γ-aminobutyric acid can be produced by a one-step enzymatic reaction catalyzed by glutamic acid decarboxylase. The reaction system is simple and environmentally friendly. However, the majority of GAD enzymes catalyze the reaction under acidic pH at a relatively narrow range. Thus, inorganic salts are usually needed to maintain the optimal catalytic environment, which adds additional components to the reaction system. In addition, the pH of solution will gradually rise along with the production of γ-aminobutyric acid, which is not conducive for GAD to function continuously. In this study, we cloned the glutamate decarboxylase LpGAD from a Lactobacillus plantarum capable of efficiently producing γ-aminobutyric acid, and rationally engineered the catalytic pH range of LpGAD based on surface charge. A triple point mutant LpGAD^{S24R/D88R/Y309K} was obtained from different combinations of 9 point mutations. The enzyme activity at pH 6.0 was 1.68 times of that of the wild type, suggesting the catalytic pH range of the mutant was widened, and the possible mechanism underpinning this increase was discussed through kinetic simulation. Furthermore, we overexpressed the Lpgad and Lpgad^{S24R/D88R/Y309K} genes in Corynebacterium glutamicum E01 and optimized the transformation conditions. An optimized whole cell transformation process was conducted under 40 ℃, cell mass (OD₆₀₀) 20, 100 g/L l-glutamic acid substrate and 100 μmol/L pyridoxal 5-phosphate. The γ-aminobutyric acid titer of the recombinant strain reached 402.8 g/L in a fed-batch reaction carried out in a 5 L fermenter without adjusting pH, which was 1.63 times higher than that of the control. This study expanded the catalytic pH range of and increased the enzyme activity of LpGAD. The improved production efficiency of γ-aminobutyric acid may facilitate its large-scale production.
Glutamate Decarboxylase/genetics* ; Lactobacillus plantarum/genetics* ; Catalysis ; gamma-Aminobutyric Acid ; Hydrogen-Ion Concentration ; Glutamic Acid

Malignant mesothelioma is a highly malignant disease that most often occurs in the pleural cavity, followed by the peritoneum and pericardium. Malignant peritoneal mesothelioma (MPM) accounts for 10%-15% of all mesothelioma. The most important risk factor for MPM is exposure to asbestos. MPM has no specific clinical symptoms, imaging and histopathology are critical for the diagnosis. There are currently no generally accepted guidelines for curative treatment of MPM. The patient mainly presented with abdominal pain, abdominal distension and discomfort. Due to extensive omentum metastasis, no further surgical treatment was performed. Pemetrexed combined with cisplatin chemotherapy was given for 2 cycles, and the patient is still alive.
Humans ; Mesothelioma, Malignant/drug therapy* ; Mesothelioma/diagnosis* ; Pemetrexed/therapeutic use* ; Cisplatin/therapeutic use* ; Peritoneal Neoplasms/diagnosis* ; Pleural Neoplasms ; Lung Neoplasms/drug therapy*

OBJECTIVES: To study new biomarkers for the early diagnosis of retinopathy of prematurity (ROP) by analyzing the differences in blood metabolites based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) and metabolomics. METHODS: Dried blood spots were collected from 21 infants with ROP (ROP group) and 21 infants without ROP (non-ROP group) who were hospitalized in the Sixth Affiliated Hospital of Sun Yat-sen University from January 2013 to December 2016. LC-MS/MS was used to measure the metabolites, and orthogonal partial least squares-discriminant analysis was used to search for differentially expressed metabolites and biomarkers. RESULTS: There was a significant difference in blood metabolic profiles between the ROP and non-ROP groups. The pattern recognition analysis, Score-plot, and weight analysis obtained 10 amino acids with a relatively large difference. Further statistical analysis showed that the ROP group had significant increases in blood levels of glutamic acid, leucine, aspartic acid, ornithine, and glycine compared with the non-ROP group (P<0.05). The receiver operating characteristic curve analysis showed that glutamic acid and ornithine had the highest value in diagnosing ROP. CONCLUSIONS Blood metabolites in preterm infants with ROP are different from those without ROP. Glutamic acid and ornithine are the metabolic markers for diagnosing ROP. LC-MS/MS combined with metabolomics analysis has a potential application value in the early identification and diagnosis of ROP.
Infant, Newborn ; Infant ; Humans ; Tandem Mass Spectrometry ; Infant, Premature ; Chromatography, Liquid ; Retinopathy of Prematurity/diagnosis* ; Glutamic Acid ; Ornithine

