| 1. |
- Abdel-Khalik, Jonas, et al.
(författare)
-
Incorporation of (14)C-cholesterol in human adrenal corticocarcinoma H295R cell line and online-radiodetection of produced (14)C-steroid hormone metabolites
- 2017
-
Ingår i: Journal of Pharmaceutical and Biomedical Analysis. - 0731-7085 .- 1873-264X. ; 145, s. 569-575
-
Tidskriftsartikel (refereegranskat)abstract
- This study demonstrates the addition of (14)C-cholesterol to the human cell line H295R will in-situ form radiolabeled steroid hormones allowing for new mechanistic and metabolic insights. The aim of the present study was to in-situ radiolabel steroid hormones from cell line-incorporated (14)C-cholesterol using the OECD guideline 456, H295R steroidogenesis in-vitro assay. Radiodetection of the steroid metabolites of the steroidogenic pathway allows for an improved understanding of the various enzymatic mechanisms involved without necessarily being dependent on quantification. Generated radiolabeled steroids were analyzed using HPLC hyphenated with a Flow Scintillation Analyzer (FSA). H295R cells were incubated with radiolabeled cholesterol and cell media were collected and prepared by solid phase extraction and analyzed with HPLC-FSA. For successful radiolabeling of the steroids in the steroidogenesis of H295R cells, radioactive cholesterol may potentially only need to be added just before the cells are incubated for 72h in well plates. Based on the obtained HPLC-FSA chromatograms, and confirmation of the observations by studies in the literature, a qualitative time profile for the production of steroid hormones was estimated. Multiple radiolabeled steroid hormones were identified by means of analytical standards and UV (ultraviolet) co-chromatography, though the elucidation of multiple metabolites remains unresolved. Although online radiodetection proved to suffer from suboptimal sensitivity, the concept of radiolabeling the steroidogenesis in H295R cells with (14)C-cholesterol and detecting the radiolabeled steroid hormones online was proved and may assist in further toxicological studies.
|
|
| 2. |
- Abdel-Khalik, Jonas, et al.
(författare)
-
Incorporation of (14)C-cholesterol in human adrenal corticocarcinoma H295R cell line and online-radiodetection of produced (14)C-steroid hormone metabolites
- 2017
-
Ingår i: Journal of Pharmaceutical and Biomedical Analysis. - : Elsevier. - 0731-7085 .- 1873-264X. ; 145, s. 569-575
-
Tidskriftsartikel (refereegranskat)abstract
- This study demonstrates the addition of (14)C-cholesterol to the human cell line H295R will in-situ form radiolabeled steroid hormones allowing for new mechanistic and metabolic insights. The aim of the present study was to in-situ radiolabel steroid hormones from cell line-incorporated (14)C-cholesterol using the OECD guideline 456, H295R steroidogenesis in-vitro assay. Radiodetection of the steroid metabolites of the steroidogenic pathway allows for an improved understanding of the various enzymatic mechanisms involved without necessarily being dependent on quantification. Generated radiolabeled steroids were analyzed using HPLC hyphenated with a Flow Scintillation Analyzer (FSA). H295R cells were incubated with radiolabeled cholesterol and cell media were collected and prepared by solid phase extraction and analyzed with HPLC-FSA. For successful radiolabeling of the steroids in the steroidogenesis of H295R cells, radioactive cholesterol may potentially only need to be added just before the cells are incubated for 72h in well plates. Based on the obtained HPLC-FSA chromatograms, and confirmation of the observations by studies in the literature, a qualitative time profile for the production of steroid hormones was estimated. Multiple radiolabeled steroid hormones were identified by means of analytical standards and UV (ultraviolet) co-chromatography, though the elucidation of multiple metabolites remains unresolved. Although online radiodetection proved to suffer from suboptimal sensitivity, the concept of radiolabeling the steroidogenesis in H295R cells with (14)C-cholesterol and detecting the radiolabeled steroid hormones online was proved and may assist in further toxicological studies.
|
|
| 3. |
- Abdel–Khalik, Jonas, et al.
