Mesenchymal Stem Cells: A Promising Treatment for Thymic Involution.

The thymus is the main immune organ in the body. However, the thymus gradually degenerates in early life, leading to a reduction in T-cell production and a decrease in immune function. Mesenchymal stem cells (MSCs) are a promising alternative for the treatment of thymus senescence due to their homing ability to the site of inflammation and their paracrine, anti-inflammatory, and antioxidant properties. However, the heterogeneity, difficulty of survival in vivo, short residence time, and low homing efficiency of the injected MSCs affect the clinical therapeutic effect. This article reviews strategies to improve the efficacy of mesenchymal stem cell therapy, including the selection of appropriate cell doses, transplantation frequency, and interval cycles. The survival rate of MSCs can be improved to some extent by improving the infusion mode of MSCs, such as simulating the in vivo environment, applying the biological technology of hydrogels and microgels, and iron oxide labeling technology, which can improve the curative effect and homing of MSCs, promote the regeneration of thymic epithelial cells, and restore the function of the thymus.

[Application of gold nanoparticles-based lateral flow strip for dengue virus detection based on strand-displacement amplification].

OBJECTIVE: To investigate the rapid and accurate method for the detection of dengue virus (DENV) by using nicking enzyme assisted strand-displacement amplification (SDA) combined with gold nanoparticles-based lateral flow strip. METHODS: Total RNA of the virus was extracted by using magnetic beads method and transcribed to cDNA for SDA detection system. Nicking enzyme-assisted method was used for detecting DENV, and agarose gel electrophoresis was used for analyzing the sensitivity of SDA amplification products. A gold nanoparticles-based lateral flow strip was developed based on the principle of nucleic acid base complementary pairing to design the test line and control line. The gold particles were prepared by using sodium citrate reduction method for gold nanoparticles-based lateral flow strip construction. RESULTS: The sensitivity of the SDA method was 10 fmol/L, and the sensitivity of gold nanoparticles-based lateral flow strip based on SDA method was also 10 fmol/L. In a linear range from 10 fmol/L to 1012 fmol/L, the corresponding linear correlation coefficient (R2) of DENV was 0.98. The specificity of nanoparticles-based lateral flow strip based on SDA for DENV detection was high, which was no crossing with other control groups. CONCLUSIONS: A gold nanoparticles-based lateral flow strip based on SDA method for DENV detection has been established, which is convenient, fast, and the result is visible to naked eyes.

[Expression of g6pd gene in wild type zebrafish embryos of early development].

OBJECTIVE: : To observe the expression of g6pd gene in the early development stage of wild zebrafish embryos. METHODS: : The collinearity of g6pd gene and the sequence similarity of G6pd protein were analyzed with gene database and BLAST software, respectively. Expression of g6pd gene in different development stages of zebrafish embryos was detected by in situ hybridization. The g6pd-EGFP-pCS2+ recombinant plasmids were microinjected into zebrafish embryos, and fluorescence was observed under a fluorescence microscope. The expression of G6pd protein at 24, 48 and 72 hour post fertilization (hpf) zebrafish embryos was detected by Western blotting; the enzyme activity of G6pd at 24, 48 and 72 hpf zebrafish embryos was detected by modified G6pd quantitative ratio method. RESULTS: : The G6pd protein similarity of zebrafish and human was 88%, and that of zebrafish and mouse was 87%. The results of in situ hybridization showed that the g6pd gene was mainly expressed in the hematopoietic tissues of zebrafish; the results observed after microinjection of g6pd-EGFP-pCS2+ recombinant plasmid were consistent with the results of in situ hybridization. At 24, 48 and 72 hpf, the relative expression levels of G6pd protein in zebrafish embryos were 1.44±0.03, 1.47±0.05, and 1.54±0.02, respectively(P>0.05); the G6pd enzyme activity levels were 1.74±0.17, 1.75±0.12, 1.71±0.22, respectively (P>0.05). CONCLUSIONS: : The study has observed the expression of g6pd gene and G6pd protein, and G6pd enzyme activity in zebrafish embryos at different development phases, which provides a reference for the establishment of a zebrafish G6PD deficiency model.

A colorimetric assay for vanillin detection by determination of the luminescence of o-toluidine condensates.

Vanillin (4-hydroxy-3-methoxybenzaldehyde), a food additive with rich milk flavor, is commonly used in the food, beverage and cosmetic industries. However, excessive consumption of vanillin may cause liver and kidney damage. Therefore, methods for detecting and controlling the level of vanillin in food, especially in infant powder, have important practical significance. In this study, we established a colorimetric assay for vanillin detection. The detection was performed under high-temperature and acidic conditions, which can induce the reaction of the aldehyde group of vanillin with the amino group of o-toluidine. The resulting product had a maximum absorption at 363 nm, which was quantified by a UV spectrophotometer. This assay had a limit of detection (LOD) of 1 pg mL-1 and a linear range between 1 µg mL-1 and 100 µg mL-1. The average recoveries at three spiked levels were in the range from 91.1% to 101.6% with a relative standard deviation (RSD) of 4.62% ~ 7.27%.