Cognitive Function and Medication Adherence in Older Adults With H-Type Hypertension: The Mediating Effect of Metamemory.

PURPOSE: Medication adherence in adults with H-type hypertension plays a crucial role in lowering blood pressure and treating complications. Cognitive function has been identified as a significant influencing factor for medication adherence, whereas excessive levels of homocysteine can impair cognitive function. Metamemory, which is influenced by cognitive function, also affects medication adherence. However, the complex relationship among these factors remains poorly understood among adults with H-type hypertension. Therefore, we hypothesize that metamemory serves as a mediator for the impact of cognitive function on medication adherence. METHOD: A total of 232 adults with H-type hypertension were enrolled to provide cognitive function scores, metamemory scores, and medication adherence rates. RESULTS: A pairwise correlation exists among cognitive function, metamemory, and medication adherence. Metamemory partially mediates (57.5%) the relationship between cognitive function and medication adherence. CONCLUSION: Our findings suggest that interventions targeting improvements in metamemory may enhance medication adherence among individuals with H-type hypertension. [Journal of Gerontological Nursing, 50(6), 44-52.].

Efficacy of botanical lozenges in the treatment of chronic pharyngitis: a randomized controlled trial.

Background: In clinical practice, antibiotics and/or inhaled or oral hormone preparations are the first line of treatment for chronic pharyngitis. However, this therapeutic regimen is not satisfactory enough. At present, medicinal plants as dietary supplements or functional foods are widely recognized for the treatment and prevention of different diseases. Purpose: This study aimed to evaluate the efficacy of the botanical lozenge made from several medicinal plant extracts in the treatment of chronic pharyngitis and its effects on patients' illness perception and adherence to treatment. Methods: Patients with chronic pharyngitis were randomly assigned to the experimental group (n = 52) or the control group (n = 51). Patients were given botanical lozenges prepared from the extracts of medicinal plants such as Siraitia grosvenorii (Swingle) C. Jeffrey ex A.M.Lu and Zhi Y. Zhang [Cucurbitaceae; Siraitiae fructus], Lonicera japonica Thunb [Caprifoliaceae; Lonicerae japonicae flos], Platycodon grandiflorus (Jacq.) A. DC [Campanulaceae; Platycodon radix], and Glycyrrhiza uralensis Fisch. ex DC [Fabaceae; Glycyrrhizae radix et rhizoma] or placebos made of starch for 15 days. The improvement of pharyngeal symptoms and signs, illness perception, and adherence to treatment were evaluated at the end of the intervention. Results: The total score of pharyngeal symptoms of patients in the experimental group (3.33 ± 2.33) was significantly lower than that in the control group (5.20 ± 2.93) (p < 0.01). In comparison to the control group (3.43 ± 1.43), the total pharyngeal signs score of patients in the experimental group (2.69 ± 1.59) was considerably lower (p < 0.01). The improvement rates of pharyngeal itching, dry throat, pharyngeal foreign body sensation, aggravation due to excessive speaking, and congestion of pharyngeal mucosa in the experimental group were 73.81%, 67.50%, 67.57%, 65.22% and 44%, respectively, which were significantly higher than those in the control group (p < 0.05). In addition, patients taking botanical lozenges had better illness perception and adherence to treatment than those taking placebos (p < 0.05). Patients with low adherence to treatment showed less personal control, concerns, and understanding of chronic pharyngitis (p < 0.05). Conclusion: Botanical lozenges not only aided patients in recovering from chronic pharyngitis but also improved their positive perceptions of the disease, which helped them adhere to their treatment regimen. Clinical Trial Registration: [https://www.chictr.org.cn/], identifier [ChiCTR2200062139].

Xylo-oligosaccharides improve functional constipation by targeted enrichment of Bifidobacterium.

