RESUMO
A novel paper-based analytical device(PAD)was prepared and applied to determine the xanthine oxi-dase(XOD)inhibitory activity of Salvia miltiorrhiza extracts(SME).First,polycaprolactone was 3D printed on filter paper and heated to form hydrophobic barriers.Then the modified paper was cut according to the specific design.Necessary reagents including XOD for the colorimetric assay were immobilized on two separate pieces of paper.By simply adding phosphate buffer,the reaction was performed on the double-layer PAD.Quantitative results were obtained by analyzing the color intensity with the specialized device system(consisting of a smartphone,a detection box and sandwich plates).The 3D-printed detection box was small,with a size of 9.0 cm x 7.0 cm x 11.5 cm.Color component G performed well in terms of linearity and detection limits and thus was identified as the index.The reaction con-ditions were optimized using a definitive screening design.Moreover,a 10％glycerol solution was found to be a suitable stabilizer.When the stabilizer was added,the activity of XOD could be maintained for at least 15 days under 4℃or-20℃storage conditions.The inhibitory activity of SME was investigated and compared to that of allopurinol.The results obtained with the PAD showed agreement with those ob-tained with the microplate method.In conclusion,the proposed PAD method is simple,accurate and has a potential for point-of-care testing.It also holds promise for use in rapid quality testing of medicinal herbs,intermediate products,and preparations of traditional Chinese medicines.
RESUMO
Objective@#To learn the epidemiological characteristics of family clusters of COVID-19 in Henan Province from January 23 to February 22, 2020, so as to provide reference for the prevention and control. @*Methods@#The data of family clusters of COVID-19 in Henan Province from January 23 to February 22 was retrieved from Public Health Emergency Management System, the epidemiological characteristics of time, space, population distribution and clinical feasures were analyzed. @*Results@#By February 22, there were 202 family clusters of COVID-19, with 546 cases reported in Henan Province, including 493 ( 90.29% ) confirmed cases and 53 ( 9.71% ) asymptomatic cases. There were 247 ( 45.24% ) imported cases and 299 ( 54.76% ) local cases. Most of the clusters were reported from January 25 to February 7, with 129 clusters accounting for 63.86% . The cases reported before February 5 were mainly imported ( 153 cases, 57.09% ) , after that local cases were predominant ( 168 cases, 68.29% ) . Eighteen cities in Henan Province all reported family clusters of COVID-19, with Xinyang, Zhengzhou, Nanyang, Zhumadian and Shangqiu as the top five. Most of the confirmed cases ( 430, 87.22% ) were mild. The median and longest incubation period was 8 and 17 days, respectively. The intergenerational distribution was dominated by first-generation and second-generation cases ( 537 cases, 98.35% ) . A total of 5 635 close contacts were tracked down, of whom 262 were secondary cases, with an incidence rate of 4.65%. The first cases of the family clusters were mainly imported from other provinces ( 149 cases, 73.76% ) .@*Conclusions @#The family clusters of COVID-19 in Henan Province were concentrated from January 25 to February 7. The source of infection mainly comes from other provinces. Most of the cases are first-and second-generation cases, with longer incubation period. Close contacts have higher incidence rate.