured at different times. From the time-vs.-concentration curve, Cmax = 413.57 ng/mL, Tmax  = 6.96 h, AUC = 21394.01 μg·h/mL, t1/2  = 81.61 h, and K10  = 0.0421/h were obtained. Ribavirin reached adequate concentrations during the pharmacokinetic study, with prediction indexes of Cmax /IC50  = 20.7, AUC/IC50  = 1069.7, and T>IC50  = 71 h, where IC is the inhibitory concentration 50%. For ribavirin depletion study, fishes were orally administered with a dairy dose of 1.6 mg/kg bw during 10 days. Concentrations were measured on edible tissue on different days post-treatment. A linear regression of the time vs. concentration was conducted, obtaining a withdrawal time of 1966 °C days. Results obtained reveal that the dose of 1.6 mg/kg bw orally administered is effective for ISA virus, originating a reasonable withdrawal period within the productive schedules of Atlantic salmon.

Über die Chemie der Oberfläche des Titandioxids, V Die Oberflächenacidität von Titandioxid und von mit Phosphationen belegtem Titandioxid /On the Chemistry of the Surface of Titaniumoxide, V Surface Acidity of Titanium Dioxide and of Titanium Dioxide Covered with Adsorbed Phosphate Ions

The acidity of surface OH groups on TiO2 (anatase and rutile) was determined using the Benesi titration technique. The most acidic groups have acidity constants (Ho) between 3 and 5. On treatment with solutions of phosphoric acid or phosphates, H2PO4 -ions are adsorbed by ion exchange for basic OH -ions of the surface. The chemisorbed H2PO4 -ions react strongly acidic with an acidity constant Ho between -5.6 and -3.3. Possible reasons for this extreme increase in acidity are briefly discussed.

Influence of biochar amendments on the sorption-desorption of aminocyclopyrachlor, bentazone and pyraclostrobin pesticides to an agricultural soil

The many advantageous properties of biochar have led to the recent interest in the use of this carbonaceous material as a soil amendment. However, there are limited studies dealing with the effect of biochar on the behavior of pesticides applied to crops. The objective of this work was to determine the effect of various biochars on the sorption-desorption of the herbicides aminocyclopyrachlor (6-amino-5-chloro-2-cyclopropyl-4-pyrimidinacarboxylic acid) and bentazone (3-isopropyl-1H-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide) and the fungicide pyraclostrobin (methyl 2-[1-(4-chlorophenyl) pyrazol-3-yloxymethil]-N-methoxycarbanilate) to a silt loam soil. Aminocyclopyrachlor and bentazone were almost completely sorbed by the soils amended with the biochars produced from wood pellets. However, lower sorption of the herbicides was observed in the soils amended with the biochar made from macadamia nut shells as compared to the unamended soil, which was attributed to the competition between dissolved organic carbon (DOC) from the biochar and the herbicides for sorption sites. Our results showed that pyraclostrobin is highly sorbed to soil, and the addition of biochars to soil did not further increase its sorption. Thus, addition of biochars to increase the retention of low mobility pesticides in soil appears to not be necessary. On the other hand, biochars with high surface areas and low DOC contents can increase the sorption of highly mobile pesticides in soil.

Effect of soil organic amendments on the behavior of bentazone and tricyclazole

The effect of soil amendment with different organic residues from olive oil production on the sorption and leaching of two pesticides used in rice crops (bentazone and tricyclazole) was compared in order to understand their behavior and to improve soil properties by recycling an abundant agricultural residue in Andalucía (S. Spain). A residue from olive oil production (AJ), the organic compost derived from this organic waste (CA) and a biochar (BA) made from CA were used. A soil devoted to rice cultivation, IFAPA (I), was amended at 2% (w/w) of each amendment individually (I+AJ, I+CA and I+BA). In order to evaluate the effect of dissolved organic matter (DOM) from these amendments on bentazone and tricyclazole behavior, the DOM from the amendments was extracted, quantified and characterized by fluorescence spectroscopy and FT-IR. The affinity of DOM for soil surfaces was evaluated with (I) soil and two other soils of different physicochemical properties, ARCO (A) and GUAD (G). These studies revealed differences in DOM quantity, quality and affinity for the used soils among amendments which can explain the different sorption behavior observed for tricyclazole in the amended soils. Leaching assays under saturated/unsaturated conditions revealed a slight delay of bentazone in I+CA and I+BA soils when compared to I+AJ, that can be related to the higher DOM content and much lower specific surface area of AJ. In contrast, tricyclazole was not detected in any of the leachates during the leaching assay. Extraction of tricyclazole residues from soil columns showed that the fungicide did not move below 5cm in the higher sorptive systems (I+CA, I+BA). The sorption of DOM from amendments on soil during the transport process can decrease the mobility of the fungicide by changing the physicochemical properties of the soil surface whose behavior may be dominated by the adsorbed DOM.

