Over the last years, liquid-phase microextraction (LPME) in its different application modes (single drop microextraction, dispersive liquid–liquid microextraction and hollow fiber-LPME) has been ...increasingly applied for the extraction of both inorganic and organic analytes from different matrices. Its advantages over conventional extraction procedures (simplicity, effectiveness, rapidity and low consumption of organic solvents) has also attracted its application in the complex food analysis field, in which it has clearly provided good and challenging results. A comprehensive review dealing with those articles published since its introduction till the end of March 2011 is presented, offering also a critical vision of the analytical potential of LPME for the analysis of foods.
Carbon nanotubes: Solid-phase extraction Ravelo-Pérez, Lidia M.; Herrera-Herrera, Antonio V.; Hernández-Borges, Javier ...
Journal of Chromatography A,
04/2010, Letnik:
1217, Številka:
16
Journal Article
Recenzirano
Since the first report in 1991, carbon nanotubes (CNTs) have shown great possibilities for a wide variety of processes and applications, which include their use as electrodes, sensors (gas, ...enzymatic, etc.), nanoprobes, electronic materials, field emitters, etc. The combination of structures, dimensions and topologies has provided physical and chemical attractive properties that are unparalleled by most known materials. Their applications have also reached the Analytical Chemistry field in which CNTs are being used as matrices in matrix assisted laser desorption ionization, stationary phases in either gas chromatography, high performance liquid chromatography or capillary electrochromatography, also as pseudostationary phases in capillary electrophoresis, etc. as well as new solid-phase extraction (SPE) materials. Concerning this last application the number of works has considerably increased in the last five years. This review article pretends to focus on the most important features and different applications of SPE using CNTs (including matrix solid-phase dispersion and solid-phase microextraction) covering articles published since their introduction up to now (September 2009).
Purpose
To evaluate the optical and aberrometric outcomes of an enhanced monofocal intraocular lens (ISOPure) compared with those of a standard monofocal lens (MicroPure) having the same platform and ...material.
Methods
A prospective, comparative and randomised clinical study. A total of 28 eyes of 28 patients were randomly assigned to either group. Monocular visual acuity (VA) was measured at distance and intermediate under photopic and mesopic conditions. Aberrometry was analysed for 3.0‐, 4.0‐, 4.5‐ and 5.0 mm pupils. The contrast sensitivity defocus curve was measured for 3.0‐ and 4.5‐mm pupils, while the modulation transfer function (MTF) and Strehl ratio (SR) were assessed with a double‐pass system. All measurements were performed monocularly 3 months after surgery.
Results
No significant differences were found for distance VA. Under photopic conditions, intermediate VA was better with the ISOPure lens, while no significant differences were found between the lenses under mesopic conditions. Internal and total aberrations were higher for the ISOPure lens. No significant differences were found for corneal aberrations. Additionally, both the contrast sensitivity defocus curve and optical quality showed similar behaviour for each lens, with the MTF cut‐off frequency exceeding 30 c/deg in both cases.
Conclusion
The isofocal ISOPure lens enhanced intermediate VA without affecting distance VA under photopic conditions. Moreover, there were no significant differences in visual quality between the ISOPure and MicroPure lenses, despite the former exhibiting higher internal and total aberrations than the monofocal model.
Multi-walled carbon nanotubes (MWCNTs) have been used for the first time as solid-phase extraction (SPE) sorbents for the extraction of eight organophosphorus pesticides (i.e. ethoprophos, diazinon, ...chlorpyriphos-methyl, fenitrothion, malathion, chlorpyriphos, fenamiphos and buprofezin) from different commercial fruit juices (i.e. apple, grape, orange and pineapple). The developed method, which involves SPE and direct gas chromatography with nitrogen phosphorus detection analysis, is very fast, simple and cheap: only 1:1 dilution with Milli-Q water and pH adjustment to 6.0 of 10
mL of juice is necessary prior to a quick MWCNTs-SPE procedure that used only 40
mg of stationary phase (MWCNTs of 10–15
nm o.d., 2–6
nm i.d. and 0.1–10
μm length). Mean recovery values were above 73% for all the pesticides and fruit juices (between 77 and 101% for apple juice, 75 and 103% for grape juice, 73 and 103% for orange juice and 73 and 93% for pineapple juice) with a relative standard deviation (RSD) lower than 8.5% in all cases. Matrix matched calibration was carried out for each sample matrix since statistical differences between the calibration curves constructed is pure solvent and in the reconstructed juice extracts were found. Limits of detection ranged between 1.85 and 7.32
μg/L (which also represents LODs between 1.85 and 7.34
μg/kg) well below the European Union maximum residue limits for the raw fruits. The proposed method, which is demonstrated to be quick, cheap, accurate and highly selective, was also applied to the analysis of this group of pesticides in several commercial juices in which none of the selected pesticides were found.
