A Novel Method to Determine Patient Skin Type: The Skin Analyzer.

Measuring skin color for medical research in an objective and nonbiased manner usually requires expensive equipment such as spectrophotometry and requires the subject to be present in person. We present a novel method to measure skin color from photographs using the Skin Analyzer application as a more effective, accessible, and efficient alternative. A desktop application, the Skin Analyzer, was developed to convert skin samples collected from digital images to the L*a*b color space and uses those values to calculate an individual typology angle that correlates to a Fitzpatrick skin type. To assess accuracy in variable lighting, six known colors representing the six Fitzpatrick skin types were printed and photographed in 15 separate locations within the hospital. To account for user variability in sample selection, interrater reliability was calculated with data generated by 13 untrained users testing the app on six subjects. The accuracy of measuring known values, which is the classification accuracy, was calculated to be 80%. Krippendorff alpha test was used to evaluate interrater reliability. The obtained alpha of 0.84 indicates a high interrater reliability. The high accuracy and reliability make the Skin Analyzer a suitable method of objectively determining Fitzpatrick skin type from images. The app may be used to investigate the effects of skin tone in various areas of interest, especially in retrospective studies where skin colorimeters cannot be used.

Nucleation of fibronectin fibril assembly requires binding between heparin and the 13th type III module of fibronectin.

Fibronectin (FN), a critical component of the extracellular matrix, is assembled into fibrils through a cell-mediated process. Heparan sulfate (HS) binds to the III13 module of FN, and fibroblasts lacking this glycosaminoglycan exhibit reduced FN fibril assembly. To determine if HS depends on III13 to control FN assembly, we deleted both III13 alleles in NIH 3T3 cells using the CRISPR-Cas9 system. ΔIII13 cells assembled fewer FN matrix fibrils and less DOC-insoluble FN matrix than wildtype cells. Little if any mutant FN matrix was assembled when purified ΔIII13 FN was provided to Chinese hamster ovary (CHO) cells, showing that lack of III13 caused the deficiency in assembly by ΔIII13 cells. Addition of heparin promoted the assembly of wildtype FN by CHO cells, but it had no effect on the assembly of ΔIII13 FN. Furthermore, heparin binding stabilized the folded conformation of III13 and prevented it from self-associating with increasing temperature suggesting that stabilization by HS/heparin binding might regulate interactions between III13 and other FN modules. This effect would be particularly important at matrix assembly sites where our data show that ΔIII13 cells require both exogenous wildtype FN and heparin in the culture medium to maximize assembly site formation. Our results show that heparin-promoted growth of fibril nucleation sites is dependent on III13. We conclude that HS/heparin binds to III13 to promote and control the nucleation and development of FN fibrils.