Benchmarking in the process of donation after brain death: a methodology to identify best performer hospitals.

A benchmarking approach was developed in Spain to identify and spread critical success factors in the process of donation after brain death. This paper describes the methodology to identify the best performer hospitals in the period 2003-2007 with 106 hospitals throughout the country participating in the project. The process of donation after brain death was structured into three phases: referral of possible donors after brain death (DBD) to critical care units (CCUs) from outside units, management of possible DBDs within the CCUs and obtaining consent for organ donation. Indicators to assess performance in each phase were constructed and the factors influencing these indicators were studied to ensure that comparable groups of hospitals could be established. Availability of neurosurgery and CCU resources had a positive impact on the referral of possible DBDs to CCUs and those hospitals with fewer annual potential DBDs more frequently achieved 100% consent rates. Hospitals were grouped into each subprocess according to influencing factors. Hospitals with the best results were identified for each phase and hospital group. The subsequent study of their practices will lead to the identification of critical factors for success, which implemented in an adapted way should fortunately lead to increasing organ availability.

Orthogonal array optimization of a multiresidue method for cereal herbicides in soils.

Nearly 40 herbicides, commonly used for barley, were selected for analysis in soils of this crop. The primary objective was to develop a multiresidue method taking into account that herbicides belonged to different chemical families. Some preliminary experiments with different solvents in combination with water, acetic acid and ammonium hydroxide, were developed in order to design the predefined region covered by the orthogonal array design used for optimization. Final extracts were splitted in two aliquots, one of them was directly analyzed by gas chromatography-mass spectrometry (GC-MS), and the other one was derivatized before the acidic analyte analysis. Principal component analysis (PCA) was applied to the data generated in the preliminary experiments, in order to clarify the relationships among the different variables studied. According to the obtained results, the following variables were selected: solvent type and ratio, amount of acetic acid and extraction time. The statistical analysis revealed that all the factors were significant being the most important, the type and ratio of solvent for basic and neutral herbicides and the acetic acid percentage for acid herbicides. The final optimized method consisted of shaking previously wet soil samples for 30 min with 30 ml of acetone acidified with 1% acetic acid. Method validation was evaluated following the EU guidelines.

Comparison of an acetonitrile extraction/partitioning and "dispersive solid-phase extraction" method with classical multi-residue methods for the extraction of herbicide residues in barley samples.

An acetonitrile/partitioning extraction and "dispersive solid-phase extraction (SPE)" method that provides high quality results with a minimum number of steps and a low solvent and glassware consumption was published in 2003. This method, suitable for the analysis of multiple classes of pesticide residues in foods, has been given an acronymic name, QuEChERS, that reflects its major advantages (quick, easy, cheap, effective, rugged, safe). In this work, QuEChERS method, which was originally created for vegetable samples with a high amount of water, was modified to optimise the extraction of a wide range of herbicides in barley. Then, it was compared with known conventional multi-residue extraction procedures such as the Luke method, which was simplified and shortened by eliminating the Florisil clean-up (mini Luke) and the ethyl acetate extraction, which involves a subsequent clean-up by gel permeation chromatography (GPC) and which is the official extraction method used by some of European authorities. Finally, a simple acetone extraction was carried out to check the differences with the other three methods. Extracts were analysed by gas chromatography-time-of-flight mass spectrometry (GC-TOF/MS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). Mini Luke was significantly more effective for the extraction of non-polar and medium-polar compounds, but the best recoveries for polar compounds were achieved by QuEChERS and ethyl acetate methods. QuEChERS was the only method that provided an overall recovery value of 60-70% for non-, medium- and polar compounds, with some exceptions due to co-eluted matrix interferences. Clean-up by dispersive SPE was effective and did not differ so much with ethyl acetate extracts considering that QuEChERS clean-up step is much easier and less time-consuming. As a conclusion, it resulted to be the most universal extraction method by providing a well-defined phase separation without dilution and achieving acceptable recoveries in average including the extraction of the always difficult acidic herbicides. However, recoveries were not as good as required for validation purposes suggesting that residues are prone to strong matrix interactions in dry samples as barley and further method adaptation incrementing solvent strength, extraction time or more acidic or basic conditions is needed in order to achieve a complete extraction.

Study of different parameters affecting the derivatization of acidic herbicides with trimethylsulfonium hydroxide to make them suitable for gas chromatography analysis.

