L-valine is an important branched-chain amino acid widely used in the food, pharmaceutical, and feed industries. Microbial fermentation has become the primary production method for L-valine. However, current industrial production still faces issues such as inefficient carbon flux utilization, imbalance in cofactor supply and demand, and suboptimal fermentation processes, which limit the efficient synthesis of L-valine. To further enhance the production performance of L-valine, In this study, metabolic engineering was conducted for a previously constructed Escherichia coli strain with a high yield of L-valine to optimize carbon flux distribution and balance cofactor consumption. Dual-phase oxygen-controlled fermentation was carried out to enhance L-valine production. Firstly, to address the pyruvate loss, we knocked out multiple competing pathway genes (ldhA, poxB, pflB, frdA, and pta), which resulted in a 48% increase in flask yield of the constructed strain VL-04. Next, we optimized the cofactor supply and demand balance by replacing ilvE with bcd (NADH-preferential) from Bacillus subtilis to construct the strain VL-06, which achieved a flask yield of 22.80 g/L, a further improvement of 25.8%. Subsequently, the fermentation conditions of VL-06 were optimized in a 5 L bioreactor with dual-phase oxygen-controlled fermentation. After optimization, the L-valine production reached 86.44 g/L in 26 h, with a glucose-to-acid conversion rate of 44.08% and a production intensity of 3.32 g/(L·h). This study not only shortens the time for L-valine production but also improves the economic efficiency, providing insights for similar fermentation processes employing dual-phase oxygen control.
Metabolic Engineering/methods* ; Escherichia coli/genetics* ; Valine/biosynthesis* ; Fermentation ; Bacillus subtilis/genetics*

Phenylpyruvic acid (PPA) is used as a food and feed additive and has a wide range of applications in the pharmaceutical, chemical and other fields. At present, PPA is mainly produced by chemical synthesis. With the green transformation of the manufacturing industry, biotransformation will be a good alternative for PPA production. The L-amino acid deaminase (PmiLAAD) from Proteus mirabilis has been widely studied for the production of PPA. However, the low yield limits its industrial production. To further enhance the production of PPA and better meet industrial demands, a more efficient synthesis method for PPA was established. In this study, PmiLAAD was heterologously expressed in Escherichia coli. Subsequently, a colorimetric reaction method was established to screen the strains with high PPA production. The semi-rational design of PmiLAAD was carried out, and the obtained triple-site mutant V18 (V437I/S93C/E417A) showed a 35% increase in catalytic activity compared with the wild type. Meanwhile, the effect of N-terminal truncation on the catalytic activity of the V18 mutant was investigated. After the optimization of the whole-cell conditions for the obtained mutant V18-N7, fed-batch conversion was carried out in a 5-L fermenter, and 44.13 g/L of PPA was synthesized with a conversion rate of 88%, which showed certain potential for industrial application. This study lays foundation for the industrial production of phenylpyruvic acid and also offers insights into the biosynthesis of other chemicals.
Escherichia coli/metabolism* ; Proteus mirabilis/genetics* ; Phenylpyruvic Acids/metabolism* ; Protein Engineering/methods* ; Recombinant Proteins/biosynthesis* ; Bacterial Proteins/metabolism*

L-tyrosine is one of the 20 amino acids that make up proteins and is an essential amino acid for mammals, often used as a nutritional supplement. The conventional methods for synthesizing L-tyrosine have some problems such as the production of many by-products, high requirements for production conditions, and environmental pollution. In this study, we designed and constructed a multi-enzyme cascade for the synthesis of L-tyrosine with alanine, glutamate, ammonium chloride, and phenol as substrates. Initially, the sources of glutamate oxidase, alanine aminotransferase, and tyrosine phenol lyase were screened and analyzed, which was followed by the identification of the rate-limiting enzyme in the reaction process. A colorimetric screening method was established, and the rate-limiting enzyme DbAlaA was engineered to enhance its activity by 40.0%. Subsequently, the reaction conditions, including temperature, pH, cell concentration, and surfactant and coenzyme dosages, were optimized. After optimization, the yield of L-tyrosine reached 9.93 g/L, with a alanine conversion rate of 54.90%. Finally, a feed-batch fermentation strategy was adopted, and the yield of L-tyrosine reached 56.07 g/L after 24 h, with a alanine conversion rate of 65.22%. This study provides a reference for the whole-cell catalytic synthesis of L-tyrosine and its industrialization.
Tyrosine/biosynthesis* ; Escherichia coli/metabolism* ; Tyrosine Phenol-Lyase/genetics* ; Multienzyme Complexes/metabolism* ; Fermentation