How cells communicate to initiate a regenerative response after damage has captivated scientists during the last few decades. It is known that one of the main signals emanating from injured cells is ...the Reactive Oxygen Species (ROS), which propagate to the surrounding tissue to trigger the replacement of the missing cells. However, the link between ROS production and the activation of regenerative signaling pathways is not yet fully understood. We describe here the non-autonomous ROS sensing mechanism by which living cells launch their regenerative program. To this aim, we used Drosophila imaginal discs as a model system due to its well-characterized regenerative ability after injury or cell death. We genetically-induced cell death and found that the Apoptosis signal-regulating kinase 1 (Ask1) is essential for regenerative growth. Ask1 senses ROS both in dying and living cells, but its activation is selectively attenuated in living cells by Akt1, the core kinase component of the insulin/insulin-like growth factor pathway. Akt1 phosphorylates Ask1 in a secondary site outside the kinase domain, which attenuates its activity. This modulation of Ask1 activity results in moderate levels of JNK signaling in the living tissue, as well as in activation of p38 signaling, both pathways required to turn on the regenerative response. Our findings demonstrate a non-autonomous activation of a ROS sensing mechanism by Ask1 and Akt1 to replace the missing tissue after damage. Collectively, these results provide the basis for understanding the molecular mechanism of communication between dying and living cells that triggers regeneration.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract Background Many health care systems claim to incorporate the cost-effectiveness criterion in their investment decisions. Information on the system’s willingness to pay per effectiveness ...unit, normally measured as quality-adjusted life-years (QALYs), however, is not available in most countries. This is partly because of the controversy that remains around the use of a cost-effectiveness threshold, about what the threshold ought to represent, and about the appropriate methodology to arrive at a threshold value. Objectives The aim of this article was to identify and critically appraise the conceptual perspectives and methodologies used to date to estimate the cost-effectiveness threshold. Methods We provided an in-depth discussion of different conceptual views and undertook a systematic review of empirical analyses. Identified studies were categorized into the two main conceptual perspectives that argue that the threshold should reflect 1) the value that society places on a QALY and 2) the opportunity cost of investment to the system given budget constraints. Results These studies showed different underpinning assumptions, strengths, and limitations, which are highlighted and discussed. Furthermore, this review allowed us to compare the cost-effectiveness threshold estimates derived from different types of studies. We found that thresholds based on society’s valuation of a QALY are generally larger than thresholds resulting from estimating the opportunity cost to the health care system. Conclusions This implies that some interventions with positive social net benefits, as informed by individuals’ preferences, might not be an appropriate use of resources under fixed budget constraints.
In this work, a new method for the determination of eleven quinolone antibiotics (moxifloxacin, lomefloxacin, danofloxacin, ciprofloxacin, levofloxacin, marbofloxacin, enrofloxacin, difloxacin, ...pefloxacin, oxolinic acid and flumequine) in different water samples using dispersive solid-phase extraction (dSPE) and capillary zone electrophoresis with diode-array detection was developed. Oxidized multi-walled carbon nanotubes (o-MWCNTs) were used for the first time as stationary phases for the off-line preconcentration by dSPE of the antibiotics. A 65
mM phosphate buffer at pH 8.5 was found adequate for analyte separation while large volume sample stacking with polarity switching of the analytes dissolved in water containing 10% (v/v) of acetonitrile was carried out in order to improve the sensitivity. dSPE parameters, such as sample volume and pH, o-MWCNT amount, volume and type of eluent in dSPE were optimized. Application of the developed method to the analysis of spiked Milli-Q, mineral, tap, and wastewater samples resulted in good recoveries values ranging from 62.3 to 116% with relative standard deviation values lower than 7.7% in all cases. Limits of detection were in the range of 28–94
ng/L. The proposed method is very fast, simple, repeatable, accurate and highly selective.