Nutritional and physical characteristics of commercial hand-feeding formulas for parrots

Hand-rearing is a common practice for the propagation of captive psittacines, however, research on their nutrition is limited and the requirements of growing chicks are not well understood. The nutrition of 15 commercially available parrot hand-feeding formulas was compared with the average content of the crops of free living Scarlet Macaw (Ara macao) chicks, as well as with the requirements of 6- to 12-week-old leghorn chickens. When the formulas were prepared for a 1-week-old chick, all except three maintained >90% of solids in suspension after 15 min and >60 after 30 min. On average the formulas had a similar metabolizable energy density as wild macaw crop samples. The concentration of crude protein in the formulas was higher than that of the crop sample average, while the crude fat was lower than the average crop samples. More than 50% of the formulas had concentrations of K, Mg, and Mn less than the crop sample average, and Ca and Na concentrations below the requirements established for 6- to 12-week-old leghorn chickens. For >45% of the formulas the concentrations of arginine, leucine, and methionine + cystine were below the requirements of 6- to 12-week leghorns. When commercial formulas were prepared according to the manufacturer's instructions, the different dilutions greatly magnified the nutritional differences among them. Overall, the inconsistency in the nutrient concentrations among the formulas suggests that there is no consensus among manufacturers of the correct nutrition for growing psittacines and the industry could benefit from continued research in this area.

Environmental behavior of the enantiomers of the chiral fungicide metalaxyl in Mediterranean agricultural soils

Improving the existing knowledge on the enantioselectivity of processes affecting chiral pesticide enantiomers in the environment is necessary to maximize the efficacy and minimize the environmental impact caused by the use of pesticides with chiral properties. In this work, the enantioselectivity of the sorption, degradation, and leaching processes of the chiral fungicide metalaxyl in three slightly alkaline, agricultural soils from southern Spain was studied. Batch sorption experiments indicated that the sorption of racemic-metalaxyl on soils, their clay (<2 μm) fractions, and a number of model sorbents simulating naturally-occurring soil colloidal particles was non-enantioselective; the S-enantiomer was sorbed to the same extent as the R-enantiomer on all soil materials. Soil incubation experiments revealed that the R-enantiomer of metalaxyl was degraded faster than the S-enantiomer in all three soils, but the extent and enantioselectivity of metalaxyl degradation was soil-dependent, occurring more slowly and with less enantioselectivity in the fine-textured soil (soil 1) than in the coarse-textured soils (soils 2 and 3). For soils 2 and 3, S- and R-metalaxyl dissipation data were very well described by single first-order kinetics, whereas for soil 1 dissipation data were better fitted by two coupled first-order equations. It is suggested that sorption and entrapment of metalaxyl enantiomers in the abundant small-size pores of soil 1 (i.e., pore radius<100 nm) could have resulted in a fraction of the fungicide of reduced bioavailability, and consequently, protected from enantioselective degradation. Metalaxyl leaching through soil columns was also enantioselective; the concentration of S-metalaxyl in all leachates collected was greater than that of R-metalaxyl. Despite being non-enantioselective, sorption influenced the enantioselectivity of metalaxyl leaching, as it determined the residence time of the fungicide within the soil column, and consequently, the extent and enantioselectivity of its degradation during leaching.

Organo/LDH nanocomposite as an adsorbent of polycyclic aromatic hydrocarbons in water and soil-water systems

Polycyclic aromatic hydrocarbons (PAHs) are considered as priority pollutants because of their high risk to human health. In this paper, we addressed the issue of using hydrotalcite-based nanocomposites as adsorbents of six low molecular weight PAHs (acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene and pyrene) to reduce their negative effects on the environment. A nanocomposite (HT-DDS) was prepared by intercalating the organic anion dodecylsulfate (DDS) in a Mg-Al hydrotalcite (HT), and then characterized using several analytical techniques. A Mediterranean soil was selected for being a high-risk scenario of groundwater contamination by leaching of pollutants. The nanocomposite displayed enhanced affinity for the PAHs in water as compared to carbonate-hydrotalcite (HTCO(3)) and its calcined product (HT500), and showed a high irreversibility of the adsorption process (hysteresis coefficient, H<0.15). The results revealed an increase of the pollutants retention in the soil by the addition of the nanocomposite that depended on the nanocomposite application rate and also on the hydrophobicity of each PAH. Accordingly, the use of HT-DDS as an amendment or barrier in contaminated soil is proposed for reducing the mobility of PAHs and, consequently, the adverse effect derived from rapid transport losses of the pollutants to the adjoining environmental compartments.

