Publications by authors named "Maokun Li"

12 Publications

  • Page 1 of 1

Risk factors for the critical illness in SARS-CoV-2 infection: a multicenter retrospective cohort study.

Respir Res 2020 Oct 21;21(1):277. Epub 2020 Oct 21.

Putuo People's Hospital, Department of Bioinformatics, Tongji University, Shanghai, 200092, China.

Background: Prior studies reported that 5 ~ 32% COVID-19 patients were critically ill, a situation that poses great challenge for the management of the patients and ICU resources. We aim to identify independent risk factors to serve as prediction markers for critical illness of SARS-CoV-2 infection.

Methods: Fifty-two critical and 200 non-critical SARS-CoV-2 nucleic acid positive patients hospitalized in 15 hospitals outside Wuhan from January 19 to March 6, 2020 were enrolled in this study. Multivariable logistic regression and LASSO logistic regression were performed to identify independent risk factors for critical illness.

Results: Age older than 60 years, dyspnea, respiratory rate > 24 breaths per min, leukocytosis > 9.5 × 10/L, neutrophilia > 6.3 × 10/L, lymphopenia < 1.1 × 10/L, neutrophil-to-lymphocyte ratio > 3.53, fibrinogen > 4 g/L, d-dimer > 0.55 μg/mL, blood urea nitrogen > 7.1 mM, elevated aspartate transaminase, elevated alanine aminotransferase, total bilirubin > 21 μM, and Sequential Organ Failure Assessment (SOFA) score ≥ 2 were identified as risk factors for critical illness. LASSO logistic regression identified the best combination of risk factors as SOFA score, age, dyspnea, and leukocytosis. The Area Under the Receiver-Operator Curve values for the risk factors in predicting critical illness were 0.921 for SOFA score, 0.776 for age, 0.764 for dyspnea, 0.658 for leukocytosis, and 0.960 for the combination of the four risk factors.

Conclusions: Our findings advocate the use of risk factors SOFA score ≥ 2, age > 60, dyspnea and leukocytosis > 9.5 × 10/L on admission, alone or in combination, to determine the optimal management of the patients and health care resources.
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http://dx.doi.org/10.1186/s12931-020-01492-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7576549PMC
October 2020

Supervised Descent Learning for Thoracic Electrical Impedance Tomography.

IEEE Trans Biomed Eng 2021 Apr 18;68(4):1360-1369. Epub 2021 Mar 18.

Objective: The absolute image reconstruction problem of electrical impedance tomography (EIT) is ill-posed. Traditional methods usually solve a nonlinear least squares problem with some kind of regularization. These methods suffer from low accuracy, poor anti-noise performance, and long computation time. Besides, the integration of a priori information is not very flexible. This work tries to solve EIT inverse problem using a machine learning algorithm for the application of thorax imaging.

Methods: We developed the supervised descent learning EIT (SDL-EIT) inversion algorithm based on the idea of supervised descent method (SDM). The algorithm approximates the mapping from measured data to the conductivity image by a series of descent directions learned from training samples. We designed a training data set in which the thorax contour, and some general structure of lungs, and heart are embedded. The algorithm is implemented in both two-, and three-dimensional cases, and is evaluated using synthetic, and measured thoracic data. Results, and conclusion: For synthetic data, SDL-EIT shows better accuracy, and anti-noise performance compared with traditional Gauss-Newton inversion (GNI) method. For measured data, the result of SDL-EIT is reasonable compared with computed tomography (CT) scan image.

Significance: Using SDL-EIT, prior information can be easily integrated through the specifically designed training data set, and the image reconstruction process can be accelerated. The algorithm is effective in inverting measured thoracic data. It is a potential algorithm for human thorax imaging.
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http://dx.doi.org/10.1109/TBME.2020.3027827DOI Listing
April 2021

Long non‑coding RNA NEAT1 modifies cell proliferation, colony formation, apoptosis, migration and invasion via the miR‑4500/BZW1 axis in ovarian cancer.

Mol Med Rep 2020 Oct 4;22(4):3347-3357. Epub 2020 Aug 4.

Department of Surgery, Jingzhou Hospital of Traditional Chinese Medicine, The Third Clinical Medical College of Yangtze University, Jingzhou, Hubei 434000, P.R. China.

