| 76701. |
- Galle, J. C., et al.
(författare)
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Outcomes in patients with chronic kidney disease not on dialysis receiving extended dosing regimens of darbepoetin alfa: long-term results of the EXTEND observational cohort study
- 2016
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Ingår i: Nephrology Dialysis Transplantation. - : Oxford University Press (OUP). - 0931-0509 .- 1460-2385. ; 31:12, s. 2073-2085
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Tidskriftsartikel (refereegranskat)abstract
- Background. Extended dosing of the erythropoiesis-stimulating agent (ESA) darbepoetin alfa (DA) once biweekly or monthly reduces anaemia treatment burden. This observational study assessed outcomes and dosing patterns in patients with chronic kidney disease not on dialysis (CKD-NoD) commencing extended dosing of DA. Methods. Adult CKD-NoD patients starting extended dosing of DA in Europe or Australia in June 2006 or later were followed up until December 2012. Outcomes included haemoglobin (Hb) concentration, ESA dosing, mortality rates and receipt of dialysis and renal transplantation. Subgroup analyses were conducted for selected outcomes. Results. Of 6035 enrolled subjects, 5723 (94.8%) met analysis criteria; 1795 (29.7%) received dialysis and 238 (3.9%) underwent renal transplantation. Mean (standard deviation) Hb concentration at commencement of extended dosing was 11.0 (1.5) g/dL. Mean [95% confidence interval (CI)] Hb 12 months after commencement of extended dosing (primary outcome) was 11.6 g/dL (11.5, 11.6) overall and was similar across countries, with no differences between subjects previously treated with an ESA versus ESA-naive subjects, subjects with versus without prior renal transplant or diabetics versus non-diabetics. Weekly ESA dose gradually decreased following commencement of extended DA dosing and was similar across subgroups. The decrease in weekly DA dose was accompanied by an increase in the proportion of patients receiving iron therapy. Hb concentrations declined following changes in ESA labels and treatment guidelines. The mortality rate (95% CI) was 7.06 (6.68, 7.46) deaths per 100 years of follow-up. Subjects alive at study end had stable Hb concentrations in the preceding year, while those who died had lower and declining Hb concentrations in their last year. Conclusions. Long-term, extended dosing of DA maintained Hb concentrations in patients already treated with an ESA and corrected and maintained Hb in ESA-naive patients.
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| 76702. |
- Gallego, Pablo, et al.
(författare)
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The intestinal MUC2 mucin C-terminus is stabilized by an extra disulfide bond in comparison to von Willebrand factor and other gel-forming mucins
- 2023
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Ingår i: Nature communications. - 2041-1723. ; 14
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Tidskriftsartikel (refereegranskat)abstract
- The MUC2 mucin polymer is the main building unit of the intestinal mucus layers separating intestinal microbiota from the host epithelium. The MUC2 mucin is a large glycoprotein with a C-terminal domain similar to the MUC5AC and MUC5B mucins and the von Willebrand factor (VWF). A structural model of the C-terminal part of MUC2, MUC2-C, was generated by combining Cryo-electron microscopy, AlphaFold prediction, information of its glycosylation, and small angle X-ray scattering information. The globular VWD4 assembly in the N-terminal of MUC2-C is followed by 3.5 linear VWC domains that form an extended flexible structure before the C-terminal cystine-knot. All gel-forming mucins and VWF form tail-tail disulfide-bonded dimers in their C-terminal cystine-knot domain, but interestingly the MUC2 mucin has an extra stabilizing disulfide bond on the N-terminal side of the VWD4 domain, likely essential for a stable intestinal mucus barrier.
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| 76703. |
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| 76704. |
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| 76705. |
- Gallego-Urrea, Julian A., 1977, et al.