Effect of olive-mill waste addition to soil on sorption, persistence, and mobility of herbicides used in Mediterranean olive groves

Laboratory and field experiments were conducted to evaluate the effect of olive-mill waste (OMW) addition to a Mediterranean olive grove soil on sorption, persistence, and mobility of two herbicides which are simultaneously applied for weed control in olive groves: terbuthylazine (TA) and fluometuron (FM). Laboratory batch sorption experiments showed that OMW addition to the soil at rates of 5 and 10% (w/w) greatly enhanced the sorption of both herbicides, thus suggesting that amendment with OMW could be useful to enhance the retention and reduce the mobility of FM and TA in the soil. Incubation experiments showed that OMW increased the persistence of FM and had little effect on the long persistence of TA in the soil studied. A demonstration field experiment was also conducted in field plots with a slope of about 5%, either unamended or amended with OMW at a rate of 10 kg m⁻², and then treated with a commercial formulation containing a mixture of TA and FM. Extraction of field soil samples, taken from different soil depths (0-5, 5-10, 10-20, and 20-30 cm) at different times after herbicide application, showed that both TA and FM moved deeper in unamended soil than in OMW-amended soil, and that OMW addition affected the persistence of FM in the toplayer, increasing its half-life from 24 to 58 days, while having little effect on the persistence of TA. Thus, data obtained under real field conditions were consistent with those obtained under controlled laboratory conditions. Preliminary herbicide runoff data indicated that the total herbicide runoff losses were also reduced upon OMW addition. Addition of OMW could be beneficial in reducing the mobility of TA and FM in olive grove soils, and also in increasing the persistence of FM in soils where this herbicide could be rapidly degraded.

Montmorillonite-chitosan bionanocomposites as adsorbents of the herbicide clopyralid in aqueous solution and soil/water suspensions

Montmorillonite (SWy-2)-chitosan bionanocomposites (SW-CH) were prepared following different methodologies, characterized, and assayed as adsorbents of the herbicide clopyralid (3,6-dichloropyridine-2-carboxylic acid) in aqueous solution and soil/water suspensions, to assess the potential of the materials to prevent and remediate soil and water contamination by anionic pesticides. The SW-CH bionanocomposites were good adsorbents for the herbicide at pH levels where both the anionic form of the herbicide (pK(a)=2.3) and the cationic form of CH (pK(a)=6.3) predominated. The performance of the SW-CH bionanocomposites as adsorbents of clopyralid depended on the amount and arrangement of chitosan in the samples. Clopyralid adsorption was rapid and mostly linear up to herbicide concentrations as high as 0.5mM. High salt concentrations (0.1M NaCl) promoted desorption of the adsorbed pesticide from SW-CH, strongly suggesting that adsorption of clopyralid occurred primarily through an ion exchange mechanism on positively charged CH sites at the montmorillonite surface. Amendment of an acidic soil (pH=4.5) with SW-CH at rates of 5% and 10% led to a significant increase in clopyralid adsorption, whereas this effect was negligible when SW-CH was added to an alkaline soil (pH=8.0), reflecting the absence of positively charged sites in SW-CH at high pH values. Montmorillonite-CH bionanocomposites can be useful as adsorbents for the removal and/or immobilization of anionic pesticides in soil and water under mild acidic conditions.

Predicted metabolizable energy density and amino acid profile of the crop contents of free-living scarlet macaw chicks (Ara macao)

Hand rearing of neonates is a common practice for the propagation of psittacines. However, nutritional requirements for their growth and development are not well understood, and malnutrition is common. We analysed the amino acid (AA) profile of the crop contents of 19 free-living scarlet macaw (Ara macao) chicks, 19-59 days old. Predicted metabolizable energy (PME) density was 16.9 MJ/kg DM and true protein (total AA protein) 8.3 g/MJ PME. Crude protein (CP) was 10.0 g/MJ PME, lower than the requirements of 0- to 12-week-old leghorn chicks but not different than the requirements of growing budgerigars (Melopsittacus undulatus) and lovebirds (Agapornis spp.). The mean concentrations of leucine, isoleucine, threonine, lysine (Lys) and methionine on a PME basis were below the minimum requirements of 0- to 12-week-old leghorn-type chicks. The calculated PME density of the samples did not vary with age. However, there was a significant negative correlation between the average age of the chicks and the Lys concentration. We conclude that the lower CP and AA densities compared with poultry could result from a combination of (i) differences in the essential AA composition of the body tissues, (ii) adaptations that allow the birds to grow on low-protein food sources and (iii) suboptimal nutrition of these free-ranging chicks.

