Effectiveness of emergency surgery for five common acute conditions: an instrumental variable analysis of a national routine database.

The effectiveness of emergency surgery vs. non-emergency surgery strategies for emergency admissions with acute appendicitis, gallstone disease, diverticular disease, abdominal wall hernia or intestinal obstruction is unknown. Data on emergency admissions for adult patients from 2010 to 2019 at 175 acute National Health Service hospitals in England were extracted from the Hospital Episode Statistics database. Cohort sizes were: 268,144 (appendicitis); 240,977 (gallstone disease); 138,869 (diverticular disease); 106,432 (hernia); and 133,073 (intestinal obstruction). The primary outcome was number of days alive and out of hospital at 90 days. The effectiveness of emergency surgery vs. non-emergency surgery strategies was estimated using an instrumental variable design and is reported for the cohort and pre-specified sub-groups (age, sex, number of comorbidities and frailty level). Average days alive and out of hospital at 90 days for all five cohorts were similar, with the following mean differences (95%CI) for emergency surgery minus non-emergency surgery after adjusting for confounding: -0.73 days (-2.10-0.64) for appendicitis; 0.60 (-0.10-1.30) for gallstone disease; -2.66 (-15.7-10.4) for diverticular disease; -0.07 (-2.40-2.25) for hernia; and 3.32 (-3.13-9.76) for intestinal obstruction. For patients with 'severe frailty', mean differences (95%CI) in days alive and out of hospital for emergency surgery were lower than for non-emergency surgery strategies: -21.0 (-27.4 to -14.6) for appendicitis; -5.72 (-11.3 to -0.2) for gallstone disease, -38.9 (-63.3 to -14.6) for diverticular disease; -19.5 (-26.6 to -12.3) for hernia; and - 34.5 (-46.7 to -22.4) for intestinal obstruction. For patients without frailty, the mean differences (95%CI) in days alive and out of hospital were: -0.18 (-1.56-1.20) for appendicitis; 0.93 (0.48-1.39) for gallstone disease; 5.35 (-2.56-13.28) for diverticular disease; 2.26 (0.37-4.15) for hernia; and 18.2 (14.8-22.47) for intestinal obstruction. Emergency surgery and non-emergency surgery strategies led to similar average days alive and out of hospital at 90 days for five acute conditions. The comparative effectiveness of emergency surgery and non-emergency surgery strategies for these conditions may be modified by patient factors.

Computer-Generated R.E.N.A.L. Nephrometry Scores Yield Comparable Predictive Results to Those of Human-Expert Scores in Predicting Oncologic and Perioperative Outcomes.

PURPOSE: We sought to automate R.E.N.A.L. (for radius, exophytic/endophytic, nearness of tumor to collecting system, anterior/posterior, location relative to polar line) nephrometry scoring of preoperative computerized tomography scans and create an artificial intelligence-generated score (AI-score). Subsequently, we aimed to evaluate its ability to predict meaningful oncologic and perioperative outcomes as compared to expert human-generated nephrometry scores (H-scores). MATERIALS AND METHODS: A total of 300 patients with preoperative computerized tomography were identified from a cohort of 544 consecutive patients undergoing surgical extirpation for suspected renal cancer at a single institution. A deep neural network approach was used to automatically segment kidneys and tumors, and geometric algorithms were developed to estimate components of R.E.N.A.L. nephrometry score. Tumors were independently scored by medical personnel blinded to AI-scores. AI- and H-score agreement was assessed using Lin's concordance correlation and their predictive abilities for both oncologic and perioperative outcomes were assessed using areas under the curve. RESULTS: Median age was 60 years (IQE 51-68), and 40% were female. Median tumor size was 4.2 cm and 91.3% had malignant tumors, including 27%, 37% and 24% with high stage, grade and necrosis, respectively. There was significant agreement between H-scores and AI-scores (Lin's ⍴=0.59). Both AI- and H-scores similarly predicted meaningful oncologic outcomes (p <0.001) including presence of malignancy, necrosis, and high-grade and -stage disease (p <0.003). They also predicted surgical approach (p <0.004) and specific perioperative outcomes (p <0.05). CONCLUSIONS: Fully automated AI-generated R.E.N.A.L. scores are comparable to human-generated R.E.N.A.L. scores and predict a wide variety of meaningful patient-centered outcomes. This unambiguous artificial intelligence-based scoring is intended to facilitate wider adoption of the R.E.N.A.L. score.