In this study, an orthogonal array design was applied to know the way different parameters affected the derivatization of some herbicides that are commonly applied in the soils. Herbicides formulated as esters have been reported to rapidly hydrolyse, in contact with soil, to their corresponding acids and phenols. What involves is that both forms need to be monitored. Acidic herbicides and phenols cannot be detected by gas chromatography (GC) due to their polarity and low volatility that cause peak asymmetry. Therefore, masking of these polar groups by eliminating the active hydrogen atom with derivatization to their corresponding esters/ethers is needed in order to yield products that possess enhanced volatility and improved GC properties. A lot of derivatization reagents have been proposed but trimethylsulfonium hydroxide (TMSH) was selected due to its easy and quantitative formation of methyl esters/ethers. It was observed that the addition of TMSH promoted not only esterification of acids/phenols but trans-esterification of the original non-hydrolyzed remaining esters to their corresponding methyl ones. As a result, methyl esters/ethers were the final product of both reactions. Different parameters were studied in the statistical design for both TMSH promoted reactions: type of solvent, pH, temperature and time of incubation. The amount of derivatization reagent was calculated to be high enough to ensure the complete derivatization of all compounds present in the sample. The reaction medium was shown as an important factor. The formation of some methyl esters/ethers decreased with increasing time and temperature because trans-esterification, being an equilibrium where the formation of smaller structures is promoted, was not enough shifted. However, the statistical analysis revealed that only the pH of the solution played an important role during the derivatization process. The presence of the anionic form of the acids appeared to be essential for derivatization, being diminished in strong acidic conditions. In addition, pre-heating was shown not to improve derivatization reaction, being easily carried on in the injector port of the GC system.

[Cholesterol, alpha-tocopherol, and retinoid concentrations in silicone oil used as a vitreous substitute]. / concentraciones de colesterol, alfa-tocoferol y retinoides en aceite de silicona tras su utilización como sustitutivo vítreo.

OBJECTIVE: To verify the existence of organic lipophylic compounds in silicone oil extracted from human eyes following its use for previous retinal detachment, and to determine the intraocular permanence time of these substances in the oil. METHODS: Concentrations of retinoic acid, retinol, retinal, cholesterol and alpha-tocopherol were detected by HPLC in 23 samples of silicone oil extracted from patients with complicated retinal detachments. The time interval between the time of injection of the silicone oil and the subsequent assessment varied from 3 to 50 months (the permanence time). RESULTS: All tested compounds were found in the samples, but these were most commonly cholesterol and less frequently alpha-tocopherol. There was an inverse relationship between retinoic acid concentration and age (p=0.023), and a direct relationship between cholesterol concentration and permanence time (p=0.0008) at least up to 20 months. CONCLUSIONS: These findings confirm that silicone oil is not an inert substance but is capable of extracting lipophylic compounds from the intraocular tissues. There is a clear linear elevation of cholesterol levels with increased intraocular permanence time. This finding could be used to further establish a safe permanence time for intraocular silicone oil used in ophthalmologic surgery. More studies with larger samples are warranted to evaluate this further.

Concentraciones de colesterol, alfa-tocoferol y retinoiodes en aceite de silicona tras su utilización como sustitutivo vítreo / Cholesterol, alpha-tocopherol, and retinoid concentrations in silicone oil used as a vitreous substitute

Objetivo: Determinar si existen concentraciones de compuestos lipofílicos de origen orgánico en muestras de aceite de silicona extraídas de ojos humanos y comprobar si existe alguna relación con el tiempo de permanencia intraocular del aceite.Métodos: Por cromatografía líquida de alta resolución (HPLC) se han determinado las concentraciones de ácido retinoico, retinol, retinal, colesterol y a-tocoferol en 23 muestras de aceite de silicona de 1.000 cs, extraídas de pacientes con desprendimientos complejos de retina con tiempos de permanencia intraocular variables (3 a 50 meses).Resultados: Se han encontrado concentraciones de todos los compuestos, sobre todo de colesterol, y en menor medida de alfa-tocoferol. Se ha observado una correlación inversa de la edad y las concentraciones de ácido retinoico (p=0,023). Y una correlación directa entre el tiempo de permanencia intraocular del aceite y los niveles de colesterol (p=0,0008) que se mantiene hasta los 20 meses.Conclusiones: Se confirma que el aceite de silicona no es una sustancia tan inerte ya que es capaz de disolver compuestos lipídicos procedentes de tejidos intraoculares. Existe una elevación linear de los niveles de colesterol que podría utilizarse como orientación para decidir cuándo extraer el aceite de silicona, aunque hacen falta estudios con series más grandes