Functional constipation (FC) has a negative impact on patients' quality of life. We hypothesized that dietary supplementation with xylo-oligosaccharides (XOS) or fructo-oligosaccharides (FOS) would improve constipation symptoms by influencing the gut microbiota. A randomized double-blind controlled trial was conducted in FC patients. Patients were randomly divided into 6 groups and given a dietary supplement containing XOS at doses of 3, 5, or 10 g/day, FOS at doses of 10 and 20 g/day, or placebo at 5 g/day for one month. We compared improvements in gastrointestinal function after the intervention using the Bristol Stool Form Scale (BSFS), Cleveland Clinic Constipation Score (CCCS), and Quality of Life Scale for Patients with Constipation (PAC-QoL). 16S rRNA sequencing was used to assess changes in the structure of the gut microbiota. Changes in individual bacteria had significant effects in reducing gastrointestinal symptoms during the intervention, even though the flora structure remained unchanged from baseline. Compared to FOS, XOS enriched Bifidobacterium at a lower dose, and patients receiving XOS supplementation showed significant improvements in constipation symptoms without side effects such as diarrhea and flatulence.

Mediating effect of gastrointestinal symptoms on dietary behavior and quality of life in Chinese adults with chronic gastritis-a cross-sectional study.

Background: Chronic gastritis is accompanied by varying degrees of gastrointestinal symptoms, which affect people's quality of life. The association between dietary behaviors and gastrointestinal symptoms of patients with chronic gastritis has been proved recently. However, no studies have been conducted to investigate the relationship between dietary behaviors, gastrointestinal symptoms, and quality of life. Methods: A cross-sectional survey of 176 patients diagnosed with chronic gastritis aged 18 to 65 years, comprising their information on demographic characteristics, dietary behaviors, gastrointestinal symptoms, and quality of life, was collected. A descriptive analysis and a correlation matrix were used to illuminate the characteristics of the subjects and bivariate correlation, respectively. The mediation model was analyzed using the PROCESS macros for SPSS. Results: Demographic characteristics were found to influence the symptoms, dietary behaviors, and quality of life of chronic gastritis patients; in particular, students categorized by occupation had higher levels of gastrointestinal symptoms and lower levels of quality of life and dietary behavior. The study variables were all pound related. We found that gastrointestinal symptoms played a partial mediating role between dietary behavior and both the physical components summary and mental components summary, and the ratios of mediating effects to the total effect on the physical components summary and mental components summary were 23.5% and 21.5%, respectively. Conclusion: Our survey discovered that dietary behavior, gastrointestinal symptoms, and quality of life were all pairwise related. The effect of dietary behavior on quality of life was partially mediated by gastrointestinal symptoms. These results may provide a novel perspective for medical staff in improving the quality of life of patients with chronic gastritis.

Effects of different n-6/n-3 polyunsaturated fatty acids ratios on lipid metabolism in patients with hyperlipidemia: a randomized controlled clinical trial.

Background and aims: Intake of n-3 polyunsaturated fatty acids (PUFA) is helpful for cardiometabolic health. It improves lipid metabolism, and increasing n-3 PUFA is often considered beneficial. However, the role of n-6/n-3 in the regulation of lipid metabolism has been much debated. Therefore, this study was performed on the effect of different proportions of n-6/n-3 diet on lipid metabolism, and quality of life in patients with hyperlipidemia, aiming to explore appropriate proportions of n-6/n-3 to provide the theoretical basis for the development and application of nutritional blended oil in the future. Methods: These 75 participants were randomized and assigned into three groups, which received dietary oil with high n-6/n-3 PUFA ratios (HP group: n-6/n-3 = 7.5/1), dietary oil with middle n-6/n-3 PUFA ratios (MP group: n-6/n-3 = 2.5/1) or low n-6/n-3 PUFA ratios (LP group: n-6/n-3 = 1/2.5). All patients received dietary guidance and health education were monitored for hyperlipidemia. Anthropometric, lipid and blood glucose parameters and quality of life were assessed at baseline and 60 days after intervention. Result: After 60 days, high-density lipoprotein cholesterol (HDL-c) level was increased (p = 0.029) and Total cholesterol (TC) level was decreased (p = 0.003) in the MP group. In the LP group, TC level was decreased (p = 0.001), TG level was decreased (p = 0.001), but HDL-c level was not significantly increased. At the end of intervention, quality of life' score was improved in both MP and LP groups (p = 0.037). Conclusion: Decreasing the intake of edible oil n-6/n-3 ratio can improve blood lipids and quality of life. This is significant for the prevention of cardiovascular disease (CVD). It is also essential to note that an excessive reduction of the n-6/n-3 ratio does not further improve the blood lipid metabolism. In addition, the application of perilla oil in nutritional blended oil has particular significance. Clinical trial registration: https://www.chictr.org.cn/indexEN.html, identifier ChiCTR-2300068198.

