A novel machine learning model to predict high on-treatment platelet reactivity on clopidogrel in Asian patients after percutaneous coronary intervention

BACKGROUND

Various genetic and nongenetic variables influence the high on-treatment platelet reactivity (HTPR) in patients taking clopidogrel.

AIM

This study aimed to develop a novel machine learning (ML) model to predict HTPR in Chinese patients after percutaneous coronary intervention (PCI).

METHOD

This cohort study collected information on 507 patients taking clopidogrel. Data were randomly divided into a training set (90%) and a testing set (10%). Nine candidate Machine learning (ML) models and multiple logistic regression (LR) analysis were developed on the training set. Their performance was assessed according to the area under the receiver operating characteristic curve, precision, recall, F1 score, and accuracy on the test set. Model interpretations were generated using importance scores by transforming model variables into scaled features and representing in radar plots. Finally, we established a prediction platform for the prediction of HTPR.

RESULTS

A total of 461 patients (HTPR rate: 19.52%) were enrolled in building the prediction model for HTPR. The XGBoost model had an optimized performance, with an AUC of 0.82, a precision of 0.80, a recall of 0.44, an F1 score of 0.57, and an accuracy of 0.87, which was superior to those of LR. Furthermore, the XGBoost method identified 7 main predictive variables. To facilitate the application of the model, we established an XGBoost prediction platform consisting of 7 variables and all variables for the HTPR prediction.

CONCLUSION

A ML-based approach, such as XGBoost, showed optimum performance and might help predict HTPR on clopidogrel after PCI and guide clinical decision-making. Further validated studies will strengthen this finding.

Dual role of Nrf2/HO-1 pathway in Z-ligustilide-induced ferroptosis against AML cells

BACKGROUND

The scarcity of drugs targeting AML cells poses a significant challenge in AML management. Z-Ligustilide (Z-LIG), a phthalide compound, shows promising pharmacological potential as a candidate for AML therapy. However, its precise selective mechanism remains unclear.

PURPOSE

In order to assess the selective inducement effects of Z-LIG on ferroptosis in AML cells and explore the possible involvement of the Nrf2/HO-1 pathway in the regulation of ferroptosis.

METHODS

Through in vitro cell proliferation and in vivo tumor growth tests, the evaluation of Z-LIG's anticancer activity was conducted. Ferroptosis was determined by the measurement of ROS and lipid peroxide levels using flow cytometry, as well as the observation of mitochondrial morphology. To analyze the iron-related factors, western blot analysis was employed. The up-regulation of the Nrf2/HO-1 axis was confirmed through various experimental techniques, including CRISPR/Cas9 gene knockout, fluorescent probe staining, and flow cytometry. The efficacy of Z-LIG in inducing ferroptosis was further validated in a xenograft nude mouse model.

RESULTS

Our study revealed that Z-LIG specifically triggered lipid peroxidation-driven cell death in AML cells. Z-LIG downregulated the total protein and nuclear entrance levels of IRP2, resulting in upregulation of FTH1 and downregulation of TFR1. Z-LIG significantly increased the susceptibility to ferroptosis by upregulating ACSL4 levels and simultaneously suppressing the activity of GPX4. Notably, the Nrf2/HO-1 pathway displayed a twofold impact in the ferroptosis induced by Z-LIG. Mild activation suppressed ferroptosis, while excessive activation promoted it, mainly driven by ROS-induced labile iron pool (LIP) accumulation in AML cells, which was not observed in normal human cells. Additionally, Nrf2 knockout and HO-1 knockdown reversed iron imbalance and mitochondrial damage induced by Z-LIG in HL-60 cells. Z-LIG effectively inhibited the growth of AML xenografts in mice, and Nrf2 knockout partially weakened its antitumor effect by inhibiting ferroptosis.

CONCLUSION

Our study presents biological proof indicating that the selective initiation of ferroptosis in leukemia cells is credited to the excessive activation of the Nrf2/HO-1 pathway triggered by Z-LIG.