The Southern Ocean Exchange: porous boundaries between humpback whale breeding populations in southern polar waters.

Humpback whales (Megaptera novaeangliae) are a cosmopolitan species and perform long annual migrations between low-latitude breeding areas and high-latitude feeding areas. Their breeding populations appear to be spatially and genetically segregated due to long-term, maternally inherited fidelity to natal breeding areas. In the Southern Hemisphere, some humpback whale breeding populations mix in Southern Ocean waters in summer, but very little movement between Pacific and Atlantic waters has been identified to date, suggesting these waters constituted an oceanic boundary between genetically distinct populations. Here, we present new evidence of summer co-occurrence in the West Antarctic Peninsula feeding area of two recovering humpback whale breeding populations from the Atlantic (Brazil) and Pacific (Central and South America). As humpback whale populations recover, observations like this point to the need to revise our perceptions of boundaries between stocks, particularly on high latitude feeding grounds. We suggest that this "Southern Ocean Exchange" may become more frequent as populations recover from commercial whaling and climate change modifies environmental dynamics and humpback whale prey availability.

The Effect of the Hypertrophy Virus (MdSGHV) on the Ultrastructure of the Salivary Glands of Musca domestica (Diptera: Muscidae).

The salivary glands of insects play a key role in the replication cycle and vectoring of viral pathogens. Consequently, Musca domestica (L.) (Diptera: Muscidae) and the Salivary Gland Hypertrophy Virus (MdSGHV) serve as a model to study insect vectoring of viruses. A better understanding of the structural changes of the salivary glands by the virus will help obtain a better picture of the pathological impact the virus has on adult flies. The salivary glands are a primary route for viruses to enter a new host. As such, studying the viral effect on the salivary glands is particularly important and can provide insights for the development of strategies to control the transmission of vector-borne diseases, such as dengue, malaria, Zika, and chikungunya virus. Using scanning and transmission electron microscopic techniques, researchers have shown the effects of infection by MdSGHV on the salivary glands; however, the exact location where the infection was found is unclear. For this reason, this study did a close examination of the effects of the hypertrophy virus on the salivary glands to locate the specific sites of infection. Here, we report that hypertrophy is present mainly in the secretory region, while other regions appeared unaffected. Moreover, there is a disruption of the cuticular, chitinous lining that separates the secretory cells from the lumen of the internal duct, and the disturbance of this lining makes it possible for the virus to enter the lumen. Thus, we report that the chitinous lining acts as an exit barrier of the salivary gland.

Theoretical and experimental study of the LR-115 detector response in a non-commercial radon monitor.

B.trαcks, a simulation program for SSNTD's sensitivity, has been developed to study the response of LR-115 (cellulose nitrate) and CR-39 (poly allyl glycol carbonate) nuclear track detectors. Detectors are located inside detector holders and are used for radon measurements. The program incorporates a variety of special features gathered together to achieve good agreement between theoretical approach and experimental results. The input parameters to study the detector response are radon exposure, geometry and dimensions of a detector holder (it can be cylindrical, conical or semi-spherical), entrance type for radon gas, detector type, and V function (four different functions were selected from literature). The output results are detector response and radon progeny distribution onto internal chamber walls. In this article, the response of the LR-115, which is placed inside a non-commercial-conductive radon monitor based on diffusion chambers called G2, was theoretically and experimentally studied. The common Monte Carlo simulation procedure and an alternative approach that replicates how monitors are exposed to different radon exposures were used as theoretical approaches. Experimental methodology was conducted in a radon test chamber from Italy (MI.AM s.r.l.). Comparison results of both theoretical and experimental methodology are presented and discussed. One of the major results, among others, shows that the monitor material (conductive or non-conductive) does not influence the LR-115 response.