(författare)
-
Development of a solid phase extraction method for the simultaneous determination of steroid hormones in H295R cell line using liquid chromatography–tandem mass spectrometry
- 2013
-
Ingår i: Journal of chromatography. B. - 1570-0232 .- 1873-376X. ; 935:September, s. 61-69
-
Tidskriftsartikel (refereegranskat)abstract
- The H295R in vitro cell line produces the majority of the steroidogenesis, for which reason it is commonly used as a screening tool for endocrine disrupting chemicals. Simultaneous determination of the precursor cholesterol and key steroid hormones could give a broad insight into the mechanistic disruption of the steroidogenesis. Steroid hormones have primarily been extracted from H295R incubation medium by means of liquid-liquid extraction (LLE) and the obtained recoveries and matrix effects have typically not been stated or assessed. In the present study a solid-phase extraction (SPE) method was developed and validated for the simultaneous extraction of cholesterol and five key steroid hormones pregnenolone, 17-hydroxyprogesterone, testosterone, cortisol and aldosterone from H295R incubation medium, and finally detected by LC-MS/MS. Cholesterol was recovered at a level of 55.7%, while steroid hormone recoveries ranged from 98.2 to 109.4%. Matrix effects varied between -0.6% and 62.8%. Intra-day precision was deemed acceptable, but the inter-day precision for pregnenolone and aldosterone exceeded the precision limit of 15% RSD. Although LLE has been the most frequently used extraction method in H295R studies, however, our investigation has shown that SPE may relatively easily extract and recover steroid hormones, potentially replacing LLE.
|
|
| 4. |
- Abdel–Khalik, Jonas, et al.
(författare)
-
Development of a solid phase extraction method for the simultaneous determination of steroid hormones in H295R cell line using liquid chromatography–tandem mass spectrometry
- 2013
-
Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232. ; 935:September, s. 61-69
-
Tidskriftsartikel (refereegranskat)abstract
- The H295R in vitro cell line produces the majority of the steroidogenesis, for which reason it is commonly used as a screening tool for endocrine disrupting chemicals. Simultaneous determination of the precursor cholesterol and key steroid hormones could give a broad insight into the mechanistic disruption of the steroidogenesis. Steroid hormones have primarily been extracted from H295R incubation medium by means of liquid-liquid extraction (LLE) and the obtained recoveries and matrix effects have typically not been stated or assessed. In the present study a solid-phase extraction (SPE) method was developed and validated for the simultaneous extraction of cholesterol and five key steroid hormones pregnenolone, 17-hydroxyprogesterone, testosterone, cortisol and aldosterone from H295R incubation medium, and finally detected by LC-MS/MS. Cholesterol was recovered at a level of 55.7%, while steroid hormone recoveries ranged from 98.2 to 109.4%. Matrix effects varied between -0.6% and 62.8%. Intra-day precision was deemed acceptable, but the inter-day precision for pregnenolone and aldosterone exceeded the precision limit of 15% RSD. Although LLE has been the most frequently used extraction method in H295R studies, however, our investigation has shown that SPE may relatively easily extract and recover steroid hormones, potentially replacing LLE.
|
|
| 5. |
- Abdel–Khalik, Jonas, et al.
(författare)
-
Simultaneous determination of endogenous steroid hormones in human and animal plasma and serum by liquid or gas chromatography coupled to tandem mass spectrometry
- 2013
-
Ingår i: Journal of chromatography. B. - 1570-0232 .- 1873-376X. ; 928:June, s. 59-77
-
Tidskriftsartikel (refereegranskat)abstract
- Analytical methodologies based on liquid or gas chromatography coupled to tandem mass spectrometry for the simultaneous determination of two or more endogenous steroid hormones in human and animal plasma and serum has received increased attention the last few years. Especially in the clinical setting steroid profiling is of major importance in disease diagnostics. This paper discusses recent findings in such multi-steroid hormone procedures published from 2001 to 2012. The aim was to elucidate possible relationships between chosen analytical technique and the obtained analyte sensitivity for endogenous steroid hormones. By evaluating the success, at which the currently applied techniques have been utilized, more general knowledge on the field is provided. Furthermore the evaluation provides directions in which future studies may be interesting to conduct.
|
|
| 6. |
- Abdel–Khalik, Jonas, et al.
(författare)
-
Simultaneous determination of endogenous steroid hormones in human and animal plasma and serum by liquid or gas chromatography coupled to tandem mass spectrometry
- 2013
-
Ingår i: Journal of chromatography. B. - : Elsevier BV. - 1570-0232. ; 928:June, s. 59-77
-
Tidskriftsartikel (refereegranskat)abstract
- Analytical methodologies based on liquid or gas chromatography coupled to tandem mass spectrometry for the simultaneous determination of two or more endogenous steroid hormones in human and animal plasma and serum has received increased attention the last few years. Especially in the clinical setting steroid profiling is of major importance in disease diagnostics. This paper discusses recent findings in such multi-steroid hormone procedures published from 2001 to 2012. The aim was to elucidate possible relationships between chosen analytical technique and the obtained analyte sensitivity for endogenous steroid hormones. By evaluating the success, at which the currently applied techniques have been utilized, more general knowledge on the field is provided. Furthermore the evaluation provides directions in which future studies may be interesting to conduct.
|
|
| 7. |
- Ahlström, Lars-Henric, et al.
