Application of Lutein and Zeaxanthin in nonproliferative diabetic retinopathy

AIM: To compare serum Lutein and Zeaxanthin (L/Z) concentrations between patients with nonproliferative diabetic retinopathy (NDR) and normal subjects,and to explore the effect of L/Z supplementation on serum L/Z level and visual function in NDR patients METHODS: Subjects were divided into three groups: 30 NDR patients supplied with Lutein 6mg/d and Zeaxanthin 0.5mg/d for three months (DR Group),30 NDR patients without L/Z supplementation (DR Control Group) and 30 normal subjects (Control Group).Serum L/Z concentrations were measured by liquid high-resolution chromatography (HPLC).Visual acuity was recorded at baseline,1 month,2 months and 3 months post initial supplementation.Serum L/Z concentration were measured at baseline,1 month and 2 months post initial supplementation.Contrast sensitivity (CS) and fovea thickness were recorded at baseline and 3 months post initial supplementation.RESULTS: Mean serum lutein concentrations in DR group were 0.0686±0.0296μg/mL and zeaxanthin concentration was 0.0137±0.0059μg/mL.The L/Z level of DR group was significantly lower compared to the control group( lutein: 0.2302±0.1308μg/mL,zeaxanthin: 0.0456±0.0266μg/m,P = 0.000).The concentration of lutein and zeaxanthin in the DR control group at base line was 0.0714±0.0357μg/mL and 0.0119±0.0072μg/mL,respectively.There was no significant change of L/Z concentration in the DR control group during the study.Serum L/Z concentrations of DR group increased significantly after supplementation(F=109.124,P=0.000;F=219.207,P=0.000).Visual acuity improved significantly after medication.Compared with pre-medication,the average CS values of 1.5cpd,3cpd and 6cpd after three months increased significantly (P =0.030,0.013,0.008) and the foveal thickness decreased.(P =0.05) CONCLUSION: Serum L/Z concentrations in DR patients are significantly lower than those in normal subjects,and L/Z intake can improve the visual acuity,CS and macular edema in DR patients,suggesting that L/Z supplementation might be targeted as potential potential therapeutic agents in treating NDR.

Simultaneous Estimation of Multiple Conditional Regression Quantiles

In this article, we put forward a new approach to estimate multiple conditional regression quantiles simultaneously. Unlike the double summation method in most of the literatures, our proposed model allows continuous variety for the quantile level over(0,1). As a result, all the quantile curves can be obtained via a 2-dimensional surface simultaneously. Most importantly, the proposed minimizing criterion can be readily transformed to a linear programming problem. We use tensor product bi-linear quantile smoothing B-splines tofit it. The asymptotic property of the estimator is derived and a real data set is analyzed to demonstrate the proposed method.