IL-7 promotes CD19-directed CAR-T cells proliferation through miRNA-98-5p by targeting CDKN1A

CAR-T targeting CD19 have achieved significant effects in the treatment of B-line leukemia and lymphoma. However, the treated patients frequently relapsed and could not achieve complete remission. Therefore, improving the proliferation and cytotoxicity of CAR-T cells, reducing exhaustion and enhancing infiltration capacity are still issues to be solved. The IL-7 has been shown to enhance the memory characteristics of CAR-T cells, but the specific mechanism has yet to be elaborated. miRNAs play an important role in T cell activity. However, whether miRNA is involved in the activation of CAR-T cells by IL-7 has not yet been reported. Our previous study had established the 3rd generation CAR-T cells. The present study further found that IL-7 significantly increased the proliferation of anti-CD19 CAR-T cells, the ratio of CD4 + CAR + cells and the S phase of cell cycle. In vivo study NAMALWA xenograft model showed that IL-7-stimulated CAR-T cells possessed stronger tumoricidal efficiency. Further we validated that IL-7 induced CAR-T cells had low expression of CDKN1A and high expression of miRNA-98-5p. Additionally, CDKN1A was associated with miRNA-98-5p. Our results, for the first time, suggested IL-7 could conspicuously enhance the proliferation of CAR-T cells through miRNA-98-5p targeting CDKN1A expression, which should be applied to CAR-T production.

Z-ligustilide preferentially caused mitochondrial dysfunction in AML HL-60 cells by activating nuclear receptors NUR77 and NOR1

BACKGROUND

Nuclear receptors NUR77 and NOR1 were identified as critical targets in acute myeloid leukemia (AML) therapy. Previously, we showed that Z-ligustilide (Z-LIG) selectively targeted AML by restoring NUR77 and NOR1. However, its downstream mechanisms are yet to be elucidated.

METHODS

SRB staining assay was used to measure cell viability. Cell apoptosis, mitochondrial membrane potential and mitochondrial reactive oxygen species were analyzed using flow cytometry. The potential targets of Z-LIG in AML HL-60 cells were evaluated by RNA sequencing. Changes in RNA levels were measured using quantitative RT-qPCR and western blot analysis was used to detect the expression of proteins.

RESULTS

Z-LIG preferentially induced mitochondrial dysfunction in HL-60 cells compared with 293T cells. Furthermore, RNA sequencing revealed that mitochondrial transcription and translation might be potential Z-LIG targets inhibiting HL-60 cells. NUR77/NOR1 overexpression significantly reduced the mitochondrial ATP and mitochondrial membrane potential and increased mitochondrial reactive oxygen species in HL-60 cells but not in 293T cells. Moreover, Z-LIG induced mitochondrial dysfunction by restoring NUR77 and NOR1 in HL-60 cells. Compared with HL-60 cells, the apoptosis-inducing activities of NUR77/NOR1 and Z-LIG were significantly reduced in HL-60 ρ0 cells depleted in mitochondrial DNA (mt-DNA). Moreover, NUR77/NOR1 and Z-LIG downregulated mitochondrial transcription and translation related proteins in HL-60 cells. Notably, Z-LIG remarkably reduced mitochondrial ATP in primary AML cells and showed anti-AML activity in mouse models of human AML.

CONCLUSIONS

Collectively, our findings suggested that Z-LIG selectively induces mitochondrial dysfunction in AML HL-60 cells by restoring NUR77 and NOR1, a process associated with interference in mtDNA transcription.

TFP5-Mediated CDK5 Activity Inhibition Improves Diabetic Nephropathy via NGF/Sirt1 Regulating Axis

Diabetic nephropathy (DN) is one of the leading causes of chronic kidney disease (CKD), during which hyperglycemia is composed of the major force for the deterioration to end-stage renal disease (ESRD). However, the underlying mechanism triggering the effect of hyperglycemia on DN is not very clear and the clinically available drug for hyperglycemia-induced DN is in need of urgent development. Here, we found that high glucose (HG) increased the activity of cyclin-dependent kinase 5 (CDK5) dependent on P35/25 and which upregulated the oxidative stress and apoptosis of mouse podocytes (MPC-5). TFP5, a 25-amino acid peptide inhibiting CDK5 activity, decreased the secretion of inflammation cytokines in serum and kidney, and effectively protected the kidney function in db/db mouse from hyperglycemia-induced kidney injuries. In addition, TFP5 treatment decreased HG-induced oxidative stress and cell apoptosis in MPC-5 cells and kidney tissue of db/db mouse. The principal component analysis (PCA) of RNA-seq data showed that MPC-5 cell cultured under HG, was well discriminated from that under low glucose (LG) conditions, indicating the profound influence of HG on the properties of podocytes. Furthermore, we found that HG significantly decreased the level of NGF and Sirt1, both of which correlated with CDK5 activity. Furthermore, knockdown of NGF was correlated with the decreased expression of Sirt1 while NGF overexpression leads to upregulated Sirt1 and decreased oxidative stress and apoptosis in MPC-5 cells, indicating the positive regulation between NGF and Sirt1 in podocytes. Finally, we found that K252a, an inhibitor of NGF treatment could undermine the protective role of TFP5 on hyperglycemia-induced DN in db/db mouse model. In conclusion, the CDK5-NGF/Sirt1 regulating axis may be the novel pathway to prevent DN progression and TFP5 may be a promising compound to improved hyperglycemia induced DN.

