Total protein assay by PCA-based RGB-spectrum conversion methods with smartphone-acquired digital images.

Total protein concentrations in the aqueous solutions were determined from the absorption spectra reproduced from smartphone-captured digital color images. We employed two different procedures for protein determination: the pyrogallol red molybdate method and Bradford's method. The principal-component-analysis-based reproduction process, which was previously reported by our research group, enabled the conversion of RGB values to score values for a linear combination of loading vectors to generate reproduced absorption spectra. The reproduced spectra were identical to those measured using a commercially available spectrophotometer. The total protein assays of commercial soymilk and human serum samples were carried out with both coloration reagents, and the obtained results were in good agreement with those attained using a conventional spectrophotometer. These results show that the proposed method enables smartphone-based ratiometric analysis of real samples without requiring any monochromating equipment.

Comparison of the usefulness of the cardio-ankle vascular index and augmentation index as an index of arteriosclerosis in patients with essential hypertension.

Arteriosclerosis leads to various serious diseases that substantially reduce the quality of life. When treating hypertension, it is important to evaluate the degree of arteriosclerosis. In recent years, the cardio-ankle vascular index and augmentation index have been frequently used as indicators of arterial wall sclerosis. However, the superiority of either the cardio-ankle vascular index or the augmentation index as an index of arteriosclerosis remains unclear. Therefore, the present study compared the usefulness of these two indices as an index of arteriosclerosis. Associations between the cardio-ankle vascular index or augmentation index and risk factors for arteriosclerosis and other indices of arteriosclerosis in 535 consecutive patients with essential hypertension were evaluated. The cardio-ankle vascular index was significantly correlated with age, hemoglobin A1c, brain natriuretic peptide, and estimated glomerular filtration rate. In contrast, the augmentation index showed significant correlations only with age, brain natriuretic peptide, and estimated glomerular filtration rate. In addition, these correlations with the augmentation index were generally weaker than those with the cardio-ankle vascular index. The cardio-ankle vascular index, but not the augmentation index, was significantly correlated with flow-mediated dilation, an index of vascular endothelial function, and carotid intima-media thickness, an index of carotid atherosclerosis. Similar results were observed in subgroups stratified by sex and age. These data indicate that the cardio-ankle vascular index is more closely associated with risk factors for arteriosclerosis and other indices of arteriosclerosis than the augmentation index, suggesting that the cardio-ankle vascular index may be superior to the augmentation index as an index of arteriosclerosis.