| 1. |
- Jackmann, Natalja, 1968-, et al.
(författare)
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Vitamin D status in children with leukemia, its predictors, and association with outcome
- 2020
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Ingår i: Pediatric Blood & Cancer. - : Wiley. - 1545-5009 .- 1545-5017. ; 67:4, s. e28163-
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Children and adolescents with leukemia are potentially at high risk of vitamin D inadequacy, which may have clinical relevance for skeletal morbidity, infections, and cancer outcome. This study aimed to evaluate vitamin D status at the time of diagnosis to investigate its predictors and association with overall survival in children with leukemia. PROCEDURE: We included all 295 children and adolescents diagnosed with leukemia at our institution between 1990 and 2016 who had available serum sample from the time of diagnosis. We analyzed serum 25-hydroxyvitamin D and parathyroid hormone levels and correlated them with clinical data. RESULTS: The 25-hydroxyvitamin D level was deficient (< 25 nmol/L), insufficient (25-50 nmol/L), sufficient (50-75 nmol/L), and optimal (> 75 nmol/L) in 6.4%, 26.8%, 39.7%, and 27.1% of the children, respectively. Older age and a more recent time of sampling (calendar year) predicted lower 25-hydroxyvitamin D level. In preschool children (age 6 years), the 25-hydroxyvitamin D level showed significant seasonal variation. CONCLUSION: It remains unclear whether vitamin D supplementation in pediatric leukemia patients will improve outcome.
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| 2. |
- Kågedal, Bertil, 1943-, et al.
(författare)
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Determination of glomerular filtration rate, a spin off aftercontrast-enhanced computed tomography among criticallyill patients − proof of concept
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Background Recently, Gong et al. (Gong et al. 2022) showed, in nine heathy subjects, that plasma clearance of high doses of iohexol given as contrast enhanced computed tomography (CT) could be used for determination of glomerular filtration rate (GFR). We utilized high doses of iohexol from angiographic or other contrast enhanced CT given to critical ill patients for calculation of GFRiohexol and compared these data with standard low dose iohexol GFR determinations.Method Patients at intensive care units (ICUs) in Southeast Sweden intended for radiographic investigations that included injection of 45-120 ml of iohexol (Omnipaque) were included, and the concentration of iohexol in plasma was measured by HPLC. Iohexol clearance was calculated by the method of Bröchner-Mortensen. The following days was iohexol clearance determined using the standard low dose of 5 mL of iohexol. Sixteen patients admitted to ICUs were included in this pilot study.Results GFR after high dosing of iohexol at contrast enhanced CT could be measured for all sixteen critically ill patients. Patients with normal or increased renal function had neglectable iohexol concentrations the day following the CT scan. There was excellent correlation between GFR determination with high and standard low iohexol dosing among these 6 patients. Ten patients had decreased renal function and delayed elimination of iohexol, thus was not GFR measurement with low dose iohexol possible to analyse the day after CT scan with high dose iohexol.Conclusion This pilot study showed that GFR can be measured after high doses of iohexol at enhanced CT and compare well with the standard low dose of iohexol clearance determinations.
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| 3. |
- Nezirevic Dernroth, Dzeneta, 1969-, et al.
(författare)
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Gas chromatography-mass spectrometry analysis of pheomelanin degradation products
- 2009
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Ingår i: Journal of Chromatography A. - : Elsevier BV. - 0021-9673 .- 1873-3778. ; 1216:30, s. 5730-5739
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Tidskriftsartikel (refereegranskat)abstract
- Melanoma is most rapidly increasing in the white population and people with pheomelanin skin type are at high risk to develop melanoma. However, little is known about the pheomelanin structure and function, and further elucidation of this melanin is therefore an important task. A GC/MS method was developed based on hydriodic acid hydrolysis of pheomelanin in the urine. Derivatization was performed with ethyl chloroformate and ethanol:pyridine (4:1, v/v). N,O-Ethoxycarbonyl-ethyl esters were extracted with chloroform and analyzed by GC/MS. 4-Amino-3-hydroxyphenylaianine and 3-amino4-hydroxyphenylaianine together with one benzothiazinone and two benzothiazole compounds were detected and identified in hydrolyzed samples of synthetic pheomelanin and melanin from the urine of a patient with melanoma. These findings strongly suggest that heterocyclic pheomelanin-type units are incorporated in the pigment structures.