Ovarian cancer (OC) is a frequently occurring malignant tumor in women. Increasing evidence has indicated that long non‑coding RNA (lncRNA) nuclear paraspeckle assembly transcript 1 (NEAT1) participates in OC pathogenesis. Thus, the aim of the present study was to explore the function of NEAT1 during OC progression. The expression levels of NEAT1, microRNA (miR)‑4500 and basic leucine zipper and W2 domain‑containing protein 1 (BZW1) were assessed via reverse transcription‑quantitative PCR and western blotting. Furthermore, cell proliferation, colony formation, apoptosis, migration and invasion were assessed using Cell‑Counting Kit 8, colony formation, flow cytometry and Transwell assays, respectively. Cell glycolysis was analyzed using an XF96 metabolic flux analyzer, and the relationship between miR‑4500 and NEAT1 or BZW1 was verified via dual‑luciferase reporter and RNA binding protein immunoprecipitation assays. miR‑4500 expression levels were low, whereas NEAT1 expression levels were high in OC tissues and cell lines compared with control tissues and cell lines. Moreover, the results indicated that NEAT1 was a sponge of miR‑4500, which directly targeted BZW1. NEAT1 knockdown induced OC cell apoptosis, and inhibited OC cell proliferation, colony formation, migration, invasion and glycolysis. miR‑4500 inhibitor reversed NEAT1 knockdown‑mediated effects. Similarly, miR‑4500 mimic‑mediated effects on cell functions were reversed by BZW1 overexpression. In addition, the results indicated that BZW1 expression was regulated by NEAT1 and miR‑4500. Collectively, the present study suggested that NEAT1 modulated cell proliferation, colony formation, apoptosis, migration, invasion and glycolysis via the miR‑4500/BZW1 axis in OC; therefore, NEAT1 may serve as a therapeutic target for OC.
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http://dx.doi.org/10.3892/mmr.2020.11408DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7453653PMC
October 2020

Ag-Modified g-CN Prepared by a One-Step Calcination Method for Enhanced Catalytic Efficiency and Stability.

ACS Omega 2020 Aug 27;5(31):19615-19624. Epub 2020 Jul 27.

College of Chemistry and Chemical Engineering, Guizhou University, Guizhou 550025, China.

Ag-decorated g-CN (denoted as Ag/CN-) was prepared by a one-step calcination method, and the influences of calcination time on structure, morphology, surface composition, photocatalytic performance, and catalytic reduction activity of the prepared Ag/CN- samples were investigated. The tests showed that the Ag/CN-8 prepared through by calcination for 8 h exhibited the best photocatalytic degradation efficiency of methyl orange (98.7% within 2 h) and the best catalytic reduction property of 4-nitrophenol (100% within 70 s). Meanwhile, these Ag/CN- samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectra (DRS), photoluminescence (PL), photocurrent response, and electrochemical impedance spectroscopy (EIS) Nyquist plots. It was found that the Ag/CN-8 prepared through calcination for 8 h had a higher specific surface area, higher dispersibility of silver nanoparticles (Ag NPs), the widest range of visible light response, and the lowest photogenerated electron-hole recombination rate. The results of the trapping experiments indicated that a superoxide radical plays a major role. Moreover, a possible mechanism of photocatalytic degradation in methyl orange and catalytic reduction 4-nitrophenol was proposed.
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http://dx.doi.org/10.1021/acsomega.0c02161DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7424718PMC
August 2020

Neural network-based supervised descent method for 2D electrical impedance tomography.

Physiol Meas 2020 08 11;41(7):074003. Epub 2020 Aug 11.

State Key Laboratory on Microwave and Digital Communications, Beijing National Research Center for Information Science and Technology (BNRist), Department of Electronic Engineering, Tsinghua University, Beijing 100084, People's Republic of China.

Objective: In this work, we study the application of the neural network-based supervised descent method (NN-SDM) for 2D electrical impedance tomography.

Approach: The NN-SDM contains two stages: offline training and online prediction. In the offline stage, neural networks are iteratively applied to learn a sequence of descent directions for minimizing the objective function, where the training data set is generated in advance according to prior information or historical data. In the online stage, the trained neural networks are directly used to predict the descent directions.

Main Results: Numerical and experimental results are reported to assess the efficiency and accuracy of the NN-SDM for both model-based and pixel-based inversions. In addition, the performance of the NN-SDM is compared with the linear SDM (LSDM), an end-to-end neural network (E2E-NN) and the Gauss-Newton (GN) method. The results demonstrate that the NN-SDM achieves faster convergence than the LSDM and GN method, and achieves a stronger generalization ability than the E2E-NN.

Significance: The NN-SDM combines the strong non-linear fitting ability of the neural network and good generalization capability of the supervised descent method (SDM), which also provides good flexibility to incorporate prior information and accelerates the convergence of iteration.
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http://dx.doi.org/10.1088/1361-6579/ab9871DOI Listing
August 2020

Study on 3-D Acoustic Imaging for Human Thorax Based on Contrast Source Inversion.

IEEE Trans Ultrason Ferroelectr Freq Control 2020 08 28;67(8):1533-1543. Epub 2020 Feb 28.