[Analysis of clinical effect of blood purification on acute benzene-based thinner poisoning]

Objective: To investigate the clinical significance of blood purification on changes in serum toxicant concentration and prognosis of acute benzene-based thinner poisoning. Methods: A total of 44 patients with acute benzene-based thinner poisoning admitted to the emergency department of Characteristic Medical Center of Armed Police from August 2013 to August 2020 were collected and divided into a blood purification group (24 cases) and a conventional treatment group (20 cases) , the general data, toxicant concentrations and prognosis of the two groups of patients were analyzed, and logistic regression analysis was performed on the influencing factors of the prognosis to explore the clinical effect of blood purification. Results: The concentration of poisons in the blood purification group at 24 hours after treatment was significantly lower than that in the conventional treatment group (t=6.76, P<0.001) , and the reduction in the concentration of poisons was significantly higher than that in the conventional treatment group (t=3.33, P=0.002) . The overall improvement rate in the blood purification group was 91.7% (22/24) , which was higher than that in the conventional treatment group (60.0%, 12/20) . Logisitic regression analysis showed that blood purification treatment method was the main factor affecting the prognosis of patients (OR=7.605×10(-5), 95%CI: 6.604×10(-8)-0.087, P=0.008) , and the toxic dose was a synergistic effect on the prognosis of patients factor (OR=1.038, 95%CI: 1.008-1.068, P=0.011) . Conclusion: Early blood purification treatment in patients with acute benzene-based thinner poisoning can rapidly reduce blood toxin concentration, avoid disease progression, and ultimately improve patient prognosis.

The prognosis biomarkers based on m6A-related lncRNAs for myeloid leukemia patients

Background

Chronic myeloid leukemia (CML) and acute myeloid leukemia (AML) are two common malignant disorders in leukemia. Although potent drugs are emerging, CML and AML may still relapse after the drug treatment is stopped. N6-methyladenosine (m6A) and lncRNAs play certain roles in the occurrence and development of tumors, but m6A-modified LncRNAs in ML remain to be further investigated.

Methods

In this study, we extracted and analyzed the TCGA gene expression profile of 151 ML patients and the clinical data. On this basis, we then evaluated the immune infiltration capacity of ML and LASSO-penalized Cox analysis was applied to construct the prognostic model based on m6A related lncRNAs to verify the prognostic risk in clinical features of ML. Quantitative reverse transcription PCR was used to detect the expression level of LncRNA in in ML cell lines K562, MOLM13 and acute monocytic leukemia cell line THP-1.

Results

We found 70 m6A-related lncRNAs that were related to prognosis, and speculated that the content of stromal cells and immune cells would correlate with the survival of patients with ML. Next, Prognostic risk model of m6A-related lncRNAs was validated to have excellent consistency in clinical features of ML. Finally, we verified the expression levels of CRNDE, CHROMR and NARF-IT1 in ML cell lines K562, MOLM13 and acute monocytic leukemia cell line THP-1, which were significant.

Conclusions

The research provides clues for the prognosis prediction of ML patients by using the m6A-related lncRNAs model we have created, and clarifies the accuracy and authenticity of it.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-02428-3.

Asymmetric electrocarboxylation of 4′-methylacetophenone over PrCoO3 perovskites

Asymmetric electrocarboxylation of aromatic ketones has been achieved over PrCoO3 perovskites with the help of chiral auxiliary t-Bu(R,R)salen(Co[ii]) under CO2 atmosphere.

Enhancing Thermostability of Lipase from Pseudomonas alcaligenes for producing L-menthol by the CREATE Strategy

The Lipase from Pseudomonas alcaligenes (PaL) catalyzes the hydrolysis of racemic menthol propionate to produce L-menthol, one of the most important flavoring agents in food, cosmetics and pharmaceuticals industries. However,...

Substrate access path-guided engineering of L-threonine aldolase for improving diastereoselectivity

The L-threonine aldolase from Leishmania major was engineered to improve diastereoselectivity by a CAST/ISM strategy, providing insights into the relationship between physico -chemical properties of substrate access path and diastereoselectivity....

Electrochemically Promoted Asymmetric Transfer Hydrogenation of 2,2,2-Trifluoroacetophenone

The study reported an electrochemically promoted asymmetric hydrogen transfer reaction of 2,2,2-trifluoroacetophenone with a chiral Ru complex. (R)-α-(Trifluoromethyl) benzyl alcohol with a 96% yield and 94% ee could be obtained with only a 0.5 F mol^-1 charge amount at room temperature and normal pressure.

