Reliability of scar assessments performed with an integrated skin testing device - the DermaLab Combo(®).

BACKGROUND: The DermaLab Combo(®) is a device with potential to make objective measurements of key scar components - pigmentation, vascularity, pliability and thickness. This study assessed the inter-rater and test-retest reliability of these measurements. METHOD: Three raters performed scar assessments on thirty patients with burn scars using the DermaLab Combo(®). Measurements of pigmentation, vascularity, pliability and thickness were made and intra-class correlation coefficients (ICC) were derived for inter-rater and test-retest reliability. RESULTS: Inter-rater reliability was found to be "excellent" in the 'best' and 'worst' areas of the index scar and normal skin for pigmentation (ICC: 0.94-0.98) and thickness (ICC: 0.86-0.96). Test-retest reliability was also "excellent" for pigmentation (ICC: 0.87-0.89) and thickness (ICC: 0.92-0.97) in all areas. Vascularity showed "good" to "excellent" inter-rater reliability (ICC: 0.66-0.84) in all areas however test-retest reliability was "low" (ICC: 0.29-0.42). Test-retest reliability was "excellent" for pliability (ICC: 0.76-0.91). Technical limitations were encountered making measurements in some scars for thickness, and in particular, pliability. CONCLUSION: The DermaLab Combo(®) measured pigmentation, thickness and pliability with "excellent" reliability. If future studies provide protocols to improve test-retest reliability of vascularity measurements and obtain pliability measurements more successfully, the DermaLab Combo(®) will be valuable device for scar assessment.

Oxidative stress generated damage to DNA by gastrointestinal exposure to insoluble particles.

There is growing concern that gastrointestinal exposure to particles is associated with increased risk of toxicity to internal organs and carcinogenicity. The mechanism of action is related to particle-induced oxidative stress and oxidation of DNA. Observations from animal models indicate that gastrointestinal exposure to single-walled carbon nanotubes (SWCNT), fullerenes C60, carbon black, titanium dioxide and diesel exhaust particles generates oxidized DNA base lesions in organs such as the bone marrow, liver and lung. Oral exposure to nanosized carbon black has also been associated with increased level of lipid peroxidation derived exocyclic DNA adducts in the liver, suggesting multiple pathways of oxidative stress for particle-generated damage to DNA. At equal dose, diesel exhaust particles (SRM2975) generated larger levels of 8-oxo-7,8-dihydro-2'-deoxyguanosine in rat liver than carbon black (Printex 90) did, whereas exposure to fullerenes C60 and SWCNT was the least potent. This ranking of samples was also observed for oxidatively damaged DNA in cultured cells. The extent of translocation from the gut is largely unresolved. However, there is evidence indicating that gastrointestinal exposure to particulate matter is associated with oxidative damage to DNA and this might be associated with increased risk of cancer.

Dipeptidyl peptidase IV inhibition reduces the degradation and clearance of GIP and potentiates its insulinotropic and antihyperglycemic effects in anesthetized pigs.

Glucose-dependent insulinotropic peptide (GIP) is known to be degraded by dipeptidyl peptidase IV (DPP IV), forming an inactive metabolite, but the extent of the enzyme's role in regulating the biological activity of GIP in vivo is still largely unknown. In nonfasted anesthetized pigs given an intravenous infusion of GIP, the intact peptide (determined by a novel NH(2)-terminally directed radioimmunoassay) accounts for only 14.5 +/- 2.5% of total immunoreactivity. This is increased (to 40.9 +/- 0.9%, P < 0.0001) by coadministration of valine-pyrrolidide (a specific DPP IV inhibitor) at a dose that completely inhibits plasma DPP IV activity. The plasma t(1/2) of intact GIP is prolonged by the inhibitor (from 3.3 +/- 0.3 to 8.1 +/- 0.6 min; P < 0.001), whereas the t(1/2) for COOH-terminal immunoreactivity is unaffected (13.2 +/- 0.5 and 11.5 +/- 0.8 min, pre- and postinhibitor). Measurement of arteriovenous concentration differences revealed that the liver, kidney, and extremities are the main sites of removal of exogenous intact GIP (organ extractions, 28.0 +/- 2.2, 26.3 +/- 5.7, and 21.8 +/- 3.0%, respectively). These organ extractions are reduced (P < 0.02) but not eliminated (kidney and extremities) by valine-pyrrolidide (to 6.5 +/- 4.6, 14.1 +/- 3.1, and 13.9 +/- 2.4%, respectively). Valine-pyrrolidide potentiates the insulinotropic effect of GIP (P < 0.02), resulting in an enhanced glucose disappearance rate (k, from 8.0 +/- 0.5 to 15.5 +/- 2.2%/min; P < 0.01) and a reduction in the glucose excursion after an intravenous glucose load (area under the curve, from 133 +/- 23 to 75 +/- 9 min. mmol/l; P < 0.05). These results suggest that DPP IV plays an important role in GIP metabolism but is not the sole enzyme responsible for its NH(2)-terminal degradation. Nevertheless, DPP IV inhibition increases the proportion of intact peptide sufficiently to enhance its insulinotropic and antihyperglycemic effects.

Numerical investigation of mode coupling in sinusoidally modulated GRIN planar waveguides.

We study mode coupling in planar 2-D graded-index optical waveguides with the beam propagation method. In particular we examine the effect of periodic radial deformations along the axis of a parabolic refractiveindex waveguide and compare our results to the results of perturbation theory.