In this article, we study a 3-D acoustic imaging algorithm that can reconstruct compressibility, attenuation, and density simultaneously based on the contrast source inversion (CSI) method. This is a nonlinear and ill-posed inverse problem. To deal with the nonlinearity, we introduce two asymmetrical contrast sources that are functions of the contrasts and the total field. In this case, the scattered field and the total field are linear with the two contrast sources, and the two contrast sources are also linear with the two contrasts; thus, the nonlinearity is partially alleviated. To mitigate the ill-posedness of this inverse problem, we apply a multifrequency, multitransmitter, and multireceiver setting. Besides, to ensure the robustness of the algorithm, two multiplicative regularization terms are introduced as additional constraints. The reconstruction of those acoustic parameters can be achieved by alternately updating the contrast sources and the contrasts from the knowledge of the pressure field. Numerical studies show good reconstruction of compressibility, attenuation, and density of the synthetic thorax model, which validates the feasibility of imaging human thorax using low-frequency ultrasound.
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http://dx.doi.org/10.1109/TUFFC.2020.2977094DOI Listing
August 2020

Three-Dimensional Electrical Impedance Tomography With Multiplicative Regularization.

IEEE Trans Biomed Eng 2019 09 1;66(9):2470-2480. Epub 2019 Jan 1.

Objective: The multiplicative regularization scheme is applied to three-dimensional electrical impedance tomography (EIT) image reconstruction problem to alleviate its ill-posedness.

Methods: A cost functional is constructed by multiplying the data misfit functional with the regularization functional. The regularization functional is based on a weighted L-norm with the edge-preserving characteristic. Gauss-Newton method is used to minimize the cost functional. A method based on the discrete exterior calculus (DEC) theory is introduced to formulate the discrete gradient and divergence operators related to the regularization on unstructured meshes.

Results: Both numerical and experimental results show good reconstruction accuracy and anti-noise performance of the algorithm. The reconstruction results using human thoracic data show promising applications in thorax imaging.

Conclusion: The multiplicative regularization can be applied to EIT image reconstruction with promising applications in thorax imaging.

Significance: In the multiplicative regularization scheme, there is no need to set an artificial regularization parameter in the cost functional. This helps to reduce the workload related to choosing a regularization parameter which may require expertise and many numerical experiments. The DEC-based method provides a systematic and rigorous way to formulate operators on unstructured meshes. This may help EIT image reconstructions using regularizations imposing structural or spatial constraints.
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http://dx.doi.org/10.1109/TBME.2018.2890410DOI Listing
September 2019

Feasibility study of acoustic imaging for human thorax using an acoustic contrast source inversion algorithm.

J Acoust Soc Am 2018 11;144(5):2782

Schlumberger, Houston, Texas, USA.

In this work, an acoustic imaging method based on contrast source inversion and its feasibility in quantitatively reconstructing compressibility, attenuation, and density of human thorax is studied. In the acoustic wave equation, the inhomogeneity in density makes the relationship between the contrasts and the total pressure highly nonlinear. To reduce this nonlinearity, two contrast sources are introduced to ensure symmetry in the equation, such that the inverse problem can be solved efficiently by alternately updating two contrast sources and two contrasts. Moreover, to improve the stability of the algorithm, the multiplicative regularization scheme with two additive regularization factors is applied. Using this algorithm, acoustic parameters of human thorax from low frequency ultrasound measurement are reconstructed. Numerical results show that the acoustic parameters of human thorax can be properly reconstructed at frequency of tens of kHz using this algorithm.
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http://dx.doi.org/10.1121/1.5078590DOI Listing
November 2018

A Passive Temperature-Sensing Antenna Based on a Bimetal Strip Coil.

Sensors (Basel) 2017 Mar 23;17(4). Epub 2017 Mar 23.

State Key Laboratory on Microwave and Digital Communications, Tsinghua National Laboratory for Information Science and Technology, Department of Electronic Engineering, Tsinghua University, Beijing 100084, China.

A passive temperature-sensing antenna is presented in this paper, which consists of a meandering dipole, a bimetal strip and a back cavity. The meandering dipole is divided into two parts: the lower feeding part and the upper radiating part, which maintain electric contact during operation. As a sensing component, a bimetal strip coil offers a twisting force to rotate the lower feeding part of the antenna when the temperature varies. As a result, the effective length of the dipole antenna changes, leading to a shift of the resonant frequency. Furthermore, a metal back cavity is added to increase the antenna's quality factor Q, which results in a high-sensitivity design. An antenna prototype is designed, fabricated, and measured, which achieves a sensitivity larger than 4.00 MHz/°C in a temperature range from 30 °C to 50 °C and a read range longer than 4 m. Good agreement between the simulation and measurement results is obtained.
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http://dx.doi.org/10.3390/s17040665DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5419778PMC
March 2017

A programmable metasurface with dynamic polarization, scattering and focusing control.