Objective: To explore the relationship between extracellular enzymes activity and virulence of Candida glabrata clinical isolates based on the infection model of Galleria mellonella larvae. Methods: Using experimental research methods, 71 strains of non-repetitive Candida glabrata were collected from Qinghai Provincial People's Hospital from June 2021 to January 2022. Bovine serum protein agar medium, egg yolk agar medium, sheep blood agar medium, Tween-80 agar medium and triglyceride agar medium were used to detect the aspartyl protease activity, phospholipase activity, hemolysis activity, esterase activity and lipase activity of Candida glabrata. Median lethal concentration (LC₅₀) was calculated by using 1.25×10⁸ CFU/ml,2.50×10⁸ CFU/ml,3.75×10⁸ CFU/ml,5.00×10⁸ CFU/ml suspension of Candida glabrata ATCC2001 to infect Galleria mellonella larvae. Histopathological and etiological analysis was performed to determine whether the infection model was successfully established. The clinical isolates of Candida glabrata were configured to infect Galleria mellonella larvae with LC₅₀ concentration to detect the pathogenicity of Galleria mellonella larvae.Spearman test or Pearson test were used to analyze the correlation between the extracellular enzyme activity of Candida glabrata clinical isolates and the pathogenicity of Galleria mellonella larvae. Results: 71 strains of Candida glabrata isolated clinically were detected to have low hemolytic activity after 2 days of culture. Aspartyl protease was detected after 4 days of culture, among which 7 strains (9.86%), 19 strains (26.76%) and 45 strains (63.38%) showed low, medium and high aspartyl protease activity. After 7 days of culture, 71 strains did not detect phospholipase, esterase and lipase activities. Candida glabrata on Galleria mellonella larvae of LC₅₀=2.5×10⁸ CFU/ml Fungal spore were found in the intestinal tissue pathological section of Galleria mellonella larvae in the experimental group, and Candida glabrata was identified by the microbial Mass Spectrometry after culture, while no fungi were found in the pathological section and culture of the control group. Spearman test shows that, there was a linear positive correlation between aspartyl protease activity and the survival rate of Galleria mellonella larvae (r = 0.73, P<0.01), the difference was statistically significant.Pearson test shows that, there was no significant linear relationship between hemolytic activity and survival rate of Galleria mellonella larvae (r = 0.16, P = 0.34), the difference was not statistically significant. Conclusion: The clinical isolates of Candida glabrata in this study had aspartyl protease activity and low hemolytic activity, but no phospholipase, esterase and lipase activity. The activity of aspartyl aspartyl protease of Candida glabrata was positively correlated with the pathogenicity of Galleria mellonella larvae.
Animals ; Sheep ; Larva/microbiology* ; Virulence ; Candida glabrata ; Agar ; Moths/microbiology* ; Esterases ; Aspartic Acid Proteases ; Lipase

Citric Acid Cycle ; Citric Acid ; Malates/metabolism* ; Citrates/metabolism* ; Aspartic Acid/metabolism*

