ABSTRACT
【Objective】 To establish and evaluate a nephelometric assay for the determination of immunoglobulin A (IgA) residues in human intravenous immunoglobulin(IVIG). 【Methods】 BN ProSpec© automatic protein analyzer and its supporting immunoglobulin A determination kit (nephelometry) produced by German Siemens and the national standard of human IgA were used to establish the nephelometric assay to determine IgA residue in test products and verify the methodology. The test products include IVIG (pH4) prepared by low-temperature ethanol protein separation process and a novel IVIG prepared by chromatography. 【Results】 The average deviation of three calibration curves for IgA residues determination by the nephelometric assay were 1.08%, 0.95% and 1.54%,, and the three deviations of the quality control were 4.00%, -2.30% and -0.20%, respectively, which indicated good calibration and quality control. In the specificity test, the average recovery rates of IgA for reference substance 1 containing 100g/L maltose and reference substance 2 containing 20g/L glycine were 102.7% and 105.8%, respectively. The relative standard deviation (RSD) values of the repeatability tests of the two test products were 3.9% and 1.9%, and the RSD values of the intermediate precision test were 3.6% and 2.3%, respectively.The difference values at each time point in the durability test of test products′ storage time were all less than 10%, and the RSD values of the two test products in the durability test of kits of different batches were 2.8% and 2.2%, respectively. In the accuracy test, the average recovery rates of IVIG (pH4) added to the standard were 94.2%, 101.7% and 96.2%, respectively, and the average recovery rates of the novel IVIG added to the standard were 102.8%, 106.3% and 99.7%, respectively. The average recovery rate of the limit quantification test was 101.0%, and the RSD was 4.0%. 【Conclusion】 Nephelometric assay has the advantages of strong specificity, high precision and accuracy, good repeatability, simple and rapid operation, and automation, and can be used for the determination of IgA residue in IVIG (pH4) and novel IVIG products.
ABSTRACT
Objective To establish a stable and reliable mouse model as an alternative to the traditional model of impaired glucose tolerance induced by calorie restriction and its effect on glucose homeostasis.Methods Forty 16-week-old SPF C57BL/6J mice (half male and half female) were randomly divided into four groups by sex and the way of feeding.The mice in the ad libitum (AL) group had free access to basic diet, while the mice in the intermittent fasting (IF) group had normal diet and fasting on alternate days, with free access to water on the fasting days.The changes of body weight and blood glucose concentration in each group were monitored, and intraperitoneal glucose tolerance test and insulin tolerance test in mice were performed before and after the 12-week IF treatment.Results At 12 weeks after IF treatment, the body weight and blood glucose concentration of mice did not show significant difference.After i.p.injection of glucose, the blood glucose concentration of IF mice was less increased than the AL group, and after the insulin injection, the blood glucose concentration was more decreased.Compared to the AL group, the areas under the curve of tolerance test in the IF group were significantly decreased (P < 0.05).Conclusions After IF treatment, the mice show an enhanced sensitivity to insulin and improved glucose tolerance.This establishment method of mouse model of intermittent fasting is easy and simple, therefore, can be used as an effective alternative to traditional calorie restriction model of impaired glucose tolerance.