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| 4. |
- Nezirevic Dernroth, Dzeneta, 1969-, et al.
(författare)
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Hydrophilic interaction liquid chromatographic analysis of aminohydroxyphenylalanines from melanin pigments
- 2007
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Ingår i: Journal of Chromatography A. - : Elsevier BV. - 0021-9673 .- 1873-3778. ; 1163:1-2, s. 70-79
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Tidskriftsartikel (refereegranskat)abstract
- Malignant melanomas are more often seen in subjects with light colored skin who tan poorly than in persons who tan more rapidly. This has been attributed to the structure of their pigment, pheomelanin, which differs markedly from the eumelanin of persons with darker skin. To study the hydrolysis products of pheomelanin pigments a new method was developed for analysis of 4-amino-3-hydroxyphenylalanine (4-AHP) and 3-amino-4-hydroxyphenylalanine (3-AHP). Pheomelanin samples were hydrolyzed and extracted with solid-phase extraction columns using strong cation-exchange (SCX) cartridges. Separation of 4-AHP and 3-AHP was achieved on a ZIC-HILIC column (150 mm × 2.1 mm I.D.) with a mobile phase consisting of acetonitrile:0.1 M ammonium acetate buffer, pH 4.5 (82:18, v/v). Detection was performed with an electrochemical detector at +400 mV. Run time was 30 min. The limits of detection were 73 pg and 51 pg for 4-AHP and 3-AHP respectively, using 2 μl injections. Good linearity was found within the range 0.05-5.0 μg/ml. Absolute recovery was 70% and relative recovery was 100%. The AHPs were stable for 1 year in the hydrolyzed samples, for 4 days in the eluates from solid-phase sorbents stored in the refrigerator, and for 2 days diluted with mobile phase and stored in the autosampler at 10 °C. The within-day imprecision was <5% and the between-day imprecision was <7% for the two analytes. The method, applied to the analysis of pheomelanin in urine from human melanoma patients, allows the analysis of 30 samples in one set and is suitable for routine work with human hair and melanoma cells. By using the ZIC-HILIC stationary phase, ion-pairing reagents could be avoided, which makes the method suitable to further analysis of degradation products from pheomelanins using mass spectrometric detection. © 2007 Elsevier B.V. All rights reserved.
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| 5. |
- Nezirevic Dernroth, Dzeneta, 1969-
(författare)
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Pheomelanin markers in melanoma with reference to their excretion into urine
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Skin pigmentation is an important issue in most cultures. Until recently we have not understood the most important elements of pigmentation regarding detailed chemical structure. The synthesis of melanin is very complex, and although core enzymes, other important proteins, and parts of the melanin structure have been identified much information in this context awaits disclosure.The function of the melanocyte and the deposition of melanin pigments into the keratinocytes are very important in the protection against UV light. Melanin pigments consist of high-molecular structures often described as brown to black eumelanin and yellow to red pheomelanin. Eumelanin is photoprotective, whereas pheomelanin is believed to be carcinogenic after UV radiation. There is strong evidence that people of fair complexion with freckles who tan poorly are at higher risk of developing melanoma. These people have a higher pheomelanin to eumelanin ratio in their skin.Melanoma, one of the most widely spread cancers, is derived from melanocytes. There is accumulating evidence that pigment constitution is highly involved in the development of melanoma. We found that patients with advanced melanoma secrete substantial amounts of pigment structures into the urine, in particular those with diffuse melanosis. In subsequently performed experiments we purified these pigments and subjected the product to chemical degradation by either hydrogen peroxide oxidation or hydriodic hydrolysis. Several new chromatographic methods were developed for the structural analysis of these products. Structural analysis of new chromatographic peaks was performed. In conclusion, complex pheomelanin structures as well as low molecular weight pigments and free benzothiazoles have been identified in the urine of patients with melanoma and diffuse melanosis.The present thesis provides new insight into melanogenesis and melanoma progression. This opens the doorway to further approaches to the investigation of melanins and can help to understand fundamental problems about the structure and biosynthesis of natural melanins.