Puntos críticos en la evaluación y tratamiento de octogenarios con colecistolitiasis / Critical points in the evaluation and treatment of octogenarians with colecistolitiasis

Resumen Introducción: Existe una tendencia global al envejecimiento y con ello un aumento de patologías asociadas. En Chile la prevalencia de la colelitiasis o colecistolitiasis aumenta con la edad, siendo la cole-cistectomía una de las cirugías más frecuentes. Existen escasos estudios latinoamericanos referentes a la realidad de la población octogenaria expuesta a este problema. Objetivo: Estudiar la morbimortalidad posoperatoria en pacientes octogenarios operados de colecistectomía. Definir la precisión de distintas herramientas diagnósticas preoperatorias, estudiar variables operatorias y precisar costos hospitalarios. Materiales y Método: Estudio observacional retrospectivo de la ficha clínica electrónica del Hospital Clínico de la Universidad de Chile, entre enero de 2012 y mayo de 2017. Se incluyeron pacientes con edad igual o mayor a 80 años, en quienes se realizó una colecistectomía electiva o de urgencia por patología benigna. Resultados: Se incluyeron 145 pacientes, 51,7% fueron mujeres, el promedio de edad fue de 84,1 años y un 74,5% presentaba comorbilidades. El 62,1% de los casos ingresó por urgencia. 26,2% de toda la muestra presentó coledocolitiasis. La colecistectomía fue laparoscópica en 73,8% de la muestra global, la tasa de conversión fue de 14,5% en población de urgencia y 1,8% en población electiva (p = 0,009). La población operada totalmente por vía laparoscópica con coledocolitiasis fue resuelta en un 95,2% a través de Rendez-vous, con una tasa de éxito del 100%. La tasa de complicaciones fue de 17,9% siendo en su mayoría médicas, la mortalidad quirúrgica fue de 2,1%, siendo todos casos de urgencia. El costo promedio de atención en salud hospitalaria fue de $5.888.104 pesos chilenos (U$9.000). Conclusión: El paciente octogenario con colecistolitiasis representa un desafío quirúrgico, dado un mayor número de comorbilidades, un cuadro clínico más agresivo y una elevada tasa de coledocolitiasis. Es aconsejable valorar el abordaje mínimamente invasivo y realizar una colangiografía intraoperatoria de rutina.

Introduction: There is a global tendency to aging and associated pathologies. In Chile, the prevalence of cholecystolithiasis increases with age, cholecystectomy is one of the most frequent surgeries in the contry. There are few latinamerican studies regarding the reality of the elderly exposed to this problem. Objective: Study postoperative morbimortality in octogenarian patients undergoing cholecystectomy. Define the accuracy of different preoperative diagnostic tools, study operative variables and specify hospital costs. Materials and Method: Retrospective observational study of the Clinical Hospital of the University of Chile, between January 2012 and May 2017. Patients with age equal to or greater than 80 years were included, in whom an elective or emergency cholecystectomy was performed for benign pathology. Results: A total of 145 patients were included, 51.7% were women, the average age was 84.1 years, and 74.5% had comorbidities. The admission was throw the emergency department in 62.1% of the cases. Choledocholithiasis was diagnosed in 26.2% of the entire sample. Cholecystectomy was fully laparoscopic in 73.8% of the overall sample, the conversion rate was 14.5% in the emergency population and 1.8% in the elective population (p = 0.009). The population operated fully laparoscopically, that had choledocholithiasis, was resolved in 95.2% through Rendezvous technique, with a 100% clearance rate of common bile duct. The complication rate was 17.9%, most being medical. The surgical mortality was 2.1%, all cases operated from emergency. The average cost of hospital health care was $5,888,104.3 Chilean pesos (U$9.000). Conclusion: The octogenarian patient with cholecystolithiasis represents a surgical challenge, given a greater number of comorbidities, a more aggressive clinical setting and a high rate of choledocolithiasis. It is advisable to assess the minimally invasive approach and perform routine intraoperative cholangiography. In the postoperative period, the cardiopulmonary status and the infectious complications of the surgical site should be monitored closely.