Rationale, aims and objectives
Self‐monitoring of blood glucose (SMBG) is recommended to monitor glycaemic levels. The recent development of real‐time continuous glucose monitoring (RT‐CGM) enables ...continuous display of glucose concentration alerting patients in the event of relevant glucose fluctuations, potentially avoiding hypoglycaemic events and reducing long‐term complications related to glycosylated haemoglobin (HbA1c) levels. This paper aims to evaluate the cost‐effectiveness of RT‐CGM compared to SMBG in patients with type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM) which should support decision‐making on public funding of RT‐CGM in Spain.
Methods
We performed a systematic review and meta‐analyses on the effectiveness of RT‐CGM in the reduction of HbA1c levels and severe hypoglycaemic events. A cost‐effectiveness analysis was conducted using a Markov model which simulates the costs and health outcomes of individuals treated under these alternatives for a lifetime horizon from the perspective of the Spanish Health Service. The effectiveness measure was quality‐adjusted life years (QALYs). We ran extensive sensitivity analyses, including a probabilistic sensitivity analysis.
Results
Real‐time continuous glucose monitoring provides a significant reduction of HbA1c for T1DM (13 studies; weighted mean difference (WMD) = −0.23%, 95% CI: −0.35, −0.11) and T2DM (5 studies; WMD = −0.48%, 95% CI: −0.79, −0.17). There were no statistically significant differences in the rate of severe hypoglycaemic events in T1DM (9 studies; OR = 1.16, 95% CI: 0.78, 1.72) or T2DM (no severe hypoglycaemic events were reported in any study). In the base case analysis, RT‐CGM led to higher QALYs and health care costs with an estimated incremental cost‐effectiveness ratio of €2 554 723 and €180 553 per QALY for T1DM and T2DM patients respectively. Sensitivity analyses revealed that the study results were robust.
Conclusions
Real‐time continuous glucose monitoring is not a cost‐effective technology when compared to SMBG in Spain.
Purpose To study the psychometric properties, including reliability, validity and responsiveness, of the Spanish EQ-5D-5L questionnaire for patients with hip or knee osteoarthritis (OA). Methods We ...included 758 patients with hip or knee OA who completed the EQ-5D-5L and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) at baseline, of whom 644 also did 6 months later. The EQ-5D-5L contains five questions from which a utility index is derived. The WOMAC covers three dimensions: pain, stiffness and physical function. Floor and ceiling effects were calculated. Reliability was assessed using Cronbach's alpha. Convergent validity was tested using the Spearman correlation coefficient between EQ-5D-5L and WOMAC. We examined known-groups validity by comparing the EQ-5D-5L between subgroups defined by WOMAC scores using ANOVA or the Kruskal-Wallis test. Effect sizes were calculated to assess responsiveness, and minimal clinically important difference (MCID) was estimated. Results The EQ-5D-5L showed minimal floor and ceiling effects (< 3%). Cronbach's alpha was 0.86. The EQ-5D-5L index was strongly correlated with WOMAC pain and function scores (-0.688 and -0.782). Patients with higher WOMAC scores had significantly (p < 0.0001) lower EQ-5D-5L index. The 20.19% had hip or knee replacement during the follow-up. Effect sizes were small among non-surgical patients, but >0.80 among "improved" surgical patients, being the MCID for improvement 0.32 points. Conclusions The results support the reliability, validity and responsiveness of the EQ-5D-5L, overcoming the limitations of the EQ-5D-3L in these patients. Therefore, the EQ-5D-5L could be very useful as an outcome measure, at least in patients with hip or knee OA.
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