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| 6. |
- Nezirevic Dernroth, Dzeneta, 1969-, et al.
(författare)
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Pheomelanin-related benzothiazole isomers in the urine of patients with diffuse melanosis of melanoma
- 2010
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Ingår i: Clinica Chimica Acta. - : lsevier Science B.V., Amsterdam. - 0009-8981 .- 1873-3492. ; 411:17-18, s. 1195-1203
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Tidskriftsartikel (refereegranskat)abstract
- Currently used as structural markers for pheomelanin identification and quantitation, benzothiazole compounds derived from isomeric cysteinyldopas have been indicated by recent in vitro studies as new potential pheomelanogenesis intermediates. Prompted by previous reports on the occurrence of large amounts of 5-S-cysteinyldopa (5-S-CD) and trichochromes in urine of patient with diffuse melanosis of melanoma we investigated the presence of benzothiazole compounds in the urine of these patients. Hydrophilic interaction liquid chromatography on zwitterionic stationary phase (ZIC-HILIC) and photo-diode array (PDA) detection was used for analysis of 6-(2-amino-2-carboxyethyl)-4-hydroxybenzothiazole-2-carboxylic acid (BTCA-5), and 7-(2-amino-2-carboxyethyl)-4-hydroxybenzothiazole-2-carboxylic acid (BTCA-2), derived from 5-S-CD and 2-S-cysteinyldopa (2-S-CD) isomers, respectively. Isocratic mobile phase with minimal sample preparation allowed efficient separation of the compounds, which were safely identified by their typical absorption features. Among 21 melanoma patients examined three showed diffuse melanosis. The levels of urinary BTCAs were found to be highly associated with melanosis but more loosely to excreted 5-S-CD. Analysis of the pigmented fraction of urine following alkaline hydrogen peroxide degradation and quantitation of BTCAs provided evidence for the presence of pheomelanins at higher levels in patients with melanosis.
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| 7. |
- Tesselaar, Erik, 1977-, et al.
(författare)
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Acute effects of coffee on skin blood flow and microvascular function
- 2017
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Ingår i: Microvascular Research. - : Academic Press. - 0026-2862 .- 1095-9319. ; 114, s. 58-64
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Tidskriftsartikel (refereegranskat)abstract
- ObjectiveStudies on the acute effects of coffee on the microcirculation have shown contradicting results. This study aimed to investigate if intake of caffeine-containing coffee changes blood flow and microvascular reactivity in the skin.MethodsWe measured acute changes in cutaneous vascular conductance (CVC) in the forearm and the tip of the finger, the microvascular response to transdermaliontophoresis of acetylcholine (ACh) and sodium nitroprusside (SNP) and post-occlusive reactive hyperemia (PORH) in the skin, after intake of caffeinated or decaffeinated coffee.ResultsVasodilatation during iontophoresis of ACh was significantly stronger after intake of caffeinated coffee compared to after intake of decaffeinated coffee (1.26 ± 0.20 PU/mm Hg vs. 1.13 ± 0.38 PU/mm Hg, P < 0.001). Forearm CVC before and after PORH were not affected by caffeinated and decaffeinated coffee. After intake of caffeinated coffee, a more pronounced decrease in CVC in the fingertip was observed compared to after intake of decaffeinated coffee (− 1.36 PU/mm Hg vs. − 0.52 PU/mm Hg, P = 0.002).ConclusionsCaffeine, as ingested by drinking caffeinated coffee acutely improves endothelium-dependent microvascular responses in the forearm skin, while endothelium-independent responses to PORH and SNP iontophoresis are not affected. Blood flow in the fingertip decreases markedly during the first hour after drinking caffeinated coffee compared to decaffeinated coffee.
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