Reflexiones sobre la donación en asistolia controlada (donantes tipo III de Maastricht) / Reflections upon donation after controlled cardiac death (Maastricht type III donors)

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Inexistence of permafrost at the top of the Veleta peak (Sierra Nevada, Spain).

A 114.5m deep drilling was carried out in August 2000 in the bedrock of the Veleta peak, at 3380m in the massif of Sierra Nevada, Southern Spain. The objective of this work is to analyse temperatures at the first 60m depth of this drilling from September 2002 to August 2013 based on 11 UTL-1 thermal loggers located at different depths, together with air temperatures at the summit of the Veleta peak. Permanent negative temperatures have not been detected in the borehole, which shows evidence of the absence of widespread permafrost conditions nowadays in the highest lands of this massif. Bedrock temperatures oscillated between 3.2°C at 0.6m depth and 2°C at 20m below the surface. The largest temperature ranges were recorded on the most external sensors until 1.2m depth, where values reached 22.3°C. Seasonal temperature variations were significant until 10m depth. The thickness of the seasonal frozen layer was highly variable (0.6-2m) and dependent on annual climate conditions. The mean air temperature at the Veleta peak increased by 0.12°C during the study period. Bedrock temperatures followed diverging trends: a drop of 0.3-0.4°C down to 0.6m depth, a decrease of up to 0.7°C between 4 and 10m, thermal stability at 20m and a rise of 0.2°C that occurred in 2009 at the deepest sensor at 60m. The calculation of the thermal wave damping in the subsoil of the Veleta peak has allowed for quantifying the thermal diffusivity of the rock as (7.05±0.03)10(-7)m(2)/s, which means that the external climate signal arrives with an 8.5-year lag to the sensor at 60m deep. This allows to deduce a trend change in the climate of the area, moving from warmer conditions towards a trend of cooling from 2006 to 2007.

Functional outcomes and quality of life after chemoradiotherapy: baseline and 3 and 6 months post-treatment.

Concomitant chemoradiotherapy provides organ preservation for those patients with head and neck cancer. We report the results of a prospective study that examined functional outcomes and quality of life (QOL) after chemoradiotherapy over the first 6 months post-treatment (tx). Twenty-nine patients with head and neck cancer were treated with chemoradiotherapy. All were seen baseline and 3 and 6 months post-tx. Assessments included the performance status scale (PSS), Karnofsky performance status scale, tongue strength, jaw opening, and saliva weight. QOL was patient-rated using the eating assessment tool (EAT-10), MD Anderson dysphagia inventory, speech handicap index (SHI), and the EORTC H&N35 scale. Repeated-measures ANOVAs were used, with significance at p < 0.05. PSS scores were significantly different across time points. Tongue strength, jaw range of motion (ROM), and saliva weight were significantly lower at 3 and 6 months than at baseline. QOL was significantly worse after tx, although it improved by 6 months as rated with the EAT-10 and the SHI scores were significantly worse at 3 and 6 months. EORTC domains of swallowing, senses, speech, dry mouth, and sticky saliva were significantly worse at 3 and 6 months. Concomitant chemoradiotherapy for treatment of head and neck tumors can result in impaired performance outcomes and QOL over the first 6 months post-tx. However, performance status, tongue strength, jaw ROM, and eating QOL were only mildly impaired by 6 months post-tx. Saliva production and speech QOL remained significantly impaired at 6 months post-treatment. Current studies are examining outcomes at 12 and 24 months post-treatment to better predict outcomes over time in this population.