BACKGROUND: The brain is a common metastatic site in patients with non-small cell lung cancer (NSCLC), resulting in a relatively poor prognosis. Systemic therapy with epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs) is recommended as the first-line treatment for EGFR -mutated, advanced NSCLC patients. However, intracranial activity varies in different drugs. Thus, brain metastasis (BM) should be considered when choosing the treatment regimens. We conducted this network meta-analysis to explore the optimal first-line therapeutic schedule for advanced EGFR -mutated NSCLC patients with different BM statuses. METHODS: Randomized controlled trials focusing on EGFR-TKIs (alone or in combination) in advanced and EGFR -mutant NSCLC patients, who have not received systematic treatment, were systematically searched up to December 2021. We extracted and analyzed progression-free survival (PFS) and overall survival (OS). A network meta-analysis was performed with the Bayesian statistical model to determine the survival outcomes of all included therapy regimens using the R software. Hazard ratios (HRs) and 95% confidence intervals (CIs) were used to compare intervention measures, and overall rankings of therapies were estimated under the Bayesian framework. RESULTS: This analysis included 17 RCTs with 5077 patients and 12 therapies, including osimertinib + bevacizumab, aumolertinib, osimertinib, afatinib, dacomitinib, standards of care (SoC, including gefitinib, erlotinib, or icotinib), SoC + apatinib, SoC + bevacizumab, SoC + ramucirumab, SoC + pemetrexed based chemotherapy (PbCT), PbCT, and pemetrexed free chemotherapy (PfCT). For patients with BM, SoC + PbCT improved PFS compared with SoC (HR = 0.40, 95% CI: 0.17-0.95), and osimertinib + bevacizumab was most likely to rank first in PFS, with a cumulative probability of 34.5%, followed by aumolertinib, with a cumulative probability of 28.3%. For patients without BM, osimertinib + bevacizumab, osimertinib, aumolertinib, SoC + PbCT, dacomitinib, SoC + ramucirumab, SoC + bevacizumab, and afatinib showed superior efficacy compared with SoC (HR = 0.43, 95% CI: 0.20-0.90; HR = 0.46, 95% CI: 0.31-0.68; HR = 0.51, 95% CI: 0.34-0.77; HR = 0.50, 95% CI: 0.38-0.66; HR = 0.62, 95% CI: 0.43-0.89; HR = 0.64, 95% CI: 0.44-0.94; HR = 0.61, 95% CI: 0.48-0.76; HR = 0.71, 95% CI: 0.50-1.00), PbCT (HR = 0.29, 95% CI: 0.11-0.74; HR = 0.31, 95% CI: 0.15-0.62; HR = 0.34, 95% CI: 0.17-0.69; HR = 0.34, 95% CI: 0.18-0.64; HR = 0.42, 95% CI: 0.21-0.82; HR = 0.43, 95% CI: 0.22-0.87; HR = 0.41, 95% CI: 0.22-0.74; HR = 0.48, 95% CI: 0.31-0.75), and PfCT (HR = 0.14, 95% CI: 0.06-0.32; HR = 0.15, 95% CI: 0.09-0.26; HR = 0.17, 95% CI: 0.09-0.29; HR = 0.16, 95% CI: 0.10-0.26; HR = 0.20, 95% CI: 0.12-0.35; HR = 0.21, 95% CI: 0.12-0.39; HR = 0.20, 95% CI: 0.12-0.31; HR = 0.23, 95% CI: 0.16-0.34) in terms of PFS. And, SoC + apatinib showed relatively superior PFS when compared with PbCT (HR = 0.44, 95% CI: 0.22-0.92) and PfCT (HR = 0.21, 95% CI: 0.12-0.39), but similar PFS to SoC (HR = 0.65, 95% CI: 0.42-1.03). No statistical differences were observed for PFS in patients without BM between PbCT and SoC (HR = 1.49, 95% CI: 0.84-2.64), but both showed favorable PFS when compared with PfCT (PfCT vs. SoC, HR = 3.09, 95% CI: 2.06-4.55; PbCT vs. PfCT, HR = 0.14, 95% CI: 0.06-0.32). For patients without BM, osimertinib + bevacizumab was most likely to rank the first, with cumulative probabilities of 47.1%. For OS, SoC + PbCT was most likely to rank first in patients with and without BM, with cumulative probabilities of 46.8%, and 37.3%, respectively. CONCLUSION Osimertinib + bevacizumab is most likely to rank first in PFS in advanced EGFR -mutated NSCLC patients with or without BM, and SoC + PbCT is most likely to rank first in OS.
Humans ; Carcinoma, Non-Small-Cell Lung/metabolism* ; Afatinib/therapeutic use* ; Lung Neoplasms/metabolism* ; Bevacizumab/therapeutic use* ; Bayes Theorem ; Network Meta-Analysis ; Protein Kinase Inhibitors/therapeutic use* ; Pemetrexed/therapeutic use* ; ErbB Receptors/genetics* ; Brain Neoplasms/genetics* ; Mutation/genetics*