Combined Biosynthetic Pathway Engineering and Storage Pool Expansion for High-Level Production of Ergosterol in Industrial Saccharomyces cerevisiae

Ergosterol, a terpenoid compound produced by fungi, is an economically important metabolite serving as the direct precursor of steroid drugs. Herein, ergsosterol biosynthetic pathway modification combined with storage capacity enhancement was proposed to synergistically improve the production of ergosterol in Saccharomyces cerevisiae. S. cerevisiae strain S1 accumulated the highest amount of ergosterol [7.8 mg/g dry cell weight (DCW)] among the wild-type yeast strains tested and was first selected as the host for subsequent metabolic engineering studies. Then, the push and pull of ergosterol biosynthesis were engineered to increase the metabolic flux, overexpression of the sterol acyltransferase gene ARE2 increased ergosterol content to 10 mg/g DCW and additional overexpression of a global regulatory factor allele (UPC2-1) increased the ergosterol content to 16.7 mg/g DCW. Furthermore, considering the hydrophobicity sterol esters and accumulation in lipid droplets, the fatty acid biosynthetic pathway was enhanced to expand the storage pool for ergosterol. Overexpression of ACC1 coding for the acetyl-CoA carboxylase increased ergosterol content from 16.7 to 20.7 mg/g DCW. To address growth inhibition resulted from premature accumulation of ergosterol, auto-inducible promoters were employed to dynamically control the expression of ARE2, UPC2-1, and ACC1. Consequently, better cell growth led to an increase of ergosterol content to 40.6 mg/g DCW, which is 4.2-fold higher than that of the starting strain. Finally, a two-stage feeding strategy was employed for high-density cell fermentation, with an ergosterol yield of 2986.7 mg/L and content of 29.5 mg/g DCW. This study provided an effective approach for the production of ergosterol and other related terpenoid molecules.

Umbilical Cord Mesenchymal Stem Cell-Derived Exosomes Ameliorate HaCaT Cell Photo-Aging

Umbilical cord mesenchymal stem cells (UCMSCs) have been identified as a potentially ideal cell type for use in regenerative therapeutic contexts owing to their excellent paracrine secretory abilities and other desirable properties. Previous work has shown that stem cell-derived exosomes can effectively reduce skin aging, but few studies have specifically focused on the role of UCMSC-derived exosomes in this context. In this study, we isolated exosomes derived from UCMSCs grown in a three-dimensional culture system and explored their ability to modulate the photo-aging of HaCaT keratinocytes. Cell viability and proliferation were assessed using CCK8 assay, whereas wound healing and transwell assays were used to assess cell migratory capabilities. UVB irradiation (60 mJ/cm²) was used to induce photo-aging of HaCaT cells. TUNEL and SA-β-Gal staining were used to explore HaCaT cell apoptosis and senescence, respectively, whereas real-time quantitative PCR was used to assess the expression of relevant genes at the mRNA level. We found that UCMSC-derived exosomes were able to enhance normal HaCaT cell proliferation and migration while also inhibiting UVB-induced damage to these cells. These exosomes also reduced HaCaT cell apoptosis and senescence, increasing collagen type I expression and reducing matrix metalloproteinase (MMP1) expression in photo-aged HaCaT cells. Together, these findings indicate that UCMSC-derived exosomes have the potential to be used therapeutically to suppress skin aging.

Evaluation of piggyBac-mediated anti-CD19 CAR-T cells after ex vivo expansion with aAPCs or magnetic beads

Adoptive immunotherapy is a new potential method of tumour therapy, among which anti‐CD19 chimeric antigen receptor T‐cell therapy (CAR‐T cell), is a typical treatment agent for haematological malignancies. Previous clinical trials showed that the quality and phenotype of CAR‐T cells expanded ex vivo would seriously affect the tumour treatment efficacy. Although magnetic beads are currently widely used to expand CAR‐T cells, the optimal expansion steps and methods have not been completely established. In this study, the differences between CAR‐T cells expanded with anti‐CD3/CD28 mAb‐coated beads and those expanded with cell‐based aAPCs expressing CD19/CD64/CD86/CD137L/mIL‐15 counter‐receptors were compared. The results showed that the number of CD19‐specific CAR‐T cells with a 4‐1BB and CD28 co‐stimulatory domain was much greater with stimulation by aAPCs than that with beads. In addition, the expression of memory marker CD45RO was higher, whereas expression of exhausted molecules was lower in CAR‐T cells expanded with aAPCs comparing with the beads. Both CAR‐T cells showed significant targeted tumoricidal effects. The CAR‐T cells stimulated with aAPCs secreted apoptosis‐related cytokines. Moreover, they also possessed marked anti‐tumour effect on NAMALWA xenograft mouse model. The present findings provided evidence on the safety and advantage of two expansion methods for CAR‐T cells genetically modified by piggyBac transposon system.