The Polycomb group (PcG) protein EZH2 supports the survival of PAX3-FOXO1 alveolar rhabdomyosarcoma by repressing FBXO32 (Atrogin1/MAFbx).

The Polycomb group (PcG) proteins regulate stem cell differentiation via the repression of gene transcription, and their deregulation has been widely implicated in cancer development. The PcG protein Enhancer of Zeste Homolog 2 (EZH2) works as a catalytic subunit of the Polycomb Repressive Complex 2 (PRC2) by methylating lysine 27 on histone H3 (H3K27me3), a hallmark of PRC2-mediated gene repression. In skeletal muscle progenitors, EZH2 prevents an unscheduled differentiation by repressing muscle-specific gene expression and is downregulated during the course of differentiation. In rhabdomyosarcoma (RMS), a pediatric soft-tissue sarcoma thought to arise from myogenic precursors, EZH2 is abnormally expressed and its downregulation in vitro leads to muscle-like differentiation of RMS cells of the embryonal variant. However, the role of EZH2 in the clinically aggressive subgroup of alveolar RMS, characterized by the expression of PAX3-FOXO1 oncoprotein, remains unknown. We show here that EZH2 depletion in these cells leads to programmed cell death. Transcriptional derepression of F-box protein 32 (FBXO32) (Atrogin1/MAFbx), a gene associated with muscle homeostasis, was evidenced in PAX3-FOXO1 RMS cells silenced for EZH2. This phenomenon was associated with reduced EZH2 occupancy and H3K27me3 levels at the FBXO32 promoter. Simultaneous knockdown of FBXO32 and EZH2 in PAX3-FOXO1 RMS cells impaired the pro-apoptotic response, whereas the overexpression of FBXO32 facilitated programmed cell death in EZH2-depleted cells. Pharmacological inhibition of EZH2 by either 3-Deazaneplanocin A or a catalytic EZH2 inhibitor mirrored the phenotypic and molecular effects of EZH2 knockdown in vitro and prevented tumor growth in vivo. Collectively, these results indicate that EZH2 is a key factor in the proliferation and survival of PAX3-FOXO1 alveolar RMS cells working, at least in part, by repressing FBXO32. They also suggest that the reducing activity of EZH2 could represent a novel adjuvant strategy to eradicate high-risk PAX3-FOXO1 alveolar RMS.

[Colorectal surgery in patients over 65 years of age]. / Cirugía colorrectal en pacientes mayores de 65 años.

BACKGROUND: There is a limited functional reserve in patients over 65 years of age which is conducive to more frequent postoperative complications. Disease extension at the time of diagnosis (clinical stage) and complete tumor resection are two independent risk factors that have a direct influence on survival. AIMS: To describe the factors that influence morbidity and mortality in patients over 65 years of age after colorectal surgery. MATERIAL AND METHODS: A retrospective, observational, descriptive study was carried out within the time frame of January 2004 and December 2009 on 105 colon cancer patients after colorectal surgery. They were divided into two groups, one under 65 years of age and the other over 65 years of age, in order to compare preoperative comorbidity, as well as morbidity and mortality 30 days after surgery. RESULTS: Of the 105 patient total (53,3%), 56 were ≤ 65 years of age. There were complications in 42,8% of the patients, and those of early and less severe presentation were the most frequent; late complications were more frequent in patients ≤ 65 vs > 65 years of age (16,0% vs 10,2%). Overweight (BMI > 25 kg/m(2)) was observed in 35,0% of the study population. Patients > 65 years of age had fewer comorbidities. The most common causes of reintervention were anastomosis dehiscence and postoperative hemorrhage. Mortality in the group was 6,6% and sepsis was the most frequent cause of death. CONCLUSIONS: Colorectal surgery in patients over 65 years of age has an acceptable complication frequency and a low mortality rate. Our results suggest that patients older than 65 years of age be treated with the same prospects for cure as younger patients.

