Dispersive liquid-liquid microextraction for a rapid determination of glyoxal in alcoholic beverages

Publication date: 1 June 2017
Source:Talanta, Volume 168
Author(s): María Isabel Rodríguez-Cáceres, Mónica Palomino-Vasco, Nielene Mora-Diez, María Isabel Acedo-Valenzuela
Carbonyl compounds, like glyoxal, methylglyoxal, diacetyl or pentane-2,3-dione, among others, have been widely studied. Besides its endogenous origin, they are originated from foodstuffs and are related to sensorial characteristics in products such as wine and beer. Generally, for their determination, the analytes must be derivatised to adapt them for the detection system and this step takes long time. The main aim of this research was to develop a simultaneous derivatization and extraction method which takes place in only few minutes. 3,4-diaminopyridine, as derivatizing reagent, generate a fluorescent product. This reaction is selective for glyoxal. For this new dispersive liquid-liquid microextraction (DLLME) procedure combined with chromatographic determination of glyoxal, various parameters affecting the extraction were optimized and finally, a mixture of butan-1-ol as dispersant solvent and dichloromethane as extractant solvent were selected. Its chromatographic peak appears at 2.6min. Four Spanish wines and five Spanish beers have been analysed and the results showed that the levels of glyoxal are comprised between 2.8–9.5mgL⁻¹. The proposed DLLME method drastically reduces the reaction time from 2 or 3–20min improving the methods found in the literature. The glyoxal concentration found in the wines and beers analysed do not suppose any health risk.

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Low-voltage electrochemically stimulated stir membrane liquid-liquid microextraction as a novel technique for the determination of methadone

Publication date: 1 June 2017
Source:Talanta, Volume 168
Author(s): Katayoun Mahdavi Ara, Farhad Raofie
In the present work, for the first time, a new portable setup was designed, developed and presented for the extraction of methadone, as a basic drug model from biological fluid samples using a low-voltage electrically stimulated stir membrane liquid–liquid microextraction technique (LV-ESSM-LLME), followed by high-performance liquid chromatography with ultraviolet detection. This new approach combines the advantages of stir membrane liquid–liquid microextraction and electrokinetic migration in the same unit under soft electrochemical conditions in a portable device, allowing for the isolation and preconcentration of the target analyte in a simple and efficient manner under three-phase mode. To investigate the influence of external stirring and the application of electrical potential as the driving force, a comparative study of all variables involved in the extraction process was carried out using the low-voltage electromembrane extraction (LV-EME) and LV-ESSM-LLME methods. Under soft electrokinetic migration conditions, methadone was transported from an acidic sample solution (pH 4.0), through the NPOE immobilized in the pores of the porous polypropylene sheet membrane, and into 25µL of 10mmolL⁻¹ HCl acceptor solution with a stirring rate of 1000rpm and 700rpm after 15min and 20min for LV-ESSM-LLME and LV-EME, respectively. Under the optimized conditions, preconcentration factors in the range of 17–24 and 21.5–29 for LV-EME and LV-ESSM-LLME, respectively, were considered, and satisfactory repeatability (4.5<[RSD]<7.5) was obtained in different matrices. The obtained relative recoveries of the target analyte were in the range of 87–94% and 93–101% for LV-EME and LV-ESSM-LLME, respectively, which indicated the excellent capability of the developed methods to extract methadone from complex matrices.

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Waitlisted Candidates With Polycystic Liver Disease are More Likely to be Transplanted Than Those With Chronic Liver Failure.

Background: Polycystic liver disease (PCLD) is characterized by cystic replacement of the hepatic parenchyma, leading to hepatic dysfunction, portal hypertension, and hepatomegaly. Patients with liver dysfunction and/or symptomatic disease are eligible for liver transplantation. However, little is known about these patients' waitlist outcomes relative to others with chronic liver disease. Methods: We used OPTN/UNOS data from February 27, 2002 to December 31, 2015 to compare waitlist outcomes of adult patients with PCLD to those with chronic liver failure (CLF) and hepatocellular carcinoma (HCC). Results: The study cohort included 620 patients with PCLD, 18 240 patients with HCC, and 98 567 patients with CLF. Compared to CLF patients, PCLD patients had significantly lower bilirubin and INR at waitlisting, and less ascites and encephalopathy. However, they were significantly more likely to have severe chronic kidney disease. Moreover, patients with PCLD were more than 70% more likely to be transplanted compared to patients with CLF (OR: 1.72, 95% CI: 1.46-2.02) and had significantly longer posttransplant survival (p

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Incidence of and Risk Assessment for Adverse Cardiovascular Outcomes Following Liver Transplantation: A Systematic Review.

