L-valine is an important essential branched-chain amino acid widely used in industries such as feed, pharmaceuticals, and food. In order to further enhance the production performance of L-valine, this study systematically engineered the metabolism of a Corynebacterium glutamicum strain, preserved in the laboratory, which is capable of producing L-valine. First, strain VH-9 was obtained by enhancing the precursor supply, synthesis pathway, and transport system of L-valine. In a 5 L fermenter, the titer, yield, and productivity of L-valine were 76.6 g/L, 0.45 g/g, and 2.39 g/(L·h), respectively. Furthermore, strain VH-18 was obtained by enhancing the uptake of substrate glucose and balancing energy supply to reduce succinate accumulation, with the titer, yield, and productivity of L-valine increased to 82.7 g/L, 0.52 g/g, and 2.58 g/(L·h), respectively. After optimization of fermentation conditions, the titer, yield, and productivity of L-valine in strain VH-18 were further improved to 88.7 g/L, 0.54 g/g, and 2.77 g/(L·h), respectively. This study has achieved the high-efficiency production of L-valine through a systems metabolic engineering strategy.
Corynebacterium glutamicum/genetics* ; Metabolic Engineering/methods* ; Valine/biosynthesis* ; Fermentation ; Glucose/metabolism*

Objective:To explore the phenomenon of spontaneous regression of optic pathway glioma in children, and to improve the understanding of optic pathway glioma.Methods:The clinical data of 3 patients with spontaneous regression of optic pathway glioma in Beijing Children's Hospital of Capital Medical University from September 2012 to June 2019 were retrospectively analyzed.Results:There were 2 girls and 1 boy among the 3 patients. The median age of onset was 4 months (3-5 months), the median age of tumor regression was 10 months (8-13 months), and the interval median time from onset to tumor regression was 5 months (4-10 months). One patient was accompanied with diencephalic syndrome, and the other was accompanied with disseminated metastasis.Conclusions:The phenomenon of spontaneous regression of optic pathway glioma mostly occurs in the early childhood. Optic pathway glioma pediatric patients complicated with diencephalic syndrome or intracranial metastasis may have the possibility of tumor regression, but spontaneous regression does not mean that the symptoms can be completely improved.

AIM: To investigate the effect of glomerular intercellular interaction under high glucose concentration on the production of reactive oxygen species (ROS) and transforming growth factor ?_1 (TGF-?_1) in co-cultured human ECV304 cells, and to study the intervention with tea polyphenols (TPs). METHODS: The endothelial cells were cultured alone or co-cultured with mesangial cells in high glucose media with or without TPs for 0 h, 12 h and 36 h, respectively. The activity of SOD and the content of MDA in the media of the system were detected by spectrophotometry. The expression of TGF-?_1 mRNA in the endothelial cells was measured by using semi-quantitative reverse transcription PCR (RT-PCR). RESULTS: High glucose decreased the activity of SOD, increased the content of MDA and up-regulated the expression of TGF-?_1 mRNA in co-cultured ECV304 cells and the effect became more prominent than the single-cultured cells. TPs interrupted it more effectively. CONCLUSION: These data suggest that there is interaction between mesangial cells and ECV304 cells under high glucose concentration. The interaction may markedly up-regulate the production of ROS and the expression of TGF-?_1 in co-cultured ECV304 cells. TPs may protect ECV304 cells by intervening intercellular interaction.