The purpose of this study was to investigate the effect of glutamate and its ionotropic receptor agonists on the response to acute hypoxia in rat carotid body in vitro. Briefly, after SD rats were anesthetized and decapitated, the bilateral carotid bifurcations were rapidly isolated. Then bifurcation was placed into a recording chamber perfused with 95% O₂-5% CO₂ saturated Kreb's solution. The carotid body-sinus nerve complex was dissected, and the carotid sinus nerve discharge was recorded using a suction electrode. To detect the response of carotid body to acute hypoxia, the chamber was perfused with 5% O₂-5% CO₂-90% N₂ saturated Kreb's solution for a period of 100 s at an interval of 15 min. To observe the effect of glutamate, ionotropic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor agonist AMPA or N-methyl-D-aspartate (NMDA) receptor agonist NMDA on the response to acute hypoxia in rat carotid body, the chamber was perfused with 5% O₂-5% CO₂-90% N₂ saturated Kreb's solution containing the corresponding reagent. The results showed that glutamate (20 μmol/L), AMPA (5 μmol/L) or NMDA (10 μmol/L) inhibited the acute hypoxia-induced enhancement of carotid sinus nerve activity, and these inhibitory effects were dose-dependent. In summary, the activation of glutamate ionotropic receptors appears to exert an inhibitory effect on the response to acute hypoxia in carotid body of rats.
Rats ; Animals ; Glutamic Acid/pharmacology* ; alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid/pharmacology* ; N-Methylaspartate/pharmacology* ; Carotid Body ; Rats, Sprague-Dawley ; Carbon Dioxide ; Receptors, N-Methyl-D-Aspartate ; Receptors, AMPA ; Hypoxia

This study used m-chloropheniperazine(MCPP) and chronic unforeseeable mild stress(CUMS) to induce the rat models of anxiety and depression, respectively. The behaviors of rats were observed by the open field test(OFT), light-dark exploration test(LDE), tail suspension test(TST), and forced swimming test(FST), and the antidepressant and anxiolytic effects of agarwood essential oil(AEO), agarwood fragrant powder(AFP), and agarwood line incense(ALI) were explored. The enzyme-linked immunosorbent assay(ELISA) was used to determine the levels of 5-hydroxytryptamine(5-HT), glutamic acid(Glu), and γ-aminobutyric acid(GABA_A) in the hippocampal area. The Western blot assay was used to determine the protein expression levels of glutamate receptor 1(GluR1) and vesicular glutamate transporter type 1(VGluT1), exploring the anxiolytic and antidepressant mechanism of agarwood inhalation. The results showed that compared with the anxiety model group, the AEO, AFP, and ALI groups decreased the total distance(P<0.05), decreased the velocity of movements(P<0.05), prolonged the immobile time(P<0.05), and reduced the distance and velocity of the rat model of anxiety in the dark box(P<0.05). Compared with the depression model group, the AEO, AFP, and ALI groups increased the total distance and average velocity(P<0.05), reduced the immobile time(P<0.05), and reduced the forced swimming and tail suspension time(P<0.05). In terms of transmitter regulation, the AEO, AFP, and ALI groups decreased the level of Glu in the rat model of anxiety(P<0.05) and increased the levels of GABA_A and 5-HT(P<0.05), while the AEO, AFP, and ALI groups all increased the level of 5-HT in the rat model of depression(P<0.05) and decreased the levels of GABA_A and Glu(P<0.05). At the same time, the AEO, AFP, and ALI groups all increased the protein expression levels of GluR1 and VGluT1 in the hippocampus of the rat models of anxiety and depression(P<0.05). In conclusion, AEO, AFP, and ALI exert anxiolytic and antidepressant effects, and the mechanism might be related to the regulation of the neurotransmitter and the protein expression of GluR1 and VGluT1 in the hippocampus.
Animals ; Rats ; Anti-Anxiety Agents ; Serotonin ; alpha-Fetoproteins ; Antidepressive Agents ; Glutamic Acid ; gamma-Aminobutyric Acid

