Development of a time-resolved immunochromatographic test strip for rapid and quantitative determination of retinol-binding protein 4 in urine.

Urine retinol-binding protein 4 (RBP4) has recently been reported as a novel earlier biomarker of chronic kidney disease (CKD) which is a global public health problem with high morbidity and mortality. Accurate and rapid detection of urine RBP4 is essential for early monitor of impaired kidney function and prevention of CKD progression. In the present study, we developed a time-resolved fluorescence immunochromatographic test strip (TRFIS) for the quantitative and rapid detection of urine RBP4. This TRFIS possessed excellent linearity ranging from 0.024 to 12.50 ng/mL for the detection of urine RBP4, and displayed a good linearity (Y = 239,581 × X + 617,238, R2 = 0.9902), with the lowest visual detection limit of 0.049 ng/mL. This TRFIS allows for quantitative detection of urine RBP4 within 15 min and shows high specificity. The intra-batch coefficient of variation (CV) and the inter-batch CV were both < 8%, respectively. Additionally, this TRFIS was applied to detect RBP4 in the urine samples from healthy donors and patients with CKD, and the results of TRFIS could efficiently discern the patients with CKD from the healthy donors. The developed TRFIS has the characteristics of high sensitivity, high accuracy, and a wide linear range, and is suitable for rapid and quantitative determination of urine RBP4.

Synthesis of cholesterol analogues and comparison on their effect on plasma cholesterol with ß-Sitosterol.

The application of plant sterols in the treatment of hypercholesterolemia is promising. We hypothesize that plant sterols can reduce blood cholesterol because they have a side chain of at least three branches. Three cholesterol analogues were synthesized: CA0 (no side chain), CA3 (a 3­carbon chain with one branch), and CA14 (a 14­carbon side chain with two branches), and then compared their effect on blood cholesterol with that of ß-sitosterol. Structurally, ß-sitosterol has a 10­carbon side chain with three branches. Results demonstrated that ß-sitosterol could effectively reduce plasma total cholesterol (TC) by 20.3%, whereas CA0, CA3 and CA14 did not affect plasma TC in hypercholesterolemia hamsters. ß-Sitosterol was absent in the plasma and liver, indicating it was not absorbed. We concluded that ß-sitosterol with three branches had plasma TC-lowering activity. In contrast, cholesterol analogues with a side chain of two or fewer branches did not affect plasma cholesterol.