(författare)
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Coagulation and sedimentation of gold nanoparticles and illite in model natural waters: Influence of initial particle concentration
- 2016
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Ingår i: NanoImpact. - : Elsevier BV. - 2452-0748. ; 3-4, s. 67-74
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Tidskriftsartikel (refereegranskat)abstract
- Gold nanoparticles (AuNP) possess unique characteristics that render them adequate for applications and also to be used as a model NP to evaluate the fate and behavior at low NP concentrations due to the ease of detection by modern analytical techniques. Moreover, AuNP may result in some negative effects in the environment and there is a necessity to predict their aquatic environmental concentrations by parameterizing the underlying transport and transformation processes. This study investigated the coagulation and sedimentation of 30 nm citrate-coated AuNP under enviro-mimicking conditions, i.e. model natural freshwaters (MNW) covering the range of European water chemistries relevant for colloids and NP (major ions, pH and dissolved organic matter) and artificial seawater (ASW). Firstly, the coagulation rates of AuNP at mg/L concentrations were evaluated using time-resolved dynamic light scattering which showed a decreased rate upon addition of Suwannee river natural organic matter (SRNOM) at low ionic strength (IS) but remained relatively high at high IS. Contrastingly, AuNP approaching environmental realistic concentrations (80 μg/L) in quiescent microcosms showed slow decline rates in all MNW and ASW regardless of the presence of SRNOM, as measured by nanoparticle tracking analysis and elemental Au spectrometry. When illite was added as model natural colloid the rates of decline of AuNP remained low as well. This is owing to limited collisions at low particle number concentrations. The results show that besides IS, pH, NOM concentration and type and the intrinsic surface charge of the particles, the particle number concentration and size distribution of both AuNP and natural colloids determine the extent of the large-scale fate of NP in aquatic environments.
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| 76706. |
- Gallego-Urrea, Julian A., 1977, et al.
(författare)
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Determination of pH in estuarine and brackish waters: Pitzer parameters for Tris buffers and dissociation constants for m-cresol purple at 298.15K
- 2017
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Ingår i: Marine Chemistry. - : Elsevier BV. - 0304-4203. ; 195, s. 84-89
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Tidskriftsartikel (refereegranskat)abstract
- © 2017 Elsevier B.V. Measurements of pH in seawater are important to determine the natural and anthropogenic trends in the oceans. Spectrophotometry or glass electrode potentiometry measurements of pH require calibration with help of buffers. One common buffer solution is the Tris/Tris·H + couple, which should be well characterised both experimentally and theoretically for optimum accuracy. Chemical speciation modelling in the complex seawater medium is best addressed with an ion interaction approach, with Pitzer equations being the most widely used. The published Pitzer coefficients for Tris and Tris·H + in artificial seawater are based on isopiestic measurements, which necessarily give strong weight to the third virial coefficient C for the key interaction between Tris·H + and chloride. However, in low salinity waters it is the second virial coefficient B that is of greater importance. We have used Harned cell measurements of Tris solutions at ionic strengths up to 1molkg -1 to reassess the relevant Pitzer parameters, and have found improved agreement with experimental measurements in artificial seawater. We suggest that additional measurements should be undertaken to address the remaining differences between model calculations and experimental data in artificial seawater. We have used the revised Pitzer parameters to reassess the acid-base constant of the indicator m-cresol purple in low salinity waters.
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| 76707. |
- Gallego-Urrea, Julian A., 1977, et al.
(författare)
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Influence of different types of natural organic matter on titania nanoparticle stability: effects of counter ion concentration and pH
- 2014
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Ingår i: Environmental Science-Nano. - : Royal Society of Chemistry (RSC). - 2051-8153. ; 1:2, s. 181-189
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Tidskriftsartikel (refereegranskat)abstract
- The effects of biopolymeric (alginate) and refractory macromolecules (humic and fulvic acids) on the aggregation kinetics of anatase titanium dioxide (titania) nanoparticles were evaluated. The particles were synthesized using a wet-chemical method based on the hydrolysis of TiCl4. Stable suspensions of positively-charged titania were obtained at pH 2.5. One batch of this product was shifted above the point of zero charge to pH 12. These dispersions were mixed with three different types of well characterized environmental macromolecules: sodium alginate, fulvic acid and humic acid, and evaluated in terms of the stability. Changes in the particle size were measured using time-resolved dynamic light scattering (TR-DLS) at different concentrations of three electrolytes: NaCl, CaCl2 and Na2SO4, and at different solution pH values. Results were in agreement with DLVO calculations. The use of TR-DLS for determining aggregation rates is critically discussed.
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| 76708. |
- Gallego-Urrea, Julian A., 1977, et al.
