Studies on the Distribution and Radioimmunoimaging of ^(99m)Tc-Labeled 5-Fluorouracil Loaded Immunological Nanoparticles in Tissues and Human Gastric Carcinoma Xenografts

OBJECTIVE To explore the method of preparation of 99mTc labeled AntiVEGF McAb 5-FU loaded polylactic acid nanoparticles(99mTc-5-FU-Ab-NPs), and investigate the biological distribution of the nanoparticles in human gas- tric carcinoma xenografts. METHODS Anti-VEGF monoclonal antibodyes(MCAB)in 5-FU-Ab-NPs were labeled with 99mTc using a modified Schwarz method.After isolation of the 99mTc-5-FU-Ab-NPs using a Sephadex G-250 column,the labeling percentage and radiochemical purity were determined using paper chromatog- raphy.The immunocompetence of the 99mTc-5-FU-Ab-NPs as tumor markers was determined using ELISA and immunohistochemistry.99mTc-5-FU-Ab-NPs (experimental group),99mTc-labelled murine multiclonal IgG loaded polylactic acid and nanoparticles(control group)were injected via the tail vein into SCID mice bearing human gastric carcinoma.A radio-immunity ECT image was developed at 2 and 6 h after the injection.Following the ECT imaging, the mice were sacrificed,their tissue and tumor radioactivity distribution determined,and percentage of the injected-dose per gram(%ID/g)and tumor/ nontumor(T/NT)ratio calculated.High performance liquid chromatography (HPLC)was used to determine the 5-FU concentration in the tumor tissue and blood in the mice of both groups. RESULTS The percentage of 99mTc-5-FU-Ab-NPs labeling was 90%~95%.There was no obvious decrease in the antibody activity before and after labeling.The radio-immuno-imaging(RII)showed that the tumor image had developed 2 h after injection of the 99mTc-5-FU-Ab-NPs,and with time it was clearer at the 6th hour fol owing the injection.The%ID/g of the tumor tissue at both 2 h and 6 h after the injection was significantly higher compared to the control group.The tumor%ID/g and the tumor to blood activity ratio(TB)of the experimental group at 6 h following the injection increased compared to that at 2 h,and at the same time,5-FU concentration in the tumor of the experimental group continuously increased over time,and showed a significant difference compared to the 5-FU concentration in the tumor of the control group. CONCLUSION The 99mTc-5-FU-Ab-NPs prepared in this study are adequate to meet the demands of the RII,and the immune targeting ability of the anti-VEGF MCAB is reliable.Six hours after injection,the 99mTc-5-FU-Ab-NPs showed a relatively high specific concentration shadow in the human gastric carcinoma xenografts.

Nitrogen Under-and Over-supply Induces Distinct Protein Responses in Maize Xylem Sap

Xylem sap primarily transports water and mineral nutrients such as nitrogen （N） from roots to shoots in vascular plants. However, it remains largely unknown how nitrogenous compounds, especially proteins in xylem sap, respond to N under- or over-supply. We found that reducing N supply increased amino-N percentage of total N in maize （Zea mays L.） xylem sap. Proteomic analysis showed that 23 proteins in the xylem sap of maize plants, including 12 newly identified ones, differentially accumulated in response to various N supplies. Fifteen of these 23 proteins were primarily involved in general abiotic or biotic stress responses, whereas the other five proteins appeared to respond largely to N under- or over-supply, suggesting distinct protein responses in maize xylem upon N under- and over-supply. Furthermore, one putative xylanase inhibitor and two putative O-glycosyl hydrolases had preferential gene expression in shoots.

Development and challenges of green food in China

Green food in China refers to a wide array of primary and processed agricultural products that are safe,nutritious and of high quality for human consumption.Green food has been certified and produced following the principle of sustainability since the 1990 s,making historic achievements in providing quality food,protecting the environment,increasing farmer income,and nurturing agricultural brands over the past 30 years in China.Today,the green food industry enters a steady-growth stage in terms of cultivation area,product number and sales.This article summarizes the history of the development of green food in China and current achievements,analyze major challenges that may hamper further development of the industry,and propose strategies to address these challenges,i.e.,optimization of the food supply chain,deep food processing,and utilization of food wastes.