| 1. |
- Svedman, Christer, et al.
(författare)
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Plasma proteins in a standardised skin mini-erosion (I): permeability changes as a function of time
- 2002
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Ingår i: BMC Dermatology. - : Springer Science and Business Media LLC. - 1471-5945. ; 2:1, s. 3-3
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: A standardised technique using a suction-induced mini-erosion that allows serial sampling of dermal interstitial fluid (IF) for 5 to 6 days has been described. In the present study, we studied permeability changes as a function of time. METHODS: We examined IF concentrations of total protein concentration and the concentration of insulin (6.6 kDa), prealbumin (55 kDa), albumin (66 kDa), transferrin (80 kDa), IgG (150 kDa) and alpha-2-macroglobulin (720 kDa) as a function of time, using an extraction pressure of 200 mmHg below atmospheric. RESULTS: At 0 h after forming the erosion, mean total IF protein content (relative to plasma) was 26 ± 13% (SD). For the individual proteins, the relative mean concentrations were 65 ± 36% for insulin, 48 ± 12% for albumin, 30 ± 19% for transferrin, 31 ± 15%for IgG and 19.5 ± 10% for alpha-2-macroglobulin. At 24 h, the total IF protein content was higher than at 0 h (56 ± 26% vs 26 ± 13%; p < 0.05, diff: 115%), as were some of the individual protein concentrations: prealbumin (50 ± 24 vs 25 ± 13%; p < 0.05), albumin (68 ± 21 vs 48 ± 12%; p < 0.05) and IgG (55 ± 30 vs 31 ± 15%; p = 0.05). ln the interval 24 h to 96 h the concentrations were relatively unchanged. CONCLUSIONS: The results indicate that fluid sampled at 0 h after forming the erosion represents dermal IF before the full onset of inflammation. From 24 h onward, the sampled fluid reflects a steady state of increased permeability induced by inflammation. This technique is promising as a tool for clinically sampling substances that are freely distributed in the body and as a model for studying inflammation and vascular permeability.
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| 2. |
- Svedman, Christer, et al.
(författare)
-
Plasma proteins in a standardised skin mini-erosion (II): effects of extraction pressure.
- 2002
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Ingår i: BMC Dermatology. - 1471-5945. ; 2:1, s. 4-4
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: A standardised suction technique has been used to sample plasma proteins in dermal interstitial fluid (IF) serially for 5 to 6 days from a suction-induced skin mini-erosion. Increased protein concentrations ascribed to inflammation have been shown from day 1 onward. In this study, we assessed the effect of two different extraction pressures on IF sample composition. METHODS: Total protein concentration and the concentrations of insulin, prealbumin, albumin, transferrin, IgG and alpha-2-macroglobulin were assessed daily in healthy volunteers. Samples were extracted at 50 mmHg and 200 mmHg below the atmospheric. RESULTS: At 0 h after forming the erosion, mean total IF protein content (relative to plasma) was lower in the samples extracted at -200 mmHg than at -50 mmHg (26 +/-13% (SD) vs 48 +/-9.8%; p < 0.05). There were no significant differences at 24, 48, 72 or 96 h. Of the individual proteins, expressed as area units (AU) for area under the curve (AUC) from 0&#ndash;96 h, albumin was lower in IF sampled at -200 mmHg (2.49 +/- 0.68 vs 3.08 +/- 0.36 AU; p < 0.05), as was transferrin (1.91 +/- 0.52 vs 2.40 +/- 0.42 AU; p < 0.05). Extraction volumes were significantly higher at -200 mmHg (AUC diff: 60%; p < 0.05). CONCLUSIONS: Samples of IF extracted at 0 h at -200 mmHg contained lower protein concentrations, indicating an increased water fraction and an intact sieve function of the vascular wall. The difference in protein concentration extracted at higher and lower pressure from 24 h onward was less pronounced. Lower pressure should be used to sample substances of greater molecular size.
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| 3. |
- Svedman, Christer
(författare)
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Sampling from a suction induced mini-erosion in human skin. Methodological studies.
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Dermal interstitial fluid (IF) was extracted serially and painlessly by brief suction for as long as 6 days. The erosion was otherwise kept occluded, Sample volumes exceded those required for measuring a wide range of biological substances. Epidermal regeneration was rapid. Glucose concentrations in IF and plasma, measured in diabetic and non-diabetic subjects for as long as 6 days were closely correlated over a wide range of values. During oral glucose tolerance tests on days 1 and 3 after forming the erosion, the IF OGTT curves for glucose, 3-hydroxybutyrate and glycerol were very similar to plasma. IF lactate curves were higher than in plasma, reflecting glycolytic activity , whereas insulin curves were lower, reflecting vascular permeability. A potential is suggested for clinical sampling of glucose in subjects with diabetes mellitus, and for experimental monitoring of dermal metabolism. The IF concentration of plasma proteins (size range 6-720 kDa) measured in IF on day 1 in healthy volunteers was consistent with findings obtained with other techniques. From day 2 to 5, the sample fluid reflected a steady state of increased permeability induced by mild inflammation. IF samples extracted on day 1 using greater negative pressure had lower protein concentrations than those extracted at lower pressure, indicating an increased water fraction and an intact sieve function of the vascular wall. The differences were less pronounced on days 2-5. Extraction volumes were dependent on the extraction pressure on all days. The findings indicate the usefulness of the technique for clinical experimental purposes.
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