(författare)
-
Determination of banned azo dyes in consumer goods
- 2005
-
Ingår i: Trac. Trends in Analytical Chemistry. - : Elsevier BV. - 0165-9936. ; 24:1, s. 49-56
-
Tidskriftsartikel (refereegranskat)abstract
- Azo dyes, extensively used for coloring a variety of consumer goods, such as leather, clothes, food, and toys, can under certain conditions be reduced to form confirmed or suspected carcinogenic aromatic amines. This article gives an overview of the state of development of analytical procedures for the determination of such azo dyes, which are banned by the European Commission. (C) 2004 Elsevier Ltd. All rights reserved.
|
|
| 8. |
- Ahlström, Lars-Henric, et al.
(författare)
-
Optimization of an analytical procedure for the determination of banned azo dyes in leather
- 2005
-
Ingår i: Analytical and Bioanalytical Chemistry. - : Springer Science and Business Media LLC. - 1618-2642 .- 1618-2650. ; 382:5, s. 1320-1327
-
Tidskriftsartikel (refereegranskat)abstract
- The possibility of improving an existing method, based on supercritical-fluid extraction (SFE) and microwave-assisted extraction (MAE), for the determination of banned azo dyes in leather has been studied. Thus, optimization of experimental conditions in different steps (degreasing, reduction, and extraction) of the analytical procedure was performed. The influence of different variables (reaction time, temperature, and concentration of reducing agent) on the reduction process was evaluated by use of a factorial design. It was found that the concentration of the reducing agent and the interaction between time and temperature were the most influential variables. Consequently, by applying a higher temperature, the reaction time could be halved. The use of acidified water as extraction solvent in MAE was also investigated. Usually 1 mol L-1 HCl was superior to methanol and buffer in terms of extraction efficiency. In conclusion, the present method gave significantly higher recoveries in comparison with the original method. All dyes were determined indirectly by measuring their corresponding harmful amines, formed after reduction by use of sodium dithionite.
|
|
| 9. |
- Bak, Søren Alex, et al.
(författare)
-
Occurrence of ionophores in the Danish environment
- 2014
-
Ingår i: Antibiotics. - 2079-6382. ; 3:4, s. 564-571
-
Tidskriftsartikel (refereegranskat)abstract
- Antibiotics in the environment are a potential threat to environmental ecosystems as well as human health and safety. Antibiotics are designed to have a biological effect at low doses, and the low levels detected in the environment have turned focus on the need for more research on environmental occurrence and fate, to assess the risk and requirement for future regulation. This article describes the first occurrence study of the antibiotic polyether ionophores (lasalocid, monensin, narasin, and salinomycin) in the Danish environment. Various environmental matrices (river water, sediment, and soil) have been evaluated during two different sampling campaigns carried out in July 2011 and October 2012 in an agricultural area of Zealand, Denmark. Lasalocid was not detected in any of the samples. Monensin was measured at a concentration up to 20 ng·L−1 in river water and 13 µg·kg−1 dry weight in the sediment as well as being the most frequently detected ionophore in the soil samples with concentrations up to 8 µg·kg−1 dry weight. Narasin was measured in sediment samples at 2 µg·kg−1 dry weight and in soil between 1 and 18 µg·kg−1 dry weight. Salinomycin was detected in a single soil sample at a concentration of 30 µg·kg−1 dry weight.
|
|
| 10. |
- Bak, Søren Alex, et al.
(författare)
-
Occurrence of ionophores in the Danish environment
- 2014
-
Ingår i: Antibiotics. - : MDPI Multidisciplinary Digital Publishing Institute. - 2079-6382. ; 3:4, s. 564-571
-
Tidskriftsartikel (refereegranskat)abstract
- Antibiotics in the environment are a potential threat to environmental ecosystems as well as human health and safety. Antibiotics are designed to have a biological effect at low doses, and the low levels detected in the environment have turned focus on the need for more research on environmental occurrence and fate, to assess the risk and requirement for future regulation. This article describes the first occurrence study of the antibiotic polyether ionophores (lasalocid, monensin, narasin, and salinomycin) in the Danish environment. Various environmental matrices (river water, sediment, and soil) have been evaluated during two different sampling campaigns carried out in July 2011 and October 2012 in an agricultural area of Zealand, Denmark. Lasalocid was not detected in any of the samples. Monensin was measured at a concentration up to 20 ng·L−1 in river water and 13 µg·kg−1 dry weight in the sediment as well as being the most frequently detected ionophore in the soil samples with concentrations up to 8 µg·kg−1 dry weight. Narasin was measured in sediment samples at 2 µg·kg−1 dry weight and in soil between 1 and 18 µg·kg−1 dry weight. Salinomycin was detected in a single soil sample at a concentration of 30 µg·kg−1 dry weight.
|
|