Pulmonary microbiota signatures adjacent to adenocarcinoma, squamous cell carcinoma and benign lesion.

Introduction: The occurrence and progression of lung cancer are influenced by pulmonary microbiota, yet the relationship between changes in the pulmonary microbiota and lung cancer remains unclear. Methods: To investigate the correlation between pulmonary microbiota and the signature of lung lesions, we analyzed the microbial composition at sites adjacent to the stage 1 adenocarcinoma, squamous carcinoma and benign lesion tissues in 49 patients by using 16S ribosomal RNA gene sequencing. We then conducted Linear discriminant analysis, receiver operating characteristic (ROC) curve analysis and PICRUSt prediction based on 16S sequencing results. Results: Overall, the microbiota composition at sites close to lung lesions showed significant differences between different lesion types. Based on the results of LEfSe analysis, Ralstonia, Acinetobacter and Microbacterium are the dominant genera of lung adenocarcinoma (LUAD), lung squamous carcinoma (LUSC) and benign lesions (BENL), respectively. Furthermore, we determined the diagnostic value of the abundance ratio of Ralstonia to Acinetobacter in adenocarcinoma patients through ROC curve analysis. The PICRUSt analysis revealed 15 remarkably different metabolic pathways in these lesion types. In LUAD patients, the increase of the pathway associated with xenobiotic biodegradation may be due to the continuous proliferation of microbe with degradation ability of xenobiotics, which implied that LUAD patients are often exposed to harmful environment. Discussion: The abundance of Ralstonia was related to the development of lung cancer. By measuring the abundance of microbiota in diseased tissues, we can distinguish between different types of lesions. The differences in pulmonary microbiota between lesion types are significant in understanding the occurrence and development of lung lesions.

Combined treatment with glucosamine and chondroitin sulfate improves rheumatoid arthritis in rats by regulating the gut microbiota.

BACKGROUND: To investigate the ameliorative effects of glucosamine (GS), chondroitin sulphate (CS) and glucosamine plus chondroitin sulphate (GC) on rheumatoid arthritis (RA) in rats, and to explore the mechanism of GS, CS and GC in improving RA based on the gut microbiota. METHODS: RA rat models were effectively developed 14 days after CFA injection, and then garaged with GS, CS and GC. Body weight and paw volume of rats were monitored at multiple time points at the beginning of CFA injection. Until D36, serum and ankle tissue specimens were used to measure levels of circulating inflammatory factors (TNF-α, IL-1ß, MMP-3, NO and PGE2) and local inflammatory indicators (TLR-4 and NF-κB). On D18, D25, and D36, intergroup gut microbiota was compared using 16S rRNA gene sequencing and bioinformatics analysis. We also performed the correlation analysis of gut bacteria, joint swelling and inflammatory indicators. RESULTS: GC, rather than GS and CS, could reduce right paw volumes, levels of TLR-4 and NF-κB in synovial tissues. In addition, enriched genera in RA model rats screened out by LEfSe analysis could be inhibited by GC intervention, including potential LPS-producing bacteria (Enterobacter, Bacteroides, Erysipelotrichaceae_unclassified and Erysipelotrichaceae_uncultured) and some other opportunistic pathogens (Esherichia_Shigella, Nosocomiicoccus, NK4A214_group, Odoribacter, Corynebacterium and Candidatus_Saccharimonas.etc.) that positively correlated with pro-inflammatory cytokines, right paw volume, and pathology scores. Furthermore, the gut microbiota dysbiosis was observed to recover before alleviating joint swelling after interventions. CONCLUSIONS: GC could inhibit potential LPS-producing bacteria and the activation of TLR-4/NF-κB pathway in RA rats, thus alleviating RA-induced joint injury.

Precise Photothermal Treatment of Methicillin-Resistant S. aureus Infection via Phage Lysin-Cell Binding Domain-Modified Gold Nanosheets.