CRISPR-Assisted Multiplex Base Editing System in Pseudomonas putida KT2440

Pseudomonas putida (P. putida) KT2440 is a paradigmatic environmental-bacterium that possesses significant potential in synthetic biology, metabolic engineering and biodegradation applications. However, most genome editing methods of P. putida KT2440 depend on heterologous repair proteins and the provision of donor DNA templates, which is laborious and inefficient. In this report, an efficient cytosine base editing system was established by using cytidine deaminase (APOBEC1), enhanced specificity Cas9 nickase (eSpCas9pp^D10A) and the uracil DNA glycosylase inhibitor (UGI). This constructed base editor converts C-G into T-A in the absence of DNA strands breaks and donor DNA templates. By introducing a premature stop codon in target spacers, we successfully applied this system for gene inactivation with an efficiency of 25–100% in various Pseudomonas species, including P. putida KT2440, P. aeruginosa PAO1, P. fluorescens Pf-5 and P. entomophila L48. We engineered an eSpCas9pp^D10A-NG variant with a NG protospacer adjacent motif to expand base editing candidate sites. By modifying the APOBEC1 domain, we successfully narrowed the editable window to increase gene inactivation efficiency in cytidine-rich spacers. Additionally, multiplex base editing in double and triple loci was achieved with mutation efficiencies of 90–100% and 25–35%, respectively. Taken together, the establishment of a fast, convenient and universal base editing system will accelerate the pace of future research undertaken with P. putida KT2440 and other Pseudomonas species.

Efficient heterologous expression of nicotinate dehydrogenase in Comamonas testosteroni CNB-2 with transcriptional, folding enhancement strategy

Nicotinate dehydrogenase (NDHase) from Comamonas testosteroni JA1 catalyzes the C6 hydroxylation of 3-cyanopyridine with high regional selectivity, which is a very difficult and complex reaction for chemical synthesis. However, because NDHase is a membrane protein with three subunits (ndhS, ndhL and ndhM), it is difficult to express the enzyme in a functional form using common hosts such as Escherichia coli, Bacilus subtilis or Pichia pastoris. Furthermore, the enzyme requires special electron transfer chains in the membrane system for proper catalytic activity. Thus, we investigated the expression of NDHase in non-model bacterial strains, which are evolutionarily similar to C. testosteroni JA1, using several broad-host plasmids with different copy numbers as expression vectors. We successfully expressed NDHase in soluble from using the pVLT33 vector in C. testosteroni CNB-2, and found the activity of enzyme to be 40.6 U/L. To further improve the expression of NDHase in C. testosteroni CNB-2, we trialed a T7-like MmP1 system, composed of MmP1 RNA polymerase and an MmP1 promoter, which is used for transcriptional control in non-model bacteria. This increased protein expression and enzyme activity doubled to 90.5 U/L. A molecular chaperone was co-expressed using pBBR1 MCS-5 in the same host to improve the efficiency of folding and assembly of multi-subunit structures. The maximum activity was 115 U/L using the molecular chaperone GroES-EL, far surpassing the previously reported level, although expression was almost equivalent. These results indicate that a strategy involving the construction of a T7-like system and co-expression of a molecular chaperone offers an efficient approach for heterologous expression of enzymes that are difficult to express in functional forms using conventional hosts.

Advancement of multi-target drug discoveries and promising applications in the field of Alzheimer's disease

Complex diseases (e.g., Alzheimer's disease) or infectious diseases are usually caused by complicated and varied factors, including environmental and genetic factors. Multi-target (polypharmacology) drugs have been suggested and have emerged as powerful and promising alternative paradigms in modern medicinal chemistry for the development of versatile chemotherapeutic agents to solve these medical challenges. The multifunctional agents capable of modulating multiple biological targets simultaneously display great advantages of higher efficacy, improved safety profile, and simpler administration compared to single-targeted agents. Therefore, multifunctional agents would certainly open novel avenues to rationally design the next generation of more effective but less toxic therapeutic agents. Herein, the authors review the recent progress made in the discovery and design processes of selective multi-targeted agents, especially the successful application of multi-target drugs for the treatment of Alzheimer's disease.