Paciente VIH positivo con tuberculosis sistémica y lesiones osteolíticas de la calvaria, semejando mieloma múltiple

Varón de 33 años, soltero, sin ocupación fija, promiscuo, con historia de relaciones homosexuales, ingesta crónica de alcohol, consumo de tabaco, marihuana, pasta básica y clorhidrato de cocaína, desde los 18 años. Infectado por el virus de la inmunodeficiencia humana, recibía tratamiento irregular con terapia antirretroviral de gran actividad (Targa) entre 2006 y 2008, regularizada en los últimos 12 meses. Por presentar bacilo ácido alcohol resistente (BAAR) pansensible en esputo, inició en junio 2008 tratamiento antituberculoso [2RHZE/4(HR)2)], retirándosele la medicación 6 meses después por presentar BAAR pulmonar negativo. En marzo de 2009, percibió dolor lumbar intenso, dificultad para caminar, hipertrofia de ganglios cervicales, tos, fiebre. Un cultivo de secreción ganglionar cervical descubrió M. tuberculosis resistente a rifampicina. La imagenología mostró lesiones osteolíticas múltiples en cráneo y vértebras dorsolumbares y tumefacciones renitentes en cuero cabelludo, antebrazo derecho y parrilla costal izquierda. Tras descartarse mieloma múltiple y metástasis cancerosas, se añadió tratamiento antituberculosis multidrogo resistente al Targa, notándose dos meses después involución de las tumefacciones renitentes, de la fiebre y mejoría del estado general. Tras 16 meses de tratamiento supervisado, el paciente aumentó 7 kg de peso, habiendo desaparecido la sintomatología que presentaba. Se discute la fisiopatología de las lesiones osteolíticas cráneo-vertebrales en un paciente con coinfección por el virus de la inmunodeficiencia humana y tuberculosis.

Study of enrofloxacin and flumequine residues depletion in eggs of laying hens after oral administration

Two groups of laying hens (each n=12) were administered 10 mg/kg enrofloxacin (ENRO) (group A) or 26.6 mg/kg flumequine (FLU) (group B) by gastric catheter daily for five consecutive days. A third group (n=6) was untreated controls. Eggs were collected from day one of treatment and up to 30 days after withdrawal of the drug. Egg white and yolk from each egg were separated, and ENRO, its metabolite ciprofloxacin (CIP) and FLU residues were analysed by a high-performance liquid chromatography method with fluorescence detection. The sum of ENRO and CIP was detectable in egg white on the first day of treatment in high-level concentrations (2007.7 μg/kg) and remained steady during administration. In egg yolk, residues were detectable at day one in lower concentrations (324.4 μg/kg), increasing to the end of treatment. After treatment, these residues decreased and were detectable up to day 8 in egg white, and day 10 in yolk. FLU residues during drug administration in white were detectable in high concentrations from day one to five (6788.4-6525.9 μg/kg), and in yolk, concentrations were lower during administration (629.6-853.9 μg/kg). After drug withdrawal, FLU residues remained longer in egg white (30 days) than in yolk (26 days). For both drugs, differences of concentrations between matrices were significant.

Multi-source water pollution in a highly anthropized wetland system associated with the estuary of Huelva (SW Spain)

Major ions, nutrients, trace elements and pesticides distribution were studied in a coastal wetland heavily impacted by human development in Spain. Past land use has altered the local hydrodynamics leading to the partitioning of the ecosystem into a tideland subject to marine influence, and an artificial freshwater reservoir created by stream impoundment. The tideland stretch is flooded twice a day with a heavy metal plume that emerges from the mine-polluted estuary of Huelva and propagates landward depicting the same dispersal trend of major seawater ions. Additionally, the tidal channel receives acid discharges from industrial point sources that contribute to metal enhancement. The impounded area and stream tributaries are affected by agrochemicals runoff (nitrate, phosphate, pendimethalin, simazine, diuron and therbuthylazine) from surrounding agricultural lands. The tidal regime plays a crucial role in the transport and dispersion of pollutants, except in the artificial reservoir where freshwater exhibits a seasonal mineralization pattern.

Layered double hydroxides as adsorbents and carriers of the herbicide (4-chloro-2-methylphenoxy)acetic acid (MCPA): systems Mg-Al, Mg-Fe and Mg-Al-Fe

Hydrotalcite-like compounds [Mg(3)Al(OH)(8)]Cl x 4H(2)O; [Mg(3)Fe(OH)(8)]Cl x 4H(2)O; [Mg(3)Al(0.5)Fe(0.5)(OH)(8)]Cl x 4H(2)O (LDHs) and calcined product of [Mg(3)Al(OH)(8)]Cl x 4H(2)O, Mg(3)AlO(4.5) (HT500), were studied as potential adsorbents of the herbicide MCPA [(4-chloro-2-methylphenoxy)acetic acid] as a function of pH, contact time and pesticide concentration, and also as support for the slow release of this pesticide, with the aim to reduce the hazardous effects that it can pose to the environment. The information obtained in the adsorption study was used for the preparation of LDH-MCPA complexes. The results showed high and rapid adsorption of MCPA on the adsorbents as well as that MCPA formulations based on LDHs and HT500 as pesticide supports displayed controlled release properties and reduced herbicide leaching in soil columns compared to a standard commercial MCPA formulation. Thereby, we conclude that the LDHs employed in this study can be used not only as adsorbents to remove MCPA from aqueous solutions, but also as supports for the slow release of this highly mobile herbicide, thus controlling its immediate availability and leaching.