Sci Rep 2016 10 24;6:35692. Epub 2016 Oct 24.

Information and Navigation Institute, Air Force Engineering University, Xi'an, 710077, China.

Diverse electromagnetic (EM) responses of a programmable metasurface with a relatively large scale have been investigated, where multiple functionalities are obtained on the same surface. The unit cell in the metasurface is integrated with one PIN diode, and thus a binary coded phase is realized for a single polarization. Exploiting this anisotropic characteristic, reconfigurable polarization conversion is presented first. Then the dynamic scattering performance for two kinds of sources, i.e. a plane wave and a point source, is carefully elaborated. To tailor the scattering properties, genetic algorithm, normally based on binary coding, is coupled with the scattering pattern analysis to optimize the coding matrix. Besides, inverse fast Fourier transform (IFFT) technique is also introduced to expedite the optimization process of a large metasurface. Since the coding control of each unit cell allows a local and direct modulation of EM wave, various EM phenomena including anomalous reflection, diffusion, beam steering and beam forming are successfully demonstrated by both simulations and experiments. It is worthwhile to point out that a real-time switch among these functionalities is also achieved by using a field-programmable gate array (FPGA). All the results suggest that the proposed programmable metasurface has great potentials for future applications.
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http://dx.doi.org/10.1038/srep35692DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5075904PMC
October 2016

Genetic ablation of Smoothened in pancreatic fibroblasts increases acinar-ductal metaplasia.

Genes Dev 2016 09 15;30(17):1943-55. Epub 2016 Sep 15.

Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio 43210, USA; Cancer Biology and Genetics Department, The Ohio State University, Columbus, Ohio 43210, USA;

The contribution of the microenvironment to pancreatic acinar-to-ductal metaplasia (ADM), a preneoplastic transition in oncogenic Kras-driven pancreatic cancer progression, is currently unclear. Here we show that disruption of paracrine Hedgehog signaling via genetic ablation of Smoothened (Smo) in stromal fibroblasts in a Kras(G12D) mouse model increased ADM. Smo-deleted fibroblasts had higher expression of transforming growth factor-α (Tgfa) mRNA and secreted higher levels of TGFα, leading to activation of EGFR signaling in acinar cells and increased ADM. The mechanism involved activation of AKT and noncanonical activation of the GLI family transcription factor GLI2. GLI2 was phosphorylated at Ser230 in an AKT-dependent fashion and directly regulated Tgfa expression in fibroblasts lacking Smo Additionally, Smo-deleted fibroblasts stimulated the growth of Kras(G12D)/Tp53(R172H) pancreatic tumor cells in vivo and in vitro. These results define a non-cell-autonomous mechanism modulating Kras(G12D)-driven ADM that is balanced by cross-talk between Hedgehog/SMO and AKT/GLI2 pathways in stromal fibroblasts.
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http://dx.doi.org/10.1101/gad.283499.116DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5066238PMC
September 2016

Cognitive impairment and gray matter volume abnormalities in silent cerebral infarction.

Neuroreport 2015 Oct;26(15):890-5

aDepartment of Neurology bBiomedical Engineering Laboratory cDepartment of Radiology dDepartment of Neurosurgery, the First Affiliated Hospital of Yangtze University, Hubei, Jingzhou, People's Republic of China.

To investigate the association between cognitive impairment and gray matter volume (GMV) abnormalities in silent cerebral infarction (SCI) patients, the GMV of 62 pairs of patients and well-matched healthy controls was calculated. All participants underwent a P300 test, a Montreal Cognitive Assessment (MoCA) test. Compared with controls, the patients showed decreased GMV in the left superior frontal gyrus, left inferior frontal gyrus, left superior temporal gyrus, right middle temporal gyrus, and bilateral parahippocampal gyrus; no significantly increasing GMV was found. The volumes of the frontal and temporal lobes were positively correlated with the score of the MoCA scale and P300 amplitudes (r≥0.62, P<0.01). The P300 latency was negatively correlated with the volumes of the frontal lobe, the temporal lobe, and the hippocampus (r≤-0.71, P<0.05). No significant correlations between the GMV of the abnormal brain regions and four clinical characteristics in SCI patients were found, suggesting that cognitive deficiency existed in SCI patients and the reduced GMV might contribute to the pathology of cognitive deficiency in SCI patients.
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http://dx.doi.org/10.1097/WNR.0000000000000443DOI Listing
October 2015