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Given the nonlinear and complex industrial fermentation system, the process analytical technology offers significant advantages for direct and real-time monitoring, control and evaluation of synthetic processes. Here, we introduced a Raman spectroscopy in-line monitoring method for ethanol production by Saccharomyces cerevisiae. First, the feature selection methods in machine learning were used to reduce the dimension of Raman spectral data. The results showed that the model training time is reduced by more than 90% after feature selection, while the prediction performance of glycerol and cell concentration is improved by 14.20% and 17.10% at the RMSE level. Then, 15 machine learning algorithms were called to retrain the model, and hyperparameters were adjusted by grid search. The results demonstrated that the model after adjusting the hyperparameters improved the RMSE of ethanol, glycerol, glucose, and biomass by 9.73%, 4.33%, 22.22%, and 13.79%, respectively. Finally, BaggingRegressor, Support vector regression, BayesianRidge, and VotingRegressor are suitable machine learning algorithms corresponding to the models for predicting glucose, ethanol, glycerol, and cell concentrations, respectively. In addition, the R-squared values were 0.89–0.97, and the RMSE values were 0.06–2.59 g/L on the testing datasets, respectively. The results suggested that machine learning methods can be effectively applied in the modeling and analysis of Raman spectroscopy. Moreover, it is conducive to promoting the optimization of Raman spectroscopy in biological process monitoring, thereby improving industrial production efficiency, and providing novel modeling ideas.

Background: Exosome (Exo) secretion by hypoxic pretreatment adipose-derived mesenchymal stem cells (ADSCs) promotes spinal cord repair after spinal cord injury (SCI). But the mechanism remains unclear. Methods: High-throughput sequencing was used to investigate abnormal expression of circRNA in hypoxic pretreatment ADSCs exosome (HExo) and ADSCs exosome (Exo). The abnormal expression of mRNA in spinal cord tissues after Exo or HExo treatment were also analysis using high-throughput sequencing. Bioinformatics analysis and luciferase reporting analysis were used to clarify the interacted relationship among circRNA, miRNA and mRNA. BV2 cells were employ to analysis the apoptosis, inflammatory cytokines expression under OGD condition by using immunofluorescence, ELISA detection. SCI mice model were constructed and the therapeutic effect of Exo were detected using immunohistochemistry, immunofluorescence. Results: The result show that HExo have more therapeutic effect on spinal cord repair after SCI by activation of autophagy. High-throughput sequencing detection show that circ-Astn1 play a role in HExo mediated spinal cord repair after SCI. Downregulation circ-Astn1 decreased the therapeutic effect of HExo to spinal cord repair after SCI. The study also found that Atg7 play a role in HExo mediated spinal cord repair after SCI. Luciferase reporting analysis confirmed that both miR-138-5p and Atg7 were downstream targets of circ-Astn1. Downregulation of Atg7 or overexpression of miR-138-5p reversed the protective effect of circ-Astn1 to BV2 after exposure to OGD condition. Upregulation circ-Astn1 increased the therapeutic effect of Exo to spinal cord repair after SCI by activation autophagy. Conclusions: In conclusion, ADSC-Exos containing circ-Astn1 promotes spinal cord repair after SCI by targeting miR-138-5p/Atg7 pathway mediated autophagy.

