Perioperative glutamine supplementation restores disturbed renal arginine synthesis after open aortic surgery: a randomized controlled clinical trial.

Postoperative renal failure is a common complication after open repair of an abdominal aortic aneurysm. The amino acid arginine is formed in the kidneys from its precursor citrulline, and citrulline is formed from glutamine in the intestines. Arginine enhances the function of the immune and cardiovascular systems, which is important for recovery after surgery. We hypothesized that renal arginine production is diminished after ischemia-reperfusion injury caused by clamping of the aorta during open abdominal aortic surgery and that parenteral glutamine supplementation might compensate for this impaired arginine synthesis. This open-label clinical trial randomized patients who underwent clamping of the aorta during open abdominal aortic surgery to receive a perioperative supplement of intravenous alanyl-glutamine (0.5 g·kg(-1)·day(-1); group A, n = 5) or no supplement (group B, n = 5). One day after surgery, stable isotopes and tracer methods were used to analyze the metabolism and conversion of glutamine, citrulline, and arginine. Whole body plasma flux of glutamine, citrulline, and arginine was significantly higher in group A than in group B (glutamine: 391 ± 34 vs. 258 ± 19 µmol·kg(-1)·h(-1), citrulline: 5.7 ± 0.4 vs. 2.8 ± 0.4 µmol·kg(-1)·h(-1), and arginine: 50 ± 4 vs. 26 ± 2 µmol·kg(-1)·h(-1), P < 0.01), as was the synthesis of citrulline from glutamine (4.8 ± 0.7 vs. 1.6 ± 0.3 µmol·kg(-1)·h(-1)), citrulline from arginine (2.3 ± 0.3 vs. 0.96 ± 0.1 µmol·kg(-1)·h(-1)), and arginine from glutamine (7.7 ± 0.4 vs. 2.8 ± 0.2 µmol·kg(-1)·h(-1)), respectively (P < 0.001 for all). In conclusion, the production of citrulline and arginine is severely reduced after clamping during aortic surgery. This study shows that an intravenous supplement of glutamine increases the production of citrulline and arginine and compensates for the inhibitory effect of ischemia-reperfusion injury.

Accurate mass screening of pharmaceuticals and fungicides in water by U-HPLC-Exactive Orbitrap MS.

The use of pharmaceuticals in livestock production is a potential source of surface water, groundwater and soil contamination. Possible impacts of antibiotics on the environment include toxicity and the emergence of antibiotic resistance. Monitoring programs are required to record the presence of these substances in the environment. A rapid, versatile and selective multi-method was developed and validated for screening 43 pharmaceutical and fungicides compounds, in surface and groundwater, in one single full-scan MS method, using benchtop U-HPLC-Exactive Orbitrap MS at 50,000 (FWHM) resolution. Detection was based on calculated exact masses and on retention time. Sample volume, pH conditions and solid-phase extraction (SPE) sample clean-up conditions were optimized. In the final method, 74 % of the compounds had recoveries higher than 80 %, 15 % of the compounds had recoveries between 60 % and 80 %, and 7 % of the compounds had recoveries between 40 % and 50 %. One of the compounds (itraconazole) had a recovery lower than 10 % and nystatin was not detected. The level of detection was 10 ng L(-1) for 61 % of the compounds, 50 ng L(-1) for 32 % and 100 ng L(-1) for 5%. In-house validation, based on EU guidelines, proves that the detection capability CCß is lower than 10 ng L(-1) (for ß error 5 %) for 37 % of the compounds, lower than 50 ng L(-1) for 35 % of the compounds and lower than 100 ng L(-1) for 14 % of compounds. This study demonstrates that the ultra-high resolution and reliable mass accuracy of Exactive Orbitrap MS permits the detection of pharmaceutical residues in a concentration range of 10-100 ng L(-1), applying a post target screening approach, in the multi-method conditions.

Ultrasonic or accelerated solvent extraction followed by U-HPLC-high mass accuracy MS for screening of pharmaceuticals and fungicides in soil and plant samples.

Different veterinary pharmaceuticals are used in agricultural livestock becoming a source of environment contamination. Furthermore, no regulation exists for the concentration limits of pharmaceuticals in soil or water. Monitoring programs for environment contamination with pharmaceuticals are needed, requiring new sensitive and selective screening methods. The present study focuses on developing a method for the simultaneous scanning of forty-two compounds (pharmaceuticals, azole biocides and fungicides) in soil and plant material samples. For extraction purposes the use of ultrasonic assisted and accelerated solvent extraction (ASE) were compared. The extract was purified and concentrated by applying a solid phase extraction step followed by ultra-high-performance-chromatographic separation and accurate-mass spectrometric detection using Exacte Orbitrap technology (FWHM 50,000). The effects of the different extraction solvents and conditions on the extraction efficiency were tested. Although both extraction approaches are applicable the optimal extraction efficiency was obtained by applying accelerated solvent extraction using solvent mixtures containing acetone for soil and methanol for plant samples. An ASE process has been validated for the determination of selected pharmaceuticals and fungicides in soil and in plant material. The recoveries from soil samples were >70% for more than 68% of the compounds. The levels of detection were ≤10 µg kg(-1) for 93% of the compounds tested. The recoveries from plant material were >70% for 64% of the compounds tested. The levels of detection were ≤10 µg kg(-1) for 66% of the compounds. The developed method was used to screen soil and plant material collected throughout the Netherlands and oxytetracycline residues were detected.

Influence of natural organic matter on the screening of pharmaceuticals in water by using liquid chromatography with full scan mass spectrometry.

The influence of natural organic matter on the screening of pharmaceuticals in water was determined by using high resolution liquid chromatography (HRLC) combined with full scan mass spectrometry (MS) techniques like time of flight (ToF) or Orbitrap MS. Water samples containing different amount of natural organic matter (NOM) and residues of a set of 11 pharmaceuticals were analyzed by using Exactive Orbitrap™ LC-MS. The samples were screened for residues of pharmaceuticals belonging to different classes like benzimidazoles, macrolides, penicillins, quinolones, sulfonamides, tetracyclines, tranquillizers, non-steroidal anti-inflammatory drugs (NSAIDs), anti-epileptics and lipid regulators. The method characteristics were established over a concentration range of 0.1-500 µg L(-1). The 11 pharmaceuticals were added to two effluent and two influent water samples. The NOM concentration within the samples ranged from 2 to 8 mg L(-1) of dissolved organic carbon. The HRLC-Exactive Orbitrap™ LC-MS system was set at a resolution of 50,000 (FWHM) and this selection was found sufficient for the detection of the list of pharmaceuticals. With this resolution setting, accurate mass measurements with errors below 2 ppm were found, despite of the NOM concentration of the different types of water samples. The linearities were acceptable with correlation coefficients greater than 0.95 for 30 of the 51 measured linearities. The limit of detection varies between 0.1 µg L(-1)and 100 µg L(-1). It was demonstrated that sensitivity could be affected by matrix constituents in both directions of signal reduction or enhancement. Finally it was concluded that with direct shoot method used (no sample pretreatment) all compounds, were detected but LODs depend on matrix-analyte-concentration combination. No direct relation was observed between NOM concentration and method characteristics. For accurate quantification the use of internal standards and/or sample clean-up is necessary. The direct shoot method is only applicable for qualitative screening purposes. The use of full scan MS makes it possible to search for unknown contaminants. With the use of adequate software and a database containing more than 50,000 entries a tool is available to search for unknowns.