| 1. |
- Adoberg, Annika, et al.
(författare)
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Treatment with Paracetamol Can Interfere with the Intradialytic Optical Estimation in Spent Dialysate of Uric Acid but Not of Indoxyl Sulfate
- 2022
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Ingår i: Toxins. - : MDPI. - 2072-6651. ; 14:9
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Tidskriftsartikel (refereegranskat)abstract
- Optical online methods are used to monitor the haemodialysis treatment efficiency of end stage kidney disease (ESKD) patients. The aim of this study was to analyse the effect of the administration of UV-absorbing drugs, such as paracetamol (Par), on the accuracy of optical monitoring the removal of uremic toxins uric acid (UA) and indoxyl sulfate (IS) during standard haemodialysis (HD) and haemodiafiltration (HDF) treatments. Nine patients received Par in daily dosages 1-4 g for 30 sessions. For 137 sessions, in 36 patients the total daily dosage of UV-absorbing drugs was less than 500 mg, and for 6 sessions 3 patients received additional UV-absorbing drugs. Par administration slightly affected the accuracy of optically assessed removal of UA expressed as bias between optically and laboratory-assessed reduction ratios (RR) during HD but not HDF employing UV absorbance of spent dialysate (p < 0.05) at 295 nm wavelength with the strongest correlation between the concentration of UA and absorbance. Corresponding removal of IS based on fluorescence at Ex280/Em400 nm during HD and HDF was not affected. Administration of UV-absorbing drugs may in some settings influence the accuracy of optical assessments in spent dialysate of the removal of uremic solutes during haemodialysis treatment of ESKD patients.
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| 4. |
- Dezelah, Charles L., et al.
(författare)
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A low valent metalorganic precursor for the growth of tungsten nitride thin films by atomic layer deposition
- 2007
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Ingår i: Journal of Materials Chemistry. - : Royal Society of Chemistry (RSC). - 0959-9428 .- 1364-5501. ; 17:11, s. 1109-1116
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Tidskriftsartikel (refereegranskat)abstract
- The atomic layer deposition growth of tungsten nitride films was demonstrated using the precursors W-2(NMe2)(6) and ammonia with substrate temperatures between 150 and 250 degrees C. At 180 degrees C, surface saturative growth was achieved with W-2(NMe2)(6) pulse lengths of >= 2.0 s. The growth rates were between 0.74 and 0.81 angstrom cycle(-1) at substrate temperatures between 180 and 210 degrees C. Growth rates of 0.57 and 0.96 angstrom cycle(-1) were observed at 150 and 220 degrees C, respectively. In a series of films deposited at 180 degrees C, the film thicknesses varied linearly with the number of deposition cycles. Films grown at 180 and 210 degrees C exhibited resistivity values between 810 and 4600 mu Omega cm. Time-of-flight elastic recoil detection analysis on tungsten nitride films containing a protective AlN overlayer demonstrated slightly nitrogen-rich films relative to W2N, with compositions of W1.0N0.82C0.13O0.26H0.33 at 150 degrees C, W1.0N0.74C0.20O0.33H0.28 at 180 degrees C, and W1.0N0.82C0.33O0.18H0.23 at 210 degrees C. In the absence of an AlN overlayer, the oxygen and hydrogen levels were much higher, suggesting that the films degrade in the presence of ambient atmosphere. The as-deposited films were amorphous. Amorphous films containing a protective AlN overlayer were annealed to 600 - 800 degrees C under a nitrogen atmosphere. X-Ray diffraction patterns suggested that crystallization does not occur at or below 800 degrees C. Similar annealing of films that did not contain the AlN overlayer afforded X-ray diffraction patterns that were consistent with orthorhombic WO3. Atomic force microscopy showed root-mean-square surface roughnesses of 0.9, 0.8, and 0.7 nm for films deposited at 150, 180, and 210 degrees C, respectively.
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| 5. |
- Fridolin, Ivo, et al.
