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  • 1
    Electronic Resource
    Electronic Resource
    Copenhagen : Munksgaard International Publishers
    Experimental dermatology 10 (2001), S. 0 
    ISSN: 1600-0625
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Mastocytosis represents a group of disorders characterized by the proliferation and accumulation of mast cells in tissue. The aim of the present study was to examine whether the interstitial histamine concentration in the skin is increased in mastocytosis patients and whether it correlates with the number of mast cells, the amount of metabolite N-methyl-imidazole acetic acid in the urine and the tryptase in serum. In 7 mastocytosis patients on a standardized diet, the analysis of histamine was performed on microdialysates obtained from catheters positioned intracutaneously in involved and uninvolved skin. N-methyl-imidazole acetic acid in the urine was collected for 24 h. Biopsies for analyses of mast cells were taken from skin adjacent to the microdialysis catheters. The histamine concentrations were 42±14, 12±3 (P〈0.05) and 8±2 nmol/l (mean±SEM, n=7) in skin eruptions, non-lesional skin and plasma respectively. Mean N-methyl-imidazole acetic acid in the urine (9.7±3.5 mmol/mol creatinine) and mean tryptase (124±54 μg/l) had increased in all patients. In the present study, no linear correlation was found between these parameters and interstitial histamine in lesional skin. This finding corresponds to the fact that the concentration of histamine metabolites and tryptase derives from the entire mast-cell population, while interstitial histamine in the dermis represents the local tissue concentration before metabolic transformation. The microdialysis of histamine in the skin of mastocytosis patients could be used as a tool to investigate the effects of dermal mast-cell histamine release in different kinds of treatment regimen.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Clinical and experimental dermatology 25 (2000), S. 0 
    ISSN: 1365-2230
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Delta-aminolevulinic acid (ALA) is used for photodynamic therapy of basal cell carcinoma (BCC) as it is converted to protoporphyrin IX in tumour tissue. During illumination with 635 nm light a photochemical reaction takes place, singlet oxygen is generated and the tumour destroyed. In this study we used the microdialysis technique to quantify the concentration of ALA at a certain depth in tumour and healthy skin. The penetration ability of ALA was investigated as a function of time in BCCs (n = 14) and in normal skin (n = 4) after topical application. The microdialysis catheters were inserted intracutaneously and the depth position recorded by means of ultrasound. Microdialysate sample concentrations of amino acids and ALA were determined by high performance ion-exchange chromatography. A laser Doppler perfusion imager measured perfusion in the BCCs. The data show that the average depth of the microdialysis catheters was 0.5 mm. The interstitial ALA concentration in the BCCs increased from 0 to 3.1 mmol/L 15 min after application of ALA, whereas no measurable amounts of ALA were found in healthy skin. The blood perfusion was 2.5-fold increased in the BCCs. The interstitial levels of amino acids were not significantly changed during the ALA treatment. In summary, we found that ALA rapidly penetrates tumour skin. We conclude that microdialysis seems to be well suited for pharmacodynamic studies of ALA in skin.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    British journal of dermatology 134 (1996), S. 0 
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: In this study we aimed to validate the microdialysis technique for metabolic measurements in the dermal interstitial fluid. The abdominal and forearm skin was used for microdialysis in 15 healthy normal weight volunteers. The depth of the microdialysis catheter was assessed by ultrasound measurement. Structural impairment and blood flow were judged from biopsies and from laser Doppler measurements taken adjacent to the catheters. Dermal interstitial lactate and pyruvate concentrations were measured, under steady stale fasting conditions, after equilibrium calibration of each catheter in situ. The dermal Interstitial glucose concentration was estimated by means of the retrodialysis calibration method, which has previously not been evaluated for skin microdialysis. The mean catheter depth (± standard deviation) was 0.8 ± 0.3 mm. Small areas of localized bleeding, but no inflammatory reaction, was found surrounding the catheters. The perfusion in the microdialysis region was slightly increased (15–25%1. The lactate/pyruvate ratio (12 ±0.7) showed non–ischaemic values. The dermal interstitial lactate concentration was significantly higher (1171 ± 228μmol/l) than the plasma lactate (781 ± 180μmol/l), indicating an ongoing nonoxidative glucose metabolism. Retrodialysis calibration correctly estimated the dermal glucose level to be similar to that in plasma, which may indicate the usefulness of this calibration method for microdialysis studies of endogenous substrates in the dermal interstitial fluid.
    Type of Medium: Electronic Resource
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