Search

Background Molecular skin profiling techniques, typically performed on skin samples taken by punch biopsy, have enhanced the understanding of the pathophysiology of atopic dermatitis (AD), thereby enabling the development of novel targeted therapeutics. However, punch biopsies are not always feasible or desirable, and novel minimally invasive methods such as skin tape stripping have been developed. Aim To develop, optimize and validate a novel tape stripping method guided by noninvasive in vivo skin imaging to sample atopic skin in children. Methods Skin tape stripping-based procedures were compared and optimized using data from 30 healthy controls (HCs: 5 adults, 25 children) and 39 atopic children. Evaluations were guided by high-resolution photography, reflectance confocal microscopy, optical coherence tomography and transepidermal water loss measurements. We assessed and compared adverse events (AEs), the time needed to perform the sampling and the cDNA levels obtained from the tapes. Results Tape stripping methods based on previously described protocols resulted in erosions in all participants and required a median time of 65 min to perform (range 60–70 min), but provided good cDNA yield. Shorter durations appeared less invasive but provided lower cDNA yield. The final optimized tape stripping protocol, using 11 tapes of 22 mm in diameter, each applied twice for 5 s with 90° rotation, did not produce significant AEs, was completed within a median time of 7 min (range 5–15 min) and provided good cDNA yield both in HCs and atopic children. Conclusion Our minimally invasive method is safe and reliable, and provides reproducible acquisition of cDNA in atopic children. In addition, it enables rapid sample collection, a crucial factor in clinical practice., BACKGROUND: Molecular skin profiling techniques, typically performed on skin samples taken by punch biopsy, have enhanced the understanding of the pathophysiology of atopic dermatitis (AD), thereby enabling the development of novel targeted therapeutics. However, punch biopsies are not always feasible or desirable, and novel minimally invasive methods such as skin tape stripping have been developed. AIM: To develop, optimize and validate a novel tape stripping method guided by noninvasive in vivo skin imaging to sample atopic skin in children. METHODS: Skin tape stripping-based procedures were compared and optimized using data from 30 healthy controls (HCs: 5 adults, 25 children) and 39 atopic children. Evaluations were guided by high-resolution photography, reflectance confocal microscopy, optical coherence tomography and transepidermal water loss measurements. We assessed and compared adverse events (AEs), the time needed to perform the sampling and the cDNA levels obtained from the tapes. RESULTS: Tape stripping methods based on previously described protocols resulted in erosions in all participants and required a median time of 65 min to perform (range 60-70 min), but provided good cDNA yield. Shorter durations appeared less invasive but provided lower cDNA yield. The final optimized tape stripping protocol, using 11 tapes of 22 mm in diameter, each applied twice for 5 s with 90° rotation, did not produce significant AEs, was completed within a median time of 7 min (range 5-15 min) and provided good cDNA yield both in HCs and atopic children. CONCLUSION: Our minimally invasive method is safe and reliable, and provides reproducible acquisition of cDNA in atopic children. In addition, it enables rapid sample collection, a crucial factor in clinical practice.

Yield stress is an important rheological parameter in mineral processing, including grinding and the thickening of concentrates and tailings. A yield stress model based on the concept of degrees of freedom of a particulate system in an aqueous medium is described. The model involves the maximum fraction of packing, which is related to the interaction between the particles that form the suspension. The model was experimentally validated using quartz suspensions with solids concentrations expressed as the volume fraction of solids in the range 0.25-0.51. The model successfully predicted the effect of a wide range of particle sizes on the yield stress. Suspensions of fine particles have packing values of low density in relation to the coarse sizes. Concentrations close to maximum packing lead to very high yield stress values. The model was also applied to predict the critical concentration of the solids in the discharge of an industrial Cu tailings thickener at Codelco Norte, Chile. The maximum fraction of packing in the thickening discharge was 0.35., Yield stress is an important rheological parameter in mineral processing, including grinding and the thickening of concentrates and tailings. A yield stress model based on the concept of degrees of freedom of a particulate system in an aqueous medium is described. The model involves the maximum fraction of packing, which is related to the interaction between the particles that form the suspension. The model was experimentally validated using quartz suspensions with solids concentrations expressed as the volume fraction of solids in the range 0.25-0.51. The model successfully predicted the effect of a wide range of particle sizes on the yield stress. Suspensions of fine particles have packing values of low density in relation to the coarse sizes. Concentrations close to maximum packing lead to very high yield stress values. The model was also applied to predict the critical concentration of the solids in the discharge of an industrial Cu tailings thickener at Codelco Norte, Chile. The maximum fraction of packing in the thickening discharge was 0.35.