Objective: To investigate the factors affecting the development of non-proliferative diabetic retinopathy (NPDR) among patients with type 2 diabetic mellitus (T2DM), so as to provide insights into manangement of NPDR. Methods: T2DM patients without obvious eye discomfort at ages of 18 years and older admitted to Department of Endocrinology, Jining No. 1 People's Hospital during the period from December 2019 to May 2021 were enrolled. Participants' demographics, smoking, alcohol consumption, medical history of diabetes and use of medicines were collected, and the height, weight and blood pressure were measured. The levels of glycosylated hemoglobin (HbA1c), fasting blood glucose, blood C-peptide, lipid and creatinine were tested, and retinopathy was examined with a non-mydriatic fundus camera. The factors affecting the development of NPDR were identified among T2DM patients using a multivariable logistic regression model. Results: A total of 486 T2DM patients were enrolled, including 354 men (72.84%), with a median age of 48.00 (15.25) years, and median diabetes duration of 35.00 (104.25) months. The prevalence of NPDR was 19.34% among the participants. multivariable logistic regression analysis identified an educational level of senior high school and above (OR=0.546, 95%CI: 0.325-0.918), duration of diabetes (OR=1.008, 95%CI: 1.005-1.012), HbA1c (OR=1.183, 95%CI: 1.034-1.354) and use of non-sulfonylurea insulin secretagogues (OR=1.859, 95%CI: 1.082-3.196) as factors affecting the risk of NPDR among T2DM patients. Conclusion A high risk of NPDR is found among T2DM patients with a low educational level, long duration of diabetes, poor HbA1c control and use of non-sulfonylurea insulin secretagogues.

Objective:To investigate and analyze the clinical efficacy of salvage liver transplantation (SLT), rehepatectomy (RH), local ablation (LA), and prognostic risk factors in patients with postoperative recurrence of hepatocellular carcinoma.Methods:Clinical data of 145 patients with recurrent liver cancer in the 900th Hospital of the Joint Logistics Support Force of the People's Liberation Army from January 2005 to June 2018 were retrospectively collected. SLT group, RH group, and LA group included 25, 44, and 76 cases, respectively. Follow-up and statistics were recorded on the overall survival rate, relapse-free survival rate, and complications of the three groups of patients at 1, 2, and 3 years after surgery. Univariate and multivariate COX analyses were used to analyze the prognostic risk factors in patients with recurrent HCC.Results:The overall survival rates of 1, 2, and 3 years following surgery in the SLT, RH, and LA groups were 100.0%, 84.0%, 72.0%, 95.5%, 77.3%, 65.9%, 90.8%, 76.3%, and 63.2%, respectively, when the recurrence of liver cancer met the Milan criteria. The overall survival rate did not differ statistically between SLT and RH ( P = 0.303) or between RH and LA ( P = 0.152). There were statistically significant differences in recurrence-free survival between SLT and RH or RH and LA ( P = 0.046). There was no statistically significant difference in the incidence of complications between SLT and RH or RH and LA ( P > 0.017). Age > 65 years was an independent risk factor affecting the overall survival rate in patients with recurrent HCC. Age > 65 years and recurrence time < 24 months were independent risk factors affecting the recurrence-free survival rate in patients with recurrent HCC. Conclusion:SLT is the best treatment option when the recurrence of HCC meets Milan's criteria. RH and LA are the appropriate treatment plans for recurrent HCC when the liver source is limited.