Effectiveness of glyphosate and imazamox on the control of the invasive cordgrass Spartina densiflora

The south-American cordgrass, Spartina densiflora, has become the dominant plant species on recent tidal marsh restorations in the Doñana National Park (SW Spain). We examined the effect of different doses of glyphosate (720-7200 g a.i. ha(-1)) and imazamox (20-68 g a.i. ha(-1)) on growth and photosynthetic apparatus of S. densiflora. Imazamox had no effect on neither on growth nor photosynthetic apparatus of S. densiflora. On the contrary, glyphosate inhibited photochemical efficiency of photosynthesis from day one. Net photosynthetic rate, stomatal conductance and photosynthetic pigments and the number of new tillers were reduced. Glyphosate at high doses (ca. 7200 g a.i. ha(-1)) could be an appropriate method of control, since it has a negative effect over the photosynthetic apparatus and growth of S. densiflora. Furthermore, glyphosate and its main metabolite, AMPA, were not extracted from the soil, since they were retained by the very high iron and aluminum oxide content of this soil.

Depletion study of enrofloxacin and its metabolite ciprofloxacin in edible tissues and feathers of white leghorn hens by liquid chromatography coupled with tandem mass spectrometry

To ensure delivery of safe foods to consumers, withdrawal times for drugs must be respected according to the maximum residual limits established by regulatory agencies. Because of availability and price, feather meal is currently incorporated into animal feed as a protein source for farm species. Few data are available on residual drugs in feathers from treated animals. A depletion study was performed with laying hens treated intramuscularly with 5% enrofloxacin (Enromic) at 10 mg/kg body weight over 3 days. Thirty-three birds were treated and slaughtered at different times between 6 and 216 h after treatment; and samples of muscle plus skin, liver, kidney, and feathers were collected. High-performance liquid chromatography coupled with a tandem mass spectrometry method was validated before sample analysis to determine the decision limit, detection capability, recovery, and precision. Liver was the edible tissue with the slowest drug depletion. A withdrawal time of 6 days was calculated based on European Union maximum residual limits (100 microg/kg). A withdrawal time of 9 days was calculated based on Japan maximum residual limits (10 microg/kg). Enrofloxacin plus ciprofloxacin concentrations in feathers remained high through all sampling periods. Thus, feathers from treated animals should not be fed to food-producing animals.

Isolation and molecular characterization of quinolone resistant spp. from poultry farms

The antimicrobial susceptibility of 94 Salmonella strains isolated from different poultry farms in Chile (broiler and laggin hens) were analyzed by the dilution plates method. Thirty-nine of them were resistant to flumequine, nalidixic acid and oxolinic acid with MIC values higher than 64 microg/ml. These quinolone resistant strains were analyzed in order to determine the presence of mutations in the QRDR region of gyrA gene by AS-PCR-RFLP analysis. 51.3% of the strains showed mutations at codon Ser 83 and 41.0% showed mutations at codon Asp 87. No mutations were observed on codon Gly 81. These mutations were confirmed by sequenciation of one representative strain from different RFLP pattern. Likewise, no double mutations were observed. Over 90% of the quinolone resistant strains presented mutations at the QRDR region of the gyrA gene. Three phenotypically resistant strains did not show any mutations on the QRDR region of gyrA gene. However, other molecular resistant mechanism could be involve. This is the first study that demonstrate the emergency of quinolone and fluoroquinolone resistance in Chilean Salmonella strains isolated from poultry thus indicating the requirement of monitoring programmes in veterinary medicine.

Quasielastic 3He(e,e'p)2H reaction at Q2 = 1.5 GeV2 for recoil momenta up to 1 GeV/c

We have studied the quasielastic 3He(e,e(')p)2H reaction in perpendicular coplanar kinematics, with the energy and the momentum transferred by the electron fixed at 840 MeV and 1502 MeV/c, respectively. The 3He(e,e(')p)2H cross section was measured for missing momenta up to 1000 MeV/c, while the A(TL) asymmetry was extracted for missing momenta up to 660 MeV/c. For missing momenta up to 150 MeV/c, the cross section is described by variational calculations using modern 3He wave functions. For missing momenta from 150 to 750 MeV/c, strong final-state interaction effects are observed. Near 1000 MeV/c, the experimental cross section is more than an order of magnitude larger than predicted by available theories. The A(TL) asymmetry displays characteristic features of broken factorization with a structure that is similar to that generated by available models.