The increasing spread of antibiotic resistance in bacterial pathogens poses a huge threat to global human health. Precise targeting of bacterial pathogens while avoiding collateral damage to healthy tissues has become the overriding goal for bacterial infection treatment. Inspired by the host specificity of bacteriophages, a biomimetic intelligent platform was designed for highly precise photothermal treatment herein. As proof-of-concept, the lysin cell-binding domain (CBD) from a newly discovered virulent methicillin-resistant S. aureus (MRSA) phage Z was applied to the functionalization of gold nanosheets. Our results demonstrated that the bionanocomposite gold particles (Au@PEG-CBDz) could be effectively delivered directly to MRSA and kill them effectively under near infrared irradiation in vitro, while displaying good in vivo biocompatibility. This work is the first to report the combination of phage lysin navigatory function with photothermal effect-induced bactericidal activity from Au nanosheets, providing a novel therapeutic mode for the precision treatment of antibiotic-resistant bacterial infections.

White common bean extract remodels the gut microbiota and ameliorates type 2 diabetes and its complications: A randomized double-blinded placebo-controlled trial.

Objective: Excessive carbohydrate intake is a high risk factor for increased morbidity of type 2 diabetes (T2D). A novel regimen for the dietary care of diabetes that consists of a highly active α-amylase inhibitor derived from white common bean extract (WCBE) and sufficient carbohydrates intake was applied to attenuate T2D and its complications. Furthermore, the role of gut microbiota in this remission was also investigated. Methods: We conducted a 4-month randomized double-blinded placebo-controlled trial. During the intense intervention period, ninety subjects were randomly assigned to the control group (Group C) and WCBE group (Group W). Subjects in Group C were supplemented with 1.5 g of maltodextrin as a placebo. Subjects in Group W took 1.5 g of WCBE half an hour before a meal. Fifty-five participants continued the maintenance intervention receiving the previous dietary intervention whereas less frequent follow-up. The variation in biochemical, vasculopathy and neuropathy indicators and the structure of the fecal microbiota during the intervention was analyzed. Result: Glucose metabolism and diabetic complications showed superior remission in Group W with a 0.721 ± 0.742% decline of glycosylated hemoglobin after 4 months. The proportion of patients with diabetic peripheral neuropathy (Toronto Clinical Scoring System, TCSS ≥ 6) was significantly lower in Group W than in Group C. Both the left and right sural sensory nerve conduction velocity (SNCV-left sural and SNCV-right sural) slightly decreased in Group C and slightly increased in Group W. Additionally, the abundances of Bifidobacterium, Faecalibacterium and Anaerostipes were higher in Group W, and the abundances of Weissella, Klebsiella, Cronobacter and Enterobacteriaceae_unclassified were lower than those in Group C at month 2. At the end of month 4, Bifidobacterium remained more abundant in Group W. Conclusion: To our knowledge, this is the first report of improvement to diabetes complications by using a dietary supplement in such a short-term period. The enrichment of SCFA-producing bacteria might be responsible for the attenuation of T2D and its complications. Clinical trial registration number: http://www.chictr.org.cn/edit.aspx?pid=23309&htm=4, identifier ChiCTR-IOR-17013656.

Crosstalk between the gut microbiota and postmenopausal osteoporosis: Mechanisms and applications.

Postmenopausal osteoporosis (PMO) results from a reduction in bone mass and microarchitectural deterioration in bone tissue due to estrogen deficiency, which may increase the incidence of fragility fractures. The number of people suffering from PMO has increased over the years because of the rapidly aging population worldwide. However, several pharmacological agents for the treatment of PMO have many safety risks and impose a heavy financial burden to patients and society. In recent years, the "gut-bone" axis has been proposed as a new approach in the prevention and treatment of PMO. This paper reviews the relationship between the gut microbiota and PMO, which mainly includes the underlying mechanisms between hormones, immunity, nutrient metabolism, metabolites of the gut microbiota and intestinal permeability, and explores the possible role of the gut microbiota in these processes. Finally, we discuss the therapeutic effects of diet, prebiotics, probiotics, and fecal microbiota transplantation on the gut microbiota.

Extension of the Life Span by Acarbose: Is It Mediated by the Gut Microbiota?

Acarbose can extend the life span of mice through a process involving the gut microbiota. Several factors affect the life span, including mitochondrial function, cellular senescence, telomere length, immune function, and expression of longevity-related genes. In this review, the effects of acarbose-regulated gut microbiota on the life span-influencing factors have been discussed. In addition, a novel theoretical basis for improving our understanding of the mechanisms by which acarbose extends the life span of mice has been suggested.

Maximizing the peroxidase-like activity of Pd@PtxRu4-x nanocubes by precisely controlling the shell thickness and their application in colorimetric biosensors.