Relación entre el gradiente alveolo-arterial de oxígeno y la PaO2/FiO2 introduciendo la PEEP en el modelo / Relationship between the alveolar-arterial oxygen gradientand PaO2/FiO2-introducing peep into the model

Objetivo: Valorar si el gradiente alveolo-arterial de oxígeno (Grad[A-a]O2) ayuda a confirmar la influencia de la PEEP en la PaFi (PaO2/FiO2). Diseño: Estudio observacional; usamos una regresión lineal para realizar un estudio multivariable y mejorar la fórmula de la PaFi teniendo en cuenta la PEEP. Ámbito: Hospital terciario. Pacientes: Todos los pacientes de cuidados intensivos, con o sin daño pulmonar. Variables de interés principal: Registramos los antecedentes personales, juicio clínico, datos durante ingreso en UCI, puntuaciones de severidad en el primer día y durante evolución; dos variables calculadas: PaFi and Grad(A-a)O2. Resultados: Un total de 956 patientes incluidos; 63,9% hombres; edad mediana 68 años. Primer día, 31,8% no tienen ventilación mecánica (VM), 13,1% tienen VM no invasiva y 55,1% VM invasiva. PaFi: 32,9% 0-200, 32,2% 201-300, y 34,8% >300. PEEP: 0-5 69,8%, 6-10 27,5% y >10 2,6%. Observamos una correlación (Pearson) entre el Grad(A-a)O2 y la PaFi de -0,84 (p<0,001). Realizamos una regresión múltiple (variable dependiente: Grad(A-a)O2Grad[A-a]O2); variables incluidas en el modelo: PaFi, PEEP, APACHE IV y SOFA; coeficiente de determinación (R2) de 0,62 sin PEEP y 0,72 con PEEP. Cambiamos la fórmula de la PaFi, denominándola PaFip (PaFi más PEEP): Ln (PaFi/[PEEP+12]). El índice de correlación entre PaFip y Grad(A-a)O2: -0,9 (p<0,001). Realizamos una regresión lineal (variable dependiente: Grad[A-a]O2) y utilizamos PaFip en vez de la PaFi. Solo la PaFi permanece en el modelo, y es discretamente complementada por APACHE IV; R2 0,8. Conclusiones: Añadiendo la PEEP a la PaFi, creamos una variable (PaFip) que mejora el modelo, demostrando mayor capacidad de bondad de ajuste (AU)

Objectives To determine whether the alveolar-arterial oxygen gradient (Grad[A-a]O2) helps confirm the influence of PEEP on PaFi (PaO2/FiO2). Design: Observational study; we used linear regression to perform a multivariate study to improve the PaFi formula by taking PEEP into account. Setting: Tertiary hospital. Patients: We included all patients who were admitted to the intensive care unit, regardless of pulmonary damage. Variables: We recorded personal history, clinical judgment, intensive care data, severity scores on the first day and progression. Two calculated variables: PaFi and Grad(A-a)O2. Results: A total of 956 patients were included: 63.9% men; median age 68 years. On the first day, 31.8% did not have mechanical ventilation (MV), 13.1% had non-invasive MV and 55.1% had invasive MV. PaFi values: 32.9% 0-200, 32.2% 201-300, and 34.8% >300. PEEP values: 0-5 69.8%, 6-10 27.5% and >10 2.6%. We observed a correlation (Pearson) between Grad(A-a)O2 and PaFi of -0.84 (p<0.001). On performing multiple regression (dependent variable: Grad[A-a]O2), the following variables were included in the model: PaFi, PEEP, APACHE IV and SOFA; coefficient of determination (R2) of 0.62 without PEEP and 0.72 with PEEP. We changed the PaFi formula, referring to it as PaFip (PaFi plus PEEP): Ln (PaFi/[PEEP+12]). Correlation index between PaFip and Grad(A-a)O2: -0.9 (p<0.001). We performed linear regression (dependent variable: Grad[A-a]O2) and used PaFip instead of PaFi. Only PaFi remained in the model, and was discretely complemented by APACHE IV; R2=0.8. Conclusions: By adding PEEP to the PaFi model (PaFip), we clearly improve the latter, as reflected by a better goodness of fit (AU)