Background: Cardiovascular events represent a major source of morbidity and mortality following liver transplantation and will likely increase given the aging population and nonalcoholic fatty liver disease as a leading indication for transplant. The optimal cardiovascular risk stratification approach in this evolving patient population remains unclear. The aims of this systematic review are to: 1) refine the definition 2) characterize the incidence, and 3) identify risk factors for cardiovascular events post liver transplantation. Additionally, we evaluated performance characteristics of different cardiac testing modalities. Methods: MEDLINE via PubMed, EMBASE, Web of Science and Scopus were searched for studies published between 2002 -2016 (MELD era). Two authors independently reviewed articles to select eligible studies and performed data abstraction. Results: 29 studies representing 57,493 patients from 26 unique cohorts were included. Definitions of cardiovascular outcomes were highly inconsistent. Incidence rates were widely variable: 1-41% for outcomes 6 months. Multivariate analyses demonstrated that older age and history of cardiac disease were the most consistent predictors of cardiovascular events posttransplant (significant in 8/23 and 7/22, studies respectively). Predictive capacity of various cardiac imaging modalities was also discrepant. Conclusions: The true incidence of cardiovascular outcomes post liver transplant remains unknown in large part due to lack of consensus regarding outcome definition. Overall, poor data quality and gaps in knowledge limit the ability to clearly identify predictors of outcomes, but existing data supports a more aggressive risk stratification protocol for patients of advanced age and/or with preexisting cardiac disease. Copyright (C) 2017 Wolters Kluwer Health, Inc. All rights reserved.

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Long Term Outcomes in Patients Undergoing Liver Transplantation for Nonalcoholic Steatohepatitis Related Cirrhosis.

Background: Nonalcoholic steatohepatitis (NASH), a clinically aggressive variant of nonalcoholic fatty liver disease (NAFLD), is becoming an increasingly common indication for liver transplantation (LT); however, relatively little is known regardings its clinical course post-LT. The aim of the current study is to describe disease recurrence and clinical course after LT. Methods: All surviving patients transplanted for NASH at the authors' institution had transient elastography (TE) to evaluate hepatic steatosis and fibrosis. The charts of deceased patients were reviewed for liver biopsy to evaluate for disease recurrence. Finally, causes of mortality in these patients were evaluated. Results: Of the 103 patients who met criteria, 56 had TE while 34 had a liver biopsy. Steatosis was detected in 49(87.5%) of patients who had a TE and were defined to have recurrent NAFLD. Most patients had liver stiffness measurements (LSM) consistent with no fibrosis(42.9%) or F1-F2 fibrosis(30.4%). Advanced fibrosis was noted in 26.8% while 5.4% had cirrhosis but were clinically compensated. In patients with liver biopsy, 88.2% had recurrent NAFLD, while 41.2% had recurrent NASH. Bridging fibrosis was noted in 20.6% of patients but no patients had cirrhosis. Within the cohort, 32 patients died with the leading cause of mortality cancer (25%), infectious complications (25%), and CVD (21.9%). Only 9% of deaths were attributable to graft cirrhosis. Conclusion: Recurrent NAFLD is common post-LT occurring in nearly 88% of all patients, while nearly a quarter of patients were noted to have advanced fibrosis. Copyright (C) 2017 Wolters Kluwer Health, Inc. All rights reserved.

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Phase behavior of aqueous polyacrylic acid solutions using atomistic molecular dynamics simulations of model oligomers

Publication date: 7 April 2017
Source:Polymer, Volume 114
Author(s): Ratna S. Katiyar, Prateek K. Jha
We have performed fully atomistic molecular dynamics simulations of aqueous solutions of a weak, pH-responsive polyelectrolyte, polyacrylic acid (PAA). Model oligomers of PAA of different tacticities, molecular weights, degrees of deprotonation, and deprotonation patterns are simulated with water molecules. Deprotonation of PAA chains that occurs with an increase in pH results in an increase in Coulomb repulsion between chain segments on one hand, and a non-monotonic change in the hydrogen bonding between chain segments on the other hand. Consequently, at the single chain level, PAA chains are stretched at higher pH values, where the amount of stretching varies with chain tacticity. For the multiple chains case, PAA forms aggregates at higher concentrations, which are relatively denser and contain lesser water (solid-like) at lower pH than compared to higher pH (liquid-like). Such phase transitions of PAA aggregates with pH has possible implications in the design of pH-responsive polyelectrolytes for applications in drug delivery.

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Magnetic resonance imaging characteristics of granulomatous mastitis

Publication date: Available online 15 March 2017
Source:Clinical Imaging
Author(s): Amanda N. Chu, Stephen J. Seiler, Jody C. Hayes, Rachel Wooldridge, Jessica H. Porembka, Basak Dogan
Granulomatous mastitis (GM) is a benign chronic inflammatory condition of the breast. This study was performed to determine the utility of magnetic resonance imaging (MRI) in differentiating GM from malignancy. MRI findings in 12 women with clinical or histopathologically-proven GM were retrospectively reviewed. Non-mass enhancement on MRI was present in all 12 patients with clustered ring enhancement being the most common pattern (n=7, 58%). Architectural distortion (n=10, 83%), skin thickening (n=10, 83%) and focal skin enhancement (n=10, 83%) were also very common. MRI features of GM are often identical to features considered suspicious for malignancy on MRI.



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