Objective:To characterize the histopathological subtypes and their clinicopathological parameters of gender and onset age by common, rare and sparse primary esophageal malignant tumors (PEMT).Methods:A total of 272 437 patients with PEMT were enrolled in this study, and all of the patients were received radical surgery. The clinicopathological information of the patients was obtained from the database established by the State Key Laboratory of Esophageal Cancer Prevention & Treatment from September 1973 to December 2020, which included the clinical treatment, pathological diagnosis and follow-up information of esophagus and gastric cardia cancers. All patients were diagnosed and classified by the criteria of esophageal tumor histopathological diagnosis and classification (2019) of the World Health Organization (WHO). The esophageal tumors, which were not included in the WHO classification, were analyzed separately according to the postoperative pathological diagnosis. The χ 2 test was performed by the SPSS 25.0 software on count data, and the test standard α=0.05. Results:A total of 32 histopathological types were identified in the enrolled PEMT patients, of which 10 subtypes were not included in the WHO classification. According to the frequency, PEMT were divided into common (esophageal squamous cell carcinoma, ESCC, accounting for 97.1%), rare (esophageal adenocarcinoma, EAC, accounting for 2.3%) and sparse (mainly esophageal small cell carcinoma, malignant melanoma, etc., accounting for 0.6%). All the common, rare, and sparse types occurred predominantly in male patients, and the gender difference of rare type was most significant (EAC, male∶ female, 2.67∶1), followed with common type (ESCC, male∶ female, 1.78∶1) and sparse type (male∶ female, 1.71∶1). The common type (ESCC) mainly occurred in the middle thoracic segment (65.2%), while the rare type (EAC) mainly occurred in the lower thoracic segment (56.8%). Among the sparse type, malignant melanoma and malignant fibrous histiocytoma were both predominantly located in the lower thoracic segment (51.7%, 66.7%), and the others were mainly in the middle thoracic segment.Conclusion:ESCC is the most common type among the 32 histopathological types of PEMT, followed by EAC as the rare type, and esophageal small cell carcinoma and malignant melanoma as the major sparse type, and all of which are mainly occur in male patients. The common type of ESCC mainly occur in the middle thoracic segment, while the rare type of EAC mainly in the lower thoracic segment. The mainly sparse type of malignant melanoma and malignant fibrous histiocytoma predominately occur in the lower thoracic segment, and the remaining sparse types mainly occur in the middle thoracic segment.

Cyclin-dependent kinase 10 (CDK10) function as a tumor suppressor gene through regulating cell cycle interacting with transcription factor Ets2.Studies demonstrate that the downregulation of CDK10 expression occurs in multiple cancer types,indicating a potential application of CDK10 as a molecular diagnostic marker as well as therapeutic target.

OBJECTIVETo study the expression of peroxisome proliferators-activated receptor (PPAR) in human glioma tissue and its influence on tumor growth.

METHODSExpression of PPAR mRNA in glioma tissue was determined by real-time reverse transcription polymerase chain reaction (RT-PCR). Subsequently, MTT (3-(4, 5)-dimethylthiahiazo(-z-y1)-3, 5-di-phenytetrazoliumromide) assay, flow cytometry, reactive oxygen species assay kit and Western blotting were used to assay U87 cells with agonist activity of PPAR.

RESULTSThe data demonstrated that the expression of PPAR in glioma was low and negatively correlated with its pathological grade. Activation of PPAR suppresses tumor cell proliferation, delays the cell cycle at G1 phrase, and induces apoptosis and accumulation of reactive oxygen species (ROS) in U87 cells.

CONCLUSIONThe expression of PPAR mRNA in human glioma was low. PPAR protein plays a critical role in the progression of glioma via the PPAR signal pathway.

Apoptosis ; Cell Cycle Checkpoints ; Cell Line, Tumor ; Cell Proliferation ; Gene Expression ; Glioma ; genetics ; metabolism ; physiopathology ; Humans ; PPAR alpha ; genetics ; metabolism ; Signal Transduction

OBJECTIVETo study the expression of FOS protein in human glioma tissues and its effect on tumor growth.

METHODSFOS protein expression in glioma tissues was determined with immunohistochemical (IHC) staining. Subsequently, 3-(4,5)-dimethylthiahiazo(-z-y1)-3,5-diphenytetrazoliumromide (MTT) assay, flow cytometry, transwell invasion and Western blotting were used to assay U87 and U251 cells with reduced FOS expression.

RESULTSThe expression of FOS in glioma was increased and strongly correlated with its pathological grade. Abrogating expression of FOS has suppressed proliferation and invasion, and delayed cell cycle at G1 phrase for both U87 and U251 cells.

CONCLUSIONThe expression of FOS protein in human glioma was strong. FOS protein probably plays a critical role in the progression of gliomas.

Cell Line, Tumor ; Cell Movement ; genetics ; Cell Proliferation ; Cyclin D1 ; genetics ; metabolism ; Gene Expression ; Glioma ; genetics ; metabolism ; pathology ; Humans ; Matrix Metalloproteinase 9 ; genetics ; metabolism ; Neoplasm Grading ; Proto-Oncogene Proteins c-fos ; genetics ; metabolism ; RNA Interference