[Relationship between the alveolar-arterial oxygen gradient and PaO2/FiO2-introducing PEEP into the model]. / Relación entre el gradiente alveolo-arterial de oxígeno y la PaO2/FiO2 introduciendo la PEEP en el modelo.

OBJECTIVES: To determine whether the alveolar-arterial oxygen gradient (Grad[A-a]O2) helps confirm the influence of PEEP on PaFi (PaO2/FiO2). DESIGN: Observational study; we used linear regression to perform a multivariate study to improve the PaFi formula by taking PEEP into account. SETTING: Tertiary hospital. PATIENTS: We included all patients who were admitted to the intensive care unit, regardless of pulmonary damage. VARIABLES: We recorded personal history, clinical judgment, intensive care data, severity scores on the first day and progression. Two calculated variables: PaFi and Grad(A-a)O2. RESULTS: A total of 956 patients were included: 63.9% men; median age 68 years. On the first day, 31.8% did not have mechanical ventilation (MV), 13.1% had non-invasive MV and 55.1% had invasive MV. PaFi values: 32.9% 0-200, 32.2% 201-300, and 34.8% >300. PEEP values: 0-5 69.8%, 6-10 27.5% and >10 2.6%. We observed a correlation (Pearson) between Grad(A-a)O2 and PaFi of -0.84 (p<0.001). On performing multiple regression (dependent variable: Grad[A-a]O2), the following variables were included in the model: PaFi, PEEP, APACHE IV and SOFA; coefficient of determination (R²) of 0.62 without PEEP and 0.72 with PEEP. We changed the PaFi formula, referring to it as PaFip (PaFi plus PEEP): Ln (PaFi/[PEEP+12]). Correlation index between PaFip and Grad(A-a)O2: -0.9 (p<0.001). We performed linear regression (dependent variable: Grad[A-a]O2) and used PaFip instead of PaFi. Only PaFi remained in the model, and was discretely complemented by APACHE IV; R²=0.8. CONCLUSIONS: By adding PEEP to the PaFi model (PaFip), we clearly improve the latter, as reflected by a better goodness of fit.

Pressurized liquid extraction with in-cell clean-up followed by gas chromatography-tandem mass spectrometry for the selective determination of parabens and triclosan in indoor dust.

A sample preparation method based on the use of pressurized liquid extraction is proposed for the determination of four alkyl parabens and triclosan in indoor dust. Extraction of analytes and removal of interfering species were achieved in the same step, by placing an appropriate sorbent in the extraction cell and by choosing a right combination of washing and elution solvents. Compounds, as silylated derivatives, were determined by gas chromatography in combination with tandem mass spectrometry (GC-MS/MS). Factors affecting the yield and selectivity of the sample preparation procedure were carefully evaluated. Under final conditions, dried samples (0.5 g of dust and 1g of sodium sulphate) were dispersed with 3g of Florisil and loaded into an 11 mL stainless-steel extraction cell containing 1g of the same material as clean-up sorbent. Non-polar species were removed with n-hexane under mild conditions (40 degrees C, 3.4 MPa) and then analytes were extracted with ethyl acetate. The best compromise extraction conditions were 103 degrees C, 13.8 MPa and 3 static extraction cycles of 1 min. The proposed method provided recoveries from 76 to 98%, relative standard deviations under 11% (operating under reproducibility conditions) and quantification limits from 1 to 4 ng/g. The analysis of dust samples from private houses and office buildings confirmed the ubiquitous presence of target bacteriocides in these environments.