Prognostic Factors and Recurrence Patterns in T4 Gastric Cancer Patients after Curative Resection

Background: To investigate prognostic factors and recurrence patterns in T4 gastric cancer (GC) patients after curative resection.

Methods: Between January 2004 and December 2014, 249 patients with T4 gastric cancer undergoing curative resection were recruited. Patient characteristics, survival, prognostic factors and recurrence patterns were analyzed.

Results: Our results showed that the median survival time (MST) for T4 gastric cancer after curative resection was 55.47 months, with 59.47 months for T4a (tumor perforating serosa) and 25.90 months for T4b (tumor invasion of the adjacent structure). Multivariate analysis indicated that age (hazard ratio [HR], 1.86; P = 0.006), location of tumor (HR, 1.25, 0.90 - 5.64; P < 0.001) and intraoperative blood loss (HR, 1.85; P = 0.010) were independent prognostic factors for overall survival (OS). After a median follow-up of 25.87 months, a total of 109 (43.8%) patients suffered from recurrence, and 90 patients had been observed specific recurrence sites, among which peritoneal metastasis was the most common recurrence pattern, 59.0% for T4a and 88.3% for T4b, respectively.

Conclusions: For T4 gastric cancer patients after curative resection, older age, gastric cancer of the entire stomach and more intraoperative blood loss were associated with poor OS. The recurrence rate after curative resection for T4 was high, and the most common recurrence pattern was peritoneal metastasis.

Enhancing the thermostability of Rhizopus oryzae lipase by combined mutation of hot-spots and engineering a disulfide bond

Rhizopus oryzae lipase (ROL) is important because of its extreme sn-1,3-regioselectivity, but it shows poor thermostability, which severely restricts its application. In this work, the thermostability of ROL was greatly enhanced by rational design. First, several sites that may affect the thermostability of ROL were identified by multiple-sequence alignment. The half-lives of mutants V209L and D262G at 55 °C were about 4.38- and 4.2-times those of the wild-type, respectively. Then, a disulfide bond was introduced between positions 190 and 238 based on the prediction of Disulfide by Design 2, which greatly improved the thermostability of the protein. The activity of variant E190C/E238C retained about 58.2% after incubation at 55 °C for 720 min, whereas the half-life of wild type ROL was only about 11.7 min. On the basis of the results obtained by the two methods, we carried out a combined mutation. Quadruple mutant V209L/D262G/E190C/E238C was constructed and the thermostability was improved even further. The half-lives at 55 °C and 65 °C were 102.5- and 20-times those of the wild-type ROL. This improvement in thermostability will give ROL wider industrial applicability, especially in the preparation of structured lipids.

[Current status of job burnout in in-service sailors from 13 provinces and cities in China]

Objective: To investigate the current status of job burnout in in-service sailors, and to provide a basis for the development of intervention measures for job burnout in sailors. Methods: From September 2015 to May 2016, stratified cluster random sampling was used to select 6 172 in-service sailors from 13 provinces and cities as research subjects. General demographic data including age, education background, and household registration and occupational characteristics such as job position, navigating zone, and nature of employment were collected. The Maslach Burnout Inventory-General Survey (MBI-GS) was used to measure the levels of emotional exhaustion, depersonalization, low occupational efficiency, and job burnout, and the influencing factors for job burnout were also analyzed. Results: Of all 6 172 in-service sailors, 112 (1.8%) had a positive result in emotional exhaustion, 870 (14.1%) had a positive result in depersonalization, and 3 517 (57.0%) had a positive result in low occupational efficiency. Of all sailors, 63.3% had job burnout, among whom 54.1% had mild burnout, 8.7% had moderate burnout, and 0.5% had severe burnout. There was a significant difference in the score of job burnout between the sailors with different ages, education backgrounds, types of household registration, job positions, navigating zones, ornature of employment (P<0.05). Age, education background, household registration, job position, navigating zone, and nature of employment were major influencing factors for job burnout in in-service sailors (P<0.05) , and there was a higher level of job burnout in the sailors with an age of 30-39 years, education background of junior college or above, urban registration, a job position of second mate/third engineer, a navigating zone of coastal lines, orthe nature of employment of freelance sailor. Conclusion: There is a high incidence rate of job burnout among in-service sailors, and the sailors with a young age, urban registration, a navigating zone of coastal lines, or thenature of employment of freelance sailor tend to have low occupational efficiency. Related measures should be adopted for active intervention.

Increased productivity of L-2-aminobutyric acid and total turnover number of NAD+/NADH in a one-pot system through enhanced thermostability of L-threonine deaminase

OBJECTIVE

To strengthen NADH regeneration in the biosynthesis of L-2-aminobutyric acid (L-ABA).