BackgroundMicroglia pyroptosis-induced neuroinflammation has been one of the potential treatment targets for spinal cord injury (SCI). And melatonin is reported to have anti-neuroinflammation effect on SCI, but the underlying mechanism is largely unexplored. In addition, the potential regulatory role of stimulator of interferon genes (STING) mediated innate immune response in the SCI-induced neuroinflammation also remains unknown. The aim of this study is to identify the potential molecular mechanism of the anti-neuroinflammation effect of melatonin in SCI mice and to explore whether STING-mediated signal pathway is involved in this pharmacological process. MethodsIn vivo, the C57BL/6 female mice underwent SCI injury or Sham surgery (laminectomy alone). Melatonin and selective STING antagonist C-176 were administered intraperitoneally after injury in the SCI group once a day for 3 or 28 consecutive days for different experiments. The BMS score system was adopted to assess the motor function of mice. In vitro, the Lipopolysaccharide (LPS)/ATP was combinedly used to induce cell pyroptosis in BV2 microglia and the adenovirus was used to overexpress STING. A series of molecular experiments including Western blot (WB), quantitative real-time polymerase chain reaction (RT-qPCR), enzyme linked immunosorbent assay (ELISA) and immunofluorescence (IF) were performed in vivo and in vitro. ResultsOur results showed that melatonin effectively suppressed NLRP3 inflammasome-induced pyroptosis and STING-mediated pathway after SCI. In addition, C-176 also alleviated the NLRP3 inflammasome-mediated pyroptosis and promoted functional recovery in vivo. In vitro, we also found that melatonin abrogated NLRP3 inflammasome activation in LPS/ATP-induced BV2 cells, while overexpression of STING reversed the anti-pyroptotic role of melatonin. Subsequent results together indicated that the role of melatonin on STING-dependent NLRP3 inflammasome activation may be mediated by decreasing ROS production and cytosolic mtDNA release. ConclusionThis study preliminarily demonstrated that melatonin exerts its anti-neuroinflammation role on SCI by alleviating the NLRP3 inflammasome-mediated pyroptosis, which was mediated by blocking the ROS/mtDNA/STING pathway. It provides us a better understanding of the pathological mechanism after SCI and offer experiment evidence to promote the use of melatonin for SCI.

Background: The aim of this study was to evaluate the biomechanical stability of a lumbar internal fixation system with 3 different fixation techniques by the establishment of a three-dimensional finite element (FE) model of lumbar single level fixation.Methods: A three-dimensional osseoligamentous nonlinear FE model of osteoporosis lumbar 4-5 (male, aged 57 years, height 170 cm, weight 70 kg, bone mineral density T value -2.8SD) was built to detect the biomechanical stability of an internal fixation system with the following 3 screw trajectories: traditional pedicle screw trajectory fixation (TT), cortical bone trajectory (CBT) screw and hybrid pedicle screw fixation (CBT + TT). The location and area of maximal equivalent stress and the angular displacement of this lumbar model with different screw trajectories were measured in anterior bending, posterior extension, lateral bending and during rotation.Results: The angular displacement of this lumbar model with the 3 different screw trajectories was similar, all of which could restrict the angular displacement of lumbar vertebrae. The maximal equivalent stress was located at the border of the CBT screw and rod, with the hybrid screw fixation technique in axial rotation. Conclusion: The use of CBT and TT screws in lumbar internal fixation had similar stability. The CBT screw could be an alternative solution to lumbar short-segmented fixation, but temporary immobilization would be required to avoid the failure of CBT screw fixation due to the increasing stress in position of extensive lateral bending and rotation.

Neuroinflammation-induced secondary injury is an important cause of sustained progression of spinal cord injury. Inflammatory programmed cell death pyroptosis executed by the pore-forming protein gasdermin D (GSDMD) is recently regarded as an essential step of neuroinflammation. However, it is unclear whether CD73, a widely accepted immunosuppressive molecule, can inhibit pyroptosis via mediating GSDMD. Here, we reported molecular evidence for CD73 suppresses the activation of NLRP3 inflammasome complexes to reduce the maturation of GSDMD, leading to decreased pyroptosis in macrophages/microglia. Further analysis revealed that adenosine-A2B adenosine receptor-NF-κB cascade is a possible mechanism of CD73 regulation. Importantly, we determined that CD73 inhibited the expression of GSDMD at the transcriptional level through NF-κB, thereby alleviating macrophages/microglia pyroptosis. What’s more, we confirmed the accumulation of HIF-1α promotes the overexpression of CD73 after SCI, and the increased CD73 in turn upregulates the expression of HIF-1α, eventually forming a positive feedback regulatory loop. In summary, our results demonstrate that CD73 alleviates GSDMD-mediated pyroptosis of macrophages/microglia in spinal cord injury by blocking NF-κB signal. Our data reveal a novel function of CD73 on microphages/microglia pyroptosis, suggesting a unique therapeutic opportunity for mitigating the disease process in SCI. Funding Statement: This work was supported by the National Natural Science Foundation of China [grant number 81772385, 81871522]. Declaration of Interests: The authors declare that they do not have any commercial or associative interest that represents a conflict of interest in connection with the work submitted. Ethics Approval Statement: All study surgical procedures and experiment protocols were performed in accordance with standard guidelines approved by the Ethics Committee of Experimental Research, Shanghai Medical College, Fudan University (Shanghai, China). The animal experiments were approved by the Institutional Animal Care and Use Committee of Fudan University.