Although the application of nanoscale artificial enzymes in various industries is an attractive way to circumvent the intrinsic drawbacks of natural enzymes, their catalytic constant (Kcat) as a critical reaction parameter is far from satisfactory. Presented here is the rational design and fabrication of a unique peroxidase mimic catalyst based upon Pd@PtxRu4-x (1 ≤ x ≤ 3) prepared by coating PtRu alloy as conformal, ultrathin shells on Pd nanocrystals. Benefiting from an optimal Pt/Ru ratio and well-defined {100} facets, together with confining the Pt-Ru alloy to a shell of averagely 3.3-atomic-layer thick (i.e. Pd@Pt-Ru3.3L), the nanocrystals exhibit the highest catalytic activity and kinetics (1.2 × 106 s-1), resulting in a significant increase of catalytic activity compared with the classical PtRu nanozyme (3.6 × 103 s-1) and horseradish peroxidase (4.0 × 103 s-1), respectively. The following density functional theory calculations demonstrate that the origin of the superior catalytic performance could be attributed to the modulation of the adsorption behavior of the key reaction intermediates on the surface. As a proof of concept, its peroxidase mimicking ability is adopted for sensing glucose and glutathione molecules in human serum, with a long linear range and high selectivity. This work opens new horizons for the future development of advanced catalysts based upon alloy nanocrystals for various applications.

Roles of the gut microbiota in severe SARS-CoV-2 infection.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread worldwide. The pathophysiological mechanisms linking gut dysbiosis and severe SARS-CoV-2 infection are poorly understood, although gut microbiota disorders are related to severe SARS-CoV-2 infections. The roles of the gut microbiota in severe SARS-CoV-2 infection were compared with those in respiratory viral infection, which is an easily understood and enlightening analogy. Secondary bacterial infections caused by immune disorders and antibiotic abuse can lead to dysregulation of the gut microbiota in patients with respiratory viral infections. The gut microbiota can influence the progression of respiratory viral infections through metabolites and the immune response, which is known as the gut-lung axis. Angiotensin-converting enzyme 2 is expressed in both the lungs and the small intestine, which may be a bridge between the lung and the gut. Similarly, SARS-CoV-2 infection has been shown to disturb the gut microbiota, which may be the cause of cytokine storms. Bacteria in the gut, lung, and other tissues and respiratory viruses can be considered microecosystems and may exert overall effects on the host. By referencing respiratory viral infections, this review focused on the mechanisms involved in the interaction between SARS-CoV-2 infections and the gut microbiota and provides new strategies for the treatment or prevention of severe SARS-CoV-2 infections by improving gut microbial homeostasis.

The application of the lytic domain of endolysin from Staphylococcus aureus bacteriophage in milk.

Staphylococcus aureus is a widespread foodborne pathogen that threatens human health. In particular, multidrug-resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA) are emerging problems in modern health care, food safety, and animal health, which require the development of new antimicrobials to replace overused conventional antibiotics. Dairy products can potentially act as vehicles for the transmission of S. aureus and other antibiotic-resistant strains from the farm into the general human population, and should be controlled during the production and storage process. Recently, bacteriophage endolysins, which degrade the cell wall that is indispensable for bacteria, have been deemed promising antimicrobial agents. In this study, one endolysin, LysGH15, demonstrated prominent antimicrobial efficacy against S. aureus, as did its catalytic domain, cysteine, histidine-dependent amidohydrolase/peptidases (CHAP)LysGH15 alone. The LysGH15 and CHAPLysGH15 exhibited different characteristics in one MRSA strain (MRSA 2701), reaching the highest activity under different conditions (35°C and pH 6.0 for LysGH15, 40°C and pH 9.0 for CHAPLysGH15). A difference in the sensitivity of LysGH15 and CHAPLysGH15 to NaCl concentration was found, where the lytic activity of LysGH15 depends strongly on its binding domain's binding capacity, which is positively correlated with the NaCl concentration, whereas the CHAPLysGH15 activity showed a negative correlation with the NaCl concentration. When the NaCl concentration was 450 mM, the lytic activity of LysGH15 reached its peak, whereas the lytic activity of CHAPLysGH15 was the highest in the absence of NaCl. The difference in NaCl sensitivity between LysGH15 and CHAPLysGH15 may be due to the sensitivity of the SH3b binding protein of LysGH15 to NaCl. The CHAPLysGH15 was tested as a biopreservative in whole and skim milk and exerted effective control against S. aureus (declined by approximately 2.5 log10 cfu/mL when incubated at 4°C for 8 h), which suggests promise for application in dairy products.