(författare)
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A New Optical Method for Measuring Creatinine Concentration Removed During Dialysis
- 2010
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Ingår i: XII Mediterranean Conference on Medical and Biological Engineering and Computing 2010 IFMBE Proceedings, 2010. - Berlin, Heidelberg : Springer. - 9783642130380 - 9783642130397 ; , s. 379-382
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Konferensbidrag (refereegranskat)abstract
- The aim of this study was to compare creatinine (Cr) concentration measurements removed during dialysis by two optical algorithms based on single wavelength and multiwavelength UV-absorbance. Ten uremic patients, three females and seven males, mean age 62.6 ± 18.6 years, on chronic thrice-weekly hemodialysis were included in the study. Double-beam spectrophotometer (Shimatsu UV-2401 PC, Japan) was used for the determination of UV-absorbance in the collected spent dialysate samples. Two optical algorithms were developed to calculate Cr concentration removed during dialysis from measured UVabsorbance: (i) an algorithm utilizing only a single wavelength, revealing Cr concentration Cr_sw; (ii) an algorithm utilizing several wavelengths (multiwavelength algorithm), revealing Cr concentration Cr_mw. The mean value of Cr estimated at the laboratory was 107 ± 46,7 micromol/l, while UV-absorbance as Cr_sw (242 nm) was 107 ± 42.7 micromol/l, and 107 ± 44.7 micromol/l as Cr_mw. The mean concentrations were not significantly different (P = 0.99). The systematic errors, using Cr_lab as a reference, were -2.7% for Cr_sw and -1.7% for Cr_mw, and random errors were 17.3% and 13.6% for Cr_sw and Cr_mw, respectively. The systematic error was not significantly different for two optical algorithms (P = 0.25). The random error decreased significantly (P < 0.05) using Cr_mw algorithm compared to the Cr_sw model. In summary, the creatinine concentration removed during dialysis can be estimated with UV-absorbance technique.
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| 8. |
- Holmar, Jana, et al.
(författare)
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Optical method for cardiovascular risk marker uric acid removal assessment during dialysis
- 2012
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Ingår i: Scientific World Journal. - : Hindawi Limited. - 1537-744X. ; 2012, s. 8-
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to estimate the concentration of uric acid (UA) optically by using the original and processed ultraviolet (UV) absorbance spectra of spent dialysate. Also, the effect of using several wavelengths (multi-wavelength algorithms) for estimation was examined. This paper gives an overview of seven studies carried out in Linköping, Sweden, and Tallinn, Estonia. A total of 60 patients were monitored over their 188 dialysis treatment procedures. Dialysate samples were taken and analysed by means of UA concentration in a chemical laboratory and with a double-beam spectrophotometer. The measured UV absorbance spectra were processed. Three models for the original and three for the first derivate of UV absorbance were created; concentrations of UA from the different methods were finally compared in terms of mean values and SD. The mean concentration (micromol/L) of UA was 49.7 ± 23.0 measured in the chemical laboratory, and 48.9 ± 22.4 calculated with the best estimate among all models. The concentrations were not significantly different (P ≥ 0.17). It was found that using a multi-wavelength and processed signal approach leads to more accurate results, and therefore these approaches should be used in future.
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| 10. |
- Jerotskaja, Jana, et al.
(författare)
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A multicentre study of an enhanced optical method for measuring concentration of uric acid removed during dialysis.
- 2009
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Ingår i: Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2009. EMBC 2009. - 9781424432967 ; , s. 1477-1480
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Konferensbidrag (refereegranskat)abstract
- The aim of this study was to compare concentration measurements of uric acid (UA) removed during dialysis by two algorithms based on UV-absorbance and the 1st derivate of UV absorbance. Ten uremic patients from Tallinn and ten from Linköping, during 30+40 haemodialysis treatments, were followed at the Departments of Dialysis and Nephrology at North-Estonian Medical Centre and at Linköping University Hospital. The dialysate samples were taken and analyzed by means of UA concentration at the chemical laboratory and with a double-beam spectrophotometer. UV absorbance and derivate of UV absorbance was transformed into UA concentration in the spent dialysate using the regression models from the calibration set of material, noted as UV-absorbance (UV_A) and the 1st derivate of UV absorbance (UV_D) method. These models were tested on validation set of material and concentrations of UA from the two methods were compared regarding mean values and SD. Mean concentration of UA were 52.7 +/- 25.0 micromol/l measured at the chemical laboratory (UA_Lab), 54.9 +/- 23.8 micromol/l determined by UV_A and 52.9 +/- 23.0 micromol/l determined by UV_D. The results of mean concentrations were not significantly different (p >/= 0.54). The systematic errors were -7.8 % and -3.3% and random errors were 15.8 % and 10.4 % using UV_A and UV_D respectively. The systematic and random errors were significantly different (p < 0.05) indicating that the new algorithm enables more accurate UA estimation.
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