Measurement of the 3He(e,e'p)pn reaction at high missing energies and momenta

Results of the Jefferson Lab Hall A quasielastic 3He(e,e'p)pn measurements are presented. These measurements were performed at fixed transferred momentum and energy, q=1502 MeV/c and omega=840 MeV, respectively, for missing momenta p(m) up to 1 GeV/c and missing energies in the continuum region, up to pion threshold; this kinematic coverage is much more extensive than that of any previous experiment. The cross section data are presented along with the effective momentum density distribution and compared to theoretical models.

Hexazinone and simazine dissipation in forestry field nurseries

Hexazinone and simazine field dissipation was studied in two different soils from Spain (Toledo and Burgos), devoted to forest nurseries for Pinus nigra. Laboratory experiments (adsorption-desorption isotherms, leaching experiment and degradation study) were carried out to determine possible mechanisms of dissipation. Higher adsorption was observed for hexazinone in Toledo (KfT = 0.69) compare to in Burgos soil (KfB = 0.20) probably due to the higher organic matter (OM) content of Toledo soil. No differences in adsorption were obtained for simazine in both soils (KfT = 1.27; KfB = 1.34). In every case, adsorption was higher for simazine than for hexazinone, in both soils. The total recovery of hexazinone in the leachates from handpacked soil columns was higher in Burgos (100%) than in Toledo (80%), because of the larger adsorption of hexazinone in this last soil. No differences in simazine leaching between both soils were found, although the total amount of pesticide recovered in leachates (40% in the two soils) was lower for simazine than for hexazinone. Finally, lower degradation was found in Burgos (t1/2 = 91 d) vs Toledo (t1/2 = 47 d), directly related with the high OM content of Toledo. No half-life was calculated for simazine in Toledo because no changes in herbicide soil content were observed during the period of time studied. In the case of Burgos, the half-life for simazine was 50 days. The field residues study showed larger persistence of simazine than hexazinone mainly due to the higher adsorption and lower mobility of simazine in the two soils. The lower persistence of hexazinone in Toledo soil than in Burgos soil is related to the larger rainfall occurred in this soil besides the higher degradation of this herbicide observed in Toledo soil. The much lower temperature in Burgos than in Toledo soil during winter contribute to the higher persistence of the two herbicides in Burgos soil.

Adsorption of imidazolinone herbicides on smectite-humic acid and smectite-ferrihydrite associations

Adsorption of imazapyr (IMZ), imazethapyr (IMZT), and imazaquin (IMZQ) was studied on two smectite-humic acid and two smectite-ferrihydrite binary systems prepared by treating a Wyoming smectite with a humic acid extracted from soil (4 and 8% w/w of the smectite) and with just-precipitated synthetic ferrihydrite (8 and 16% w/w of the smectite). Adsorption of the three herbicides on the smectite was not measurable at pH >4.5, presumably because of negative charges on the surface of the smectite. Adsorption on the smectite-humic acid systems was also not measurable, presumably because of negative charges on the surface, despite the high affinity of the three herbicides for humic acid, the adsorption order of which was IMZ < IMZT << IMZQ. Adsorption decreased in the order IMZ < IMZT < IMZQ on the smectite-ferrihydrite systems and IMZQ < IMZT < IMZ on ferrihydrite, although here the differences were small. These results show that even though pure smectite cannot adsorb herbicides, it modifies the adsorption capacity of ferrihydrite. The mutual interaction of active phases such as humic acid, ferrihydrite, and smectite alters the characteristics of the resulting surface and hence the adsorption process. Investigations of herbicide adsorption have been seen to produce more reliable results if conducted on polyphasic systems rather than on single soil components.

Organoclays for controlled release of the herbicide fenuron

Organoclays were assayed as matrices in which to associate herbicides, with the aim of decreasing product losses that could give rise to water contamination from agricultural activities. Fenuron was selected as model of a very mobile and highly water-soluble herbicide. Two different organoclays of high (A-HDT) and low (H-C18) reversible fenuron sorption were selected. Herbicide-organoclay complexes were prepared from the two organoclays and with two different fenuron contents (20 and 40 g AI kg-1) and two different mixing times, so as to form a series of weak and strong complexes. The release of fenuron from those complexes into water and water/soil suspensions gave values of T50 (time to release 50% of the fenuron content) ranging from 0.3 min to 2400 h. The total fenuron released in these closed systems ranged from 48 to 80% of the fenuron in the complex. The organoclay type (high or low sorptivity) had the greatest influence on fenuron release, followed by the strong or weak complex, suggesting that herbicide-organoclay interactions are the main factors controlling release. Soil column leaching experiments showed fenuron-organoclay complexes to be effective in reducing the peak herbicide concentration in the leachate to a half (6 microns) or a quarter (3 microns) of that obtained from the free technical compound (12 microns). Herbicide lost through leaching was reduced from 78% for the free technical fenuron to 50-30%, depending on the organoclay used as carrier and the strength of the complex. Bioassay with ryegrass showed that the weak fenuron/H-C18 complex (40 g AI kg-1) gave the same herbicidal activity as technical fenuron. The potential suitability of low-sorptive organoclays for conferring slow-release properties on the fenuron complex has been demonstrated.