RESULTS

L-Threonine deaminase (L-TD) from Escherichia coli K12 was modified by directed evolution and rational design to improve its endurance to heat treatment. The half-life of mutant G323D/F510L/T344A at 42 °C increased from 10 to 210 min, a 20-fold increase compared to the wild-type L-TD, and the temperature at which the activity of the enzyme decreased by 50% in 15 min increased from 39 to 53 °C. The mutant together with thermostable L-leucine dehydrogenase from Bacillus sphaericus DSM730 and formate dehydrogenase from Candida boidinii constituted a one-pot system for L-ABA biosynthesis. Employing preheat treatment in the one-pot system, the biosynthesis of L-ABA and total turnover number of NAD⁺/NADH were 0.993 M and 16,469, in contrast to 0.635 M and 10,531 with wild-type L-TD, respectively.

CONCLUSIONS

By using the engineered L-TD during endured preheat treatment, the one-pot system has achieved a higher productivity of L-ABA and total turnover number of coenzyme.

The advancement of multidimensional QSAR for novel drug discovery - where are we headed?

INTRODUCTION

The Multidimensional quantitative structure-activity relationship (multidimensional-QSAR) method is one of the most popular computational methods employed to predict interesting biochemical properties of existing or hypothetical molecules. With continuous progress, the QSAR method has made remarkable success in various fields, such as medicinal chemistry, material science and predictive toxicology. Areas covered: In this review, the authors cover the basic elements of multidimensional -QSAR including model construction, validation and application. It includes and emphasizes the very recent developments of multidimensional -QSAR such as: HQSAR, G-QSAR, MIA-QSAR, multi-target QSAR. The advantages and disadvantages of each method are also discussed and typical examples of their application are detailed. Expert opinion: Although there are defects in multidimensional-QSAR modeling, it is still of enormous help to chemists, biologists and other researchers in various fields. In the authors' opinion, the latest more precise and feasible QSAR models should be further developed by integrating new descriptors, algorithms and other relevant computational techniques. Apart from being applied in traditional fields (e.g. lead optimization and predictive risk assessment), QSAR should be used more widely as a routine method in other emerging research fields including the modeling of nanoparticles(NPs), mixture toxicity and peptides.

Study of recombinant human interleukin-12 for treatment of complications after radiotherapy for tumor patients

AIM

To evaluate the treatment effects of recombinant human interleukin-12 (rhIL-12) on radiotherapy complications, such as severe myelosuppression or pancytopenia, the decline or imbalance of immune function, etc.

METHODS

The patients received high-dose and short-course precise radiotherapy, such as Cyber knife and image-guided radiotherapy (IGRT), which can cause myelosuppression or pancytopenia and immune function decline within a short time. One-hundred subjects were enrolled in the study, and 50 were randomized to a treatment group which used rhIL-12 and 50 were randomized to a control group which used symptomatic and supportive therapy after radiotherapy. The 50 subjects in the treatment group were further divided into five subgroups and intervened with rhIL-12 at a dose of 50, 100, 150, 200 or 250 ng/kg respectively. The dose-effect relationship was observed.

RESULTS

RhIL-12 significantly attenuated the decrease of peripheral blood cells in the treatment group, and immune function was improved after treatment. Due to the different radiation doses, there was a fluctuation within 12 h after treatment but mostly showing an increasing trend. As to the clinical manifestations, 2 patients in the 250 ng/kg subgroup showed low fever after administration, 1 patient in the 200 ng/kg subgroup and 2 patients in the 250 ng/kg subgroup showed mild impairment of liver function during the observation period.

CONCLUSION

RhIL-12 has effective therapeutic and protective effects on complications following radiotherapy, such as the decline of blood cells, myelosuppression and the decline or imbalance of immune function, which indicated good prospects for development and application.

Advances in Computational Structure-Based Drug Design and Application in Drug Discovery

Compared with the increasing and widespread bacterial resistance to clinical medicines and the urgent need for cures of intractable diseases, there is a dramatic decline in the numbers of drugs reaching the market or clinical trials. Accordingly, it has become imperative to discover more rational and efficient strategies to design and develop novel drugs. Structure-based drug design/discovery (SBDD) is one of the computer-aided methods, by which novel drugs are designed or discovered based on the knowledge of 3D structures of the relevant specific targets. During the past few decades, the great potentials and success of SBDD have been seen in the field of drug discovery. In this review, we present an overview of the key mechanisms of SBDD, the frequently used computer programs in SBDD and the reported successful cases. Finally, several typical design processes of lead components from SBDD are also highlighted in detail, such as the discovery of inhibitors of G protein-coupled receptors (GPCRs), antibacterial drugs, and anti-cancer drugs.