Natural edible materials made of protein-functionalized aerogel particles for postprandial hyperglycemia management.

α-Amylase inhibitors (α-AIs) delay digestion of dietary starch by inhibiting α-amylase in the gut, thereby reducing the postprandial glycemia, which is beneficial to the patients with obesity and diabetes. The proteinaceous α-AIs from wheat can effectively control starch digestion and regulate postprandial hyperglycemia. However, their gastric intolerance remains a challenge, which limits its commercial production and industrial application. In this study, sodium alginate/chitosan aerogels loaded with wheat protein α-AIs were prepared and evaluated as potential transportation and protection matrices for important components in food or pharmaceutical applications. Specifically, the biodegradable aerogel cross-linked with sodium alginate-chitosan-calcium chloride, has a large surface area and open porous structure, which can adsorb staple wheat proteins as an integrated edible material to block around 88,660 U/g of α-amylase activity. The aerogel particles were able to protect the activity of wheat α-AIs in the stomach, leading to the slow passage of the wheat α-AIs through the small intestine to inhibit starch digestion more effectively. Animal experiments further showed that the postprandial blood glucose levels in rats were effectively controlled through delayed increase, after administration of wheat protein-functionalized aerogel particles loaded with wheat α-AIs, which are natural biological macromolecules. This is a novel, safe, and economical method for the prevention and pretreatment of diabetes.

Glycyrrhetic Acid 3-O-Mono-ß-d-glucuronide (GAMG): An Innovative High-Potency Sweetener with Improved Biological Activities.

Glycyrrhetic acid 3-O-mono-ß-d-glucuronide (GAMG) is an important derivative of glycyrrhizin (GL) and has attracted considerable attention, especially in the food and pharmaceutical industries, due to its natural high sweetness and strong biological activities. The biotransformation process is becoming an efficient route for GAMG production with the advantages of mild reaction conditions, environmentally friendly process, and high production efficiency. Recent studies showed that several ß-glucuronidases (ß-GUS) are key GAMG-producing enzymes, displaying a high potential to convert GL directly into the more valuable GAMG and providing new insights into the generation of high-value compounds. This review provides details of the structural properties, health benefits, and potential applications of GAMG. The progress in the development of the biotransformation processes and fermentation strategies to improve the yield of GAMG is also discussed. This work further summarizes recent advances in the enzymatic synthesis of GAMG using ß-GUS with emphasis on the physicochemical and biological properties, molecular modifications, and enzymatic strategies to improve ß-GUS biocatalytic efficiencies. This information contributes to a better framework to explore production and application of bioactive GAMG.

[Construction of recombinant plasmids containing threonine operon and their effects on L-threonine accumulation].

OBJECTIVE: We reconstructed two recombinant plasmids and studied their effects on L-threonine accumulation of Escherichia coli W3110. METHODS: We amplified the threonine operon containing ThrLp promoter, lead peptide thrL, thrA, thrB and thrC genes by PCR from E. coli W3110 chromosome and ligated it into the pMD19 T-vector. Site-directed mutation were carried out by gene splicing by overlap extension PCR to release the feedback inhibition of aspartokinase I (thrA). Two recombinant plasmids pWYE112 and pWYE134 were transformed into E. coli W3110 by electroporation. Fed-batch cultures of E. coli W3110 were carried out in 5-Liter fermentors and the L-threonine concentration was measured by HPLC. RESULTS: Fed-batch fermentation results showed that E. coli W3110 could accumulate little L-threonine (0.036 +/- 0.004 g/L) but recombinant E. coli W3110 harboring the plasmid pWYE112 containing a threonine operon exhibited a L-threonine production of 2.590 +/- 0.115 g/L. Furthermore, L-threonine production reached 9.223 +/- 1.279 g/L when the feedback inhibition of thrA was released. CONCLUSION: Overexpression of threonine operon can lead to the accumulation of L-threonine. Further release of feedback inhibition of aspartokinase I can enhance its accumulation.