Adsorption of imidazolinone herbicides on ferrihydrite-humic acid associations

Adsorption of the imidazolinone herbicides imazapyr, imazethapyr and imazaquin was studied on two binary systems (ferrihydrite-humic acid) prepared by treating ferrihydrite (Fh) immediately after its precipitation with a soil humic acid (HA) at different loadings (4% and 8% HA content), and on a blank ferrihydrite sample prepared in the same way, but without HA addition. Imidazolinone adsorption on pure Fh and on the 4% Fh-HA decreased with increasing of the herbicide hydrophobicity (imazaquin<imazethapyr<imazapyr), whereas on the 8% Fh-HA system the order of adsorption was nearly the same, indicating that higher amounts of HA on Fh increase the hydrophobicity of the surface and thus increases its affinity for the herbicides, specially for imazaquin. Adsorption was also enhanced by low pH values and slight changes in pH enhanced the contribution of each component in adsorption. Both the nature of the surface exposed and its ability to interact with herbicides are greatly altered by the mutual interaction of Fh and HA. The results show that albeit artificial polyphasic associations are more representative of the real situation than single model components and are thus better indicators of the behaviour of a given herbicide in the soil.

Sorption and photolysis studies in soil and sediment of the herbicide napropamide

The influence of soil and sediment composition on sorption and photodegradation of the herbicide napropamide [N,N-diethyl-2-(1-naphthyloxy)propionamide] was investigated. Five soils and one sediment were selected for this study and the clay fractions were obtained by sedimentation. Sorption-desorption was studied by batch equilibration technique and photolysis in a photoreactor emitting within 300-450 nm wavelength with a maximum at 365 nm. Sorption increased with clay content and was not related to organic matter content. High irreversibility of sorption was related to the greater montmorillonite content. The presence of soil or sediment reduced photolysis rate due to screen effect and this process did not depend on solid composition but on particle size distribution.

Fenuron sorption on homoionic natural and modified smectites

The adsorption isotherms of fenuron (1,1-dimethyl-3-phenylurea) on three smectites (SWy and SAz montmorillonites and SH hectorite) differing in their layer charge (SH<SWy<SAz) and saturated with several inorganic and organic cations were determined. The isotherms and sorption parameters from Freundlich equation indicate low adsorptivity on inorganic clays, but medium sorption in organoclays (OCls). Fenuron adsorption on homoionic smectites increases with decreasing layer charge and hydratation power of the inorganic exchangeable cation (except Fe3+), indicating that fenuron adsorbs as neutral molecule on uncharged siloxane surface by hydrophobic bonding, with some contribution of polar bond (fenuron C=O group and water associated to exchangeable cation). In the case of Fe3+-saturated smectite fenuron protonation, provided by the interlayer acidic environment, promotes further sorption of fenuron as cationic form. The sorption on organoclays is enhanced via hydrophobic interaction with organocations, which is favoured for high layer charge and basal spacing and organocation saturation close to CEC. Quaternary alkylamonium is more efficient in high layer charge smectite, whereas primary alkylammonium is more efficient in medium charge smectite. The low values of the maximum sorption obtained with homoionic inorganic and organic smectites (100 and 5000 micromol/Kg) represent one fenuron molecule for each 2000-200 exchange sites and indicate that fenuron sorption is mainly associated to the outer exchange sites. This low adsorptivity of fenuron, as consequence of its high water affinity (high water solubility) would suggest high mobility of fenuron in natural soil and water systems.