Objective: To verify the existence of organic lipophylic compounds in silicone oil extracted from human eyes following its use for previous retinal detachment, and to determine the intraocular permanence time of these substances in the oil.Methods: Concentrations of retinoic acid, retinol, retinal, cholesterol and alpha-tocopherol were detected by HPLC in 23 samples of silicone oil extracted from patients with complicated retinal detachments. The time interval between the time of injection of the silicone oil and the subsequent assessment varied from 3 to 50 months (the permanence time).Results: All tested compounds were found in the samples, but these were most commonly cholesterol and less frequently alpha-tocopherol. There was an inverse relationship between retinoic acid concentration and age (p=0.023), and a direct relationship between cholesterol concentration and permanence time (p=0.0008) at least up to 20 months.Conclusions: These findings confirm that silicone oil is not an inert substance but is capable of extracting lipophylic compounds from the intraocular tissues. There is a clear linear elevation of cholesterol levels with increased intraocular permanence time. This finding could be used to further establish a safe permanence time for intraocular silicone oil used in ophthalmologic surgery. More studies with larger samples are warranted to evaluate this further

Clinical consequences of the use of highly purified silicone oil. Comparative study of highly and less purified silicone oil.

PURPOSE: To compare the ocular toxicity caused by the use of highly purified silicone oil to less purified silicone oil in humans. METHODS: Fifty-six eyes received 2,000 centistokes (cs) purified silicone oil (group 1) and 42 eyes received 2,000 cs fractionated (highly purified) silicone oil (group 2) after pars plana vitrectormy. Follow-up ranged from 6 to 48 months. RESULTS: Six months after injection, the following complications were found in groups 1 and 2, respectively: ocular hypotension (< 13 mmHg), 39.3% and 31%, sustained ocular hypertension (> 23 mmHg), 19.6% and 19%; acute hypertensive peaks (> 30 mmHg), 23.2% and 11.9%; corneal alterations, 19.6% and 14.3%; emulsification, 1.8% and 2.4%; silicone oil cloudiness, 28.6% and 0%; preretinal reproliferation, 14.3% and 4.8% and total or partial retinal reattachment, 78.6% and 90.5%. CONCLUSIONS: Highly purified silicone oil was better tolerated than the less purified oil and caused fewer complications. Poorly purified silicone oils should be avoided in clinical practice.

Determination of glutathione, cysteine and N-acetylcysteine in rabbit eye tissues using high-performance liquid chromatography and post-column derivatization with 5,5'-dithiobis(2-nitrobenzoic acid).

A high-performance liquid chromatographic method to determine glutathione, cysteine and N-acetylcysteine in rabbit retina, vitreous and lens has been developed. The thiols are separated using a 25 x 0.46-cm octadecylsilane column with 0.5 M phosphate buffer, pH 3, as mobile phase. The detection, at 412 nm, involves a post-column derivatization with 5,5-dithiobis(2-nitrobenzoic acid) in presence of cationic micelles of hexadecyltrimethylammonium bromide that enhances the sensitivity. The detection limits are 0.21, 0.92 and 0.61 mumol/g wet sample for glutathione, cysteine and N-acetylcysteine, respectively.

High-performance liquid chromatographic determination of vancomycin in rabbit serum, vitreous and aqueous humour after intravitreal injection of the drug.

A high-performance liquid chromatographic method for the determination of vancomycin in rabbit serum, vitreous and aqueous humour has been developed. No clean-up step was necessary for vitreous and aqueous humour samples. For serum samples liquid-liquid and solid-phase extraction were tested and the best results were achieved using C18 cartridges. The extracts were analyzed on a C18 reversed-phase column, using a mixture of 0.05 M phosphate buffer (pH 4) with 10% of acetonitrile as mobile phase. The detection was carried out at 198 nm, which allows higher sensitivity. The average quantitation limit obtained was 0.03 micrograms/ml. The method has been applied to the study of the residual quantities of vancomycin in serum and rabbit eyes after intravitreal administration of the drug in endophthalmitis treatment.

Determination of the concentrations of 5-fluorouracil and its metabolites in rabbit plasma and tissues by high-performance liquid chromatography.

The concentrations of 5-fluorouracil, 5-fluoro-5,6-dihydrouracil, 5-fluorouridine and 5-fluoro-2'-deoxyuridine in plasma, liver, kidney, lung and heart of rabbits were determined by high-performance liquid chromatography (HPLC) after drug administration by two different routes. HPLC was carried out by using a Spherisorb 5 ODS 2 column and 0.05 M phosphate buffer as the mobile phase with UV detection at 200 nm. The pH of the mobile phase, organic modifier content and column temperature were found to have a profound influence on the results, hence it was necessary to optimize a procedure for each matrix. A comparison of the efficiency of intravenous and peritoneal administration revealed that the latter provides higher drug concentrations in the liver and minimal contents in plasma and all other tissues studied.