(författare)
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Measurements of nanoparticle number concentrations and size distributions in contrasting aquatic environments using nanoparticle tracking analysis
- 2010
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Ingår i: Environmental Chemistry. - 1449-8979. ; 7, s. 67-81
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Tidskriftsartikel (refereegranskat)abstract
- A feasibility study of nanoparticle tracking analysis (NTA) for aquatic environmental samples is presented here. The method has certain virtues such as minimum perturbation of the samples, high sensitivity in terms of particle concentration, and provision of number-based size distributions for aquatic samples. NTA gave linear calibration curves in terms of number concentration and accurately reproduced size measurements of certified reference material nanoparticles. However, the accuracy of the size distributions obtained with this method exhibited a high dependence on set-up parameters and the concentrations were shown to be strongly correlated with the refractive index of the material under examination. Different detection cameras and different data acquisition modeswere compared and evaluated. Also, the effect of filtration of the samples was assessed. The size distributions for the contrasting environmental samples were fairly reasonable compared with other studies but an underestimation of small sizes was observed, which can be explained by a materialdependent lower detection limit in terms of size. The number concentrations obtained for the natural nanoparticles ranged from 0.5 to 20×108 particles mL−1 and correlated well with conventional turbidity measurements.
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| 76709. |
- Gallego-Urrea, Julian A., 1977, et al.
(författare)
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Multimethod 3D characterization of natural plate-like nanoparticles: shape effects on equivalent size measurements
- 2014
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Ingår i: Journal of nanoparticle research. - : Springer Science and Business Media LLC. - 1388-0764 .- 1572-896X. ; 16:5
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Tidskriftsartikel (refereegranskat)abstract
- The fundamental properties and processes that govern nanoparticle behavior in colloidal dispersions are critical to predict their performance in applications and also their environmental and health implications. Illite is a platy clay mineral that is present in large amounts in aquatic environments and can be used as a model natural particle for environmental risk assessment. However, the high-aspect ratio of illite makes conventional analysis, usually assuming a spherical size, insufficient for the assessment of shape-dependent properties. In the current paper, a multimethod characterization of a suspension of illite particles was done using atomic force microscopy, scanning electron microscopy, dynamic light scattering (DLS), nanoparticle tracking analysis, differential centrifugal sedimentation, and centrifugal- field flow fractionation coupled to multiangle light scattering and DLS. The relation between the different measurands was investigated, and the effect of the shape on the equivalent particle size was reported. While some of the used techniques are capable of assessing the aspect ratio of illite, the results confirm the need for multiple techniques and analysis of different types of measurands especially for high-aspect-ratio particles.
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| 76710. |
- Gallego-Urrea, Julian A., 1977
(författare)
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On the exposure assessment of engineered nanoparticles in aquatic environments
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The socio-economic benefits anticipated with the use and production of nanomaterial and nanoparticles in consumer products are linked to the fulfillment of the requirement for sustainability during the whole material life cycle. Engineered nanoparticles (ENP) can be of environmental concern, both due to the possible hazardous effects but also due to the differences in properties compared to regular chemicals, e.g. elevated surface area per mass of nanoparticle, the possibility for enhanced mobility and trespassing biological membranes and other emerging novel properties at the nanoscale. There is a scientific consensus that nanoparticles, nanomaterials and their transformation products have a high probability to be released in the environment. ENP in the aquatic environment present a very dynamic behavior that has to be understood in order to perform a physicochemical-based risk assessment that elucidates their transformation and transport leading to the possibility to predict environmental concentrations and exposure. Therefore, there is a need for adequate theoretical and experimental platforms that can be used for supporting the adequate assessment of fate processes of ENP in the environment. The main results achieved in the thesis were reflected in: 1) identification of theoretical platforms that can provide solutions for the evaluation of fate processes of ENP in aquatic environments 2) improvement in the application of a novel particle tracking method for characterizing natural nanoparticles and ENP in different matrices; 3) identification of the effects of well-characterized NOM and counterion valence on the aggregation rates of TiO2 nanoparticles 4) developing a geographically distributed water classification for Europe based on river water chemistry, 5) use the geographical water classification to evaluate the aggregation and sedimentation of Au NP in in-situ quiescent-water microcosms. The physicochemical characteristics of the receiving water were found to be very influential on the fate of the ENP tested. The ionic concentration, presence of divalent counter ions (specifically calcium), the type of NOM and mass-ratio between NOM and the particles are among the most important parameters. NP coating, surface charge, material properties and shape will also play very important roles. NP number concentrations determine the degree of transport and transformation due to the different dynamic processes in the environment.
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