L-glutamic acid is the world's largest bulk amino acid product that is widely used in the food, pharmaceutical and chemical industries. Using Corynebacterium glutamicum G01 as the starting strain, the fermentation by-product alanine content was firstly reduced by knocking out the gene encoding alanine aminotransferase (alaT), a major by-product related to alanine synthesis. Secondly, since the α-ketoglutarate node carbon flow plays an important role in glutamate synthesis, the ribosome-binding site (RBS) sequence optimization was used to reduce the activity of α-ketoglutarate dehydrogenase and enhance the glutamate anabolic flow. The endogenous conversion of α-ketoglutarate to glutamate was also enhanced by screening different glutamate dehydrogenase. Subsequently, the glutamate transporter was rationally desgined to improve the glutamate efflux capacity. Finally, the fermentation conditions of the strain constructed using the above strategy were optimized in 5 L fermenters by a gradient temperature increase combined with a batch replenishment strategy. The glutamic acid production reached (135.33±4.68) g/L, which was 41.2% higher than that of the original strain (96.53±2.32) g/L. The yield was 55.8%, which was 11.6% higher than that of the original strain (44.2%). The combined strategy improved the titer and the yield of glutamic acid, which provides a reference for the metabolic modification of glutamic acid producing strains.
Glutamic Acid ; Corynebacterium glutamicum/genetics* ; Ketoglutaric Acids ; Metabolic Engineering ; Alanine

Aminopeptidase A (Pep A) is a metal-dependent enzyme that specifically hydrolyze peptides with the N-terminal amino acids glutamic acid (Glu) and aspartic acid (Asp). A possible application of PepA is the hydrolysis of Glu/Asp-rich food proteins such as wheat gluten and casein, increasing the flavor and solubility of food protein. In the present study, the gene encoding a Pep A from Lactococcus lactis ssp. lactis IL1403 was synthesized and introduced into Pichia pastoris GS115 (His4). Lc-Pep A was successfully expressed and secreted to the culture medium, followed by identification and purification to homogeneity. Characteristics study demonstrated that Lc-Pep A could specifically hydrolyze the substrates Glu-pNA and Asp-pNA with similar catalytic activity, and this was further confirmed by the kinetics parameters measured. Additionally, Lc-Pep A showed a broad thermostability and pH stability with an optimum temperature of 60 ℃ and an optimum pH of 8.0. The enzyme activity of Lc-Pep A was activated by metal ions Co²⁺, Mn²⁺, and Zn²⁺ but was strongly inhibited by Ni²⁺and Cu²⁺. The routine proteinase inhibitor had no effect on the activity of Lc-Pep A. However, Lc-Pep A was strongly inhibited by the metallopeptidase inhibitor, EDTA, and disulfide bond-reducing agents. The study may facilitate production and application of Lc-Pep A.
Glutamyl Aminopeptidase ; Lactococcus lactis/genetics* ; Biological Transport ; Culture Media ; Glutamic Acid