Cloning and characterization of a novel lipase from Stenotrophomonas maltophilia GS11: The first member of a new bacterial lipase family XVI

Bacterial lipases are an important group of enzymes that offer enormous potential in organic synthesis, and there is considerable interest in identifying and developing novel bacterial lipases. In previous studies, strains of the genus Stenotrophomonas were proved to be potential source of lipases, but there is little genetic information describing lipase from the genus Stenotrophomonas. We have cloned and characterized a novel lipase (LipSM54), the first lipase described from the genus Stenotrophomonas. Enzymatic study showed that LipSM54 was a cold-active, solvent-tolerant and alkaline lipase. Using bioinformatics tools, LipSM54 was found to be related only to several putative lipases from different bacterial origins, none of which could be assigned to any previously described bacterial lipase family. LipSM54 and these related putative lipases share four conserved motifs around the catalytic residues. These motifs clearly distinguish them from the known bacterial lipase families. Consequently, LipSM54 is the first characterized member of the novel bacterial lipase family.

[Impact of long-term continuous positive airway pressure treatment for patients with obstructive sleep apnea syndrome]

OBJECTIVE

To investigate the long-term efficacy of continuous positive airway pressure (CPAP) treatment for patients with obstructive sleep apnea syndrome (OSAS).

METHODS

This case control study was performed among 154 patients with moderate or severe OSAS between September 2009 and September 2014. Patients were divided into treatment group (n=66, 53 patients with hypertension) and control group (n=88, 67 patients with hypertension). The long-term efficacy of CPAP treatment on clinical events and blood pressure was evaluated.

RESULTS

The combined incidence of death, myocardial infarction, coronary revascularization and stroke events was 1.5% (1/66) in treatment group and 11.4% (10/88) in control group (P<0.05). CPAP treatment also led to more significant reduction in systolic blood pressure ((12.24±18.06) mmHg(1 mmHg=0.133 kPa) to (4.24±16.63) mmHg, P<0.05) in the patients with hypertension in these two groups.

CONCLUSIONS

CPAP treatment could reduce the risk of cardiovascular and neurovascular events for patients with moderate or severe OSAS.

Fragment-based drug discovery and molecular docking in drug design

Fragment-based drug discovery (FBDD) has caused a revolution in the process of drug discovery and design, with many FBDD leads being developed into clinical trials or approved in the past few years. Compared with traditional high-throughput screening, it displays obvious advantages such as efficiently covering chemical space, achieving higher hit rates, and so forth. In this review, we focus on the most recent developments of FBDD for improving drug discovery, illustrating the process and the importance of FBDD. In particular, the computational strategies applied in the process of FBDD and molecular-docking programs are highlighted elaborately. In most cases, docking is used for predicting the ligand-receptor interaction modes and hit identification by structurebased virtual screening. The successful cases of typical significance and the hits identified most recently are discussed.

An improved flurogenic probe for high-throughput screening of 2-deoxyribose aldolases

2-Deoxyribose aldolase-catalyzed C-C bond-forming reactions have become 1 more and more important in synthesis of statins and other drug intermediates. Many methods have focused on improving the aldolase properties and harvesting new aldolases, but a good outcome depends on the efficiency of the high-throughput screening system. We have developed a visible green fluorescence probe based on a coumarin derivative, which can be reversibly modulated by a retro-aldol reaction catalyzed by 2-deoxyribose aldolase for selecting aldolase mutants with high activity. This assay system provides a convenient and effective way for high-throughput screening aldolases as the green fluorescence is sensitively detected and daylight-viewable without the need for specialist equipment. We used our probe to successfully harvest aldolase mutants with higher activities than the parent from a random mutagenesis library.

Introducing a salt bridge into the lipase of Stenotrophomonas maltophilia results in a very large increase in thermal stability

High thermostability of enzymes is a prerequisite for their biotechnological applications. An organic solvent-tolerant and cold-active lipase, from the Stenotrophomonas maltophilia, was unstable above 40 °C in previous studies. To increase the enzyme stability, possible hydrogen-bond networks were simulated by the introduction of a salt bridge in a highly flexible region of the protein. Compared with the wild-type lipase, a mutant lipase (G165D and F73R) showed a >900-fold improvement in half-life at 50 °C, with the optimal activity-temperature increasing from 35 to 90 °C. Therefore, the hydrogen-bond strategy is a powerful approach for improving enzyme stability through the introduction of a salt bridge.