Organosmectites as sorbent and carrier of the herbicide bentazone

Sorption isotherms of bentazone on diverse organoclays (OCls) were measured at aqueous concentrations from 25 to 1500 microM. Sorption on organophilic OCls, OCls with large quaternary alkylammonium groups, i.e. hexadecyltrimethylammonium (AHDT) and dioctadecyldimethylammonium (ADOD), were compared to that on sorptive OCls, which have large primary alkylammonium (octadecylammonium, AC18) and small quaternary alkylammonium (phenyltrimethylammonium, PTA) groups. The organophilic OCls showed much higher sorption (AHDT Kd = 682-1789; ADOD Kd = 838-1728) than the sorptive OCls (AC18 Kd = 38-40; PTA Kd = 0), suggesting hydrophobic bentazone-organocation interactions as the main mechanism responsible for sorption. The incubation of the two organophilic OCls with soil contaminated with bentazone showed that availability of the herbicide decreased almost instantaneously from 124 microg g(-1) to 1 microg g(-1). Bentazone sorbed on the OCl, and thus immobilized, was partially extractable with CaCl2/methanol solution suggesting its potential bioavailability. Two OCls, with high and low sorptions, were assayed as herbicide carriers by preparing bentazone-OCl complexes and monitoring their herbicide release in water and soil-water suspensions. These bentazone-OCl complexes released 20-80% of their bentazone content, depending of the sorbent capacity and the bentazone-OCl interaction. Results of this work show that by varying the sorptive properties of OCls, they can be used to immobilize pesticide in a contaminated soil and to protect soil and water by using OCl as pesticide carriers in slow release formulations.

Natural soil colloids To retard simazine and 2,4-D leaching in soil

Natural or synthetic sorbents for pesticides can be used to reduce contamination of soils and natural waters. The sorption of simazine and 2,4-D on montmorillonite minerals has been studied and their potential use to retard pesticide leaching in soil evaluated. Simazine and 2,4-D did not sorb on high-layer charge montmorillonite, whereas sorption on the lower layer charge montmorillonite SWy varied depending on the saturating cation. Simazine sorption increased in the order Ca(2+)SWy << K(+)SWy < Fe(3+)SWy. Simazine molecules sorb on hydrophobic microsites of the montmorillonite. Once protonated, further sorption through cation exchange takes place in the interlamellar space of the montmorillonite, as corroborated by X-ray diffraction and FT-IR studies. 2,4-D does not sorb on K(+)SWy or Ca(2+)SWy, but does sorb on Fe(3+)SWy, because the acidic character of this sorbent allows the molecular form of 2, 4-D to sorb by hydrogen bonding and/or by hydrophobic interactions. Leaching experiments in hand-packed soil columns indicate that simazine and 2,4-D application as a complex with FeSWy renders later breakthrough and lower maximum concentration peaks, and the total herbicide leached is lower than when applied as the pure analytical grade compound. These results suggest the possible use of natural soil colloids as sorbents for herbicides such as simazine and 2,4-D to retard pesticide leaching in soil, thus reducing their ground water contamination potential.

Sorption and desorption of triadimefon by soils and model soil colloids

Sorption-desorption of the azole fungicide triadimefon [1-(4-chlorophenoxy)-3,3-dimethyl-1-(1H-1,2, 4-triazol-1-yl)-2-butanone] on eight soils and a series of single, binary, and ternary model soil colloids was determined using the batch equilibration technique. Regression analysis between Freundlich sorption coefficients (K(f)) and soil properties suggested that both clay and organic C (OC) were important in triadimefon sorption by soils, with increasing importance of clay for soils with high clay and relatively low OC contents. Triadimefon sorption coefficients on soil were not significantly affected by the concentration of electrolyte or the presence of soluble soil material in solution, but they were highly dependent on the soil:solution ratio due to the nonlinearity of triadimefon sorption on soil. Freundlich sorption isotherms slopes were very similar for all soils (0.75 +/- 0.02). Desorption did not greatly depend on the concentration at which it was determined and showed higher hysteresis for more sorptive soils. Results of triadimefon sorption on model sorbents supported that both humic acid and montmorillonite-type clay constituents contribute to triadimefon retention by soil colloids.

Phytobilin biosynthesis: cloning and expression of a gene encoding soluble ferredoxin-dependent heme oxygenase from Synechocystis sp. PCC 6803

The phytobilin chromophores of phycobiliproteins and phytochromes are biosynthesized from heme in a pathway that begins with the opening of the tetrapyrrole macrocycle of protoheme to form biliverdin IX alpha, in a reaction catalyzed by heme oxygenase. A gene containing an open reading frame with a predicted polypeptide that has a sequence similar to that of a conserved region of animal microsomal heme oxygenases was identified in the published genomic sequence of Synechocystis sp. PCC 6803. This gene, named ho1, was cloned and expressed in Escherichia coli under the control of the lacZ promoter. Cells expressing the gene became green colored due to the accumulation of biliverdin IX alpha. The size of the expressed protein was equal to the predicted size of the Synechocystis gene product, named HO1. Heme oxygenase activity was assayed in incubations containing extract of transformed E. coli cells. Incubations containing extract of induced cells, but not those containing extract of uninduced cells, had ferredoxin-dependent heme oxygenase activity. With mesoheme as the substrate, the reaction product was identified as mesobiliverdin IX alpha by spectrophotometry and reverse-phase HPLC. Heme oxygenase activity was not sedimented by centrifugation at 100, 000 g. Expression of HO1 increased several-fold during incubation of the cells for 72 h in iron-deficient medium.