Publications by authors named "Lei Ren"

332 Publications

The Impact of Locomotor Speed on the Human Metatarsophalangeal Joint Kinematics.

Front Bioeng Biotechnol 2021 20;9:644582. Epub 2021 Apr 20.

Key Laboratory of Bionic Engineering, Ministry of Education, Jilin University, Changchun, China.

This paper aims to further our previous study to investigate the effect of speed on the human metatarsophalangeal (MP) joint kinematics during running on level ground. The 3D motion of the foot segments was captured by a twelve-camera motion analysis system, and the ground reaction forces and moments were recorded by using a six-force plate array. The relative movement between the tarsometatarsi (hindfoot) and phalanges (forefoot) segments were recorded to obtain the 3D orientation and position of the functional axis (FA) of the MP joint. The results show that the FA locates about an average of 19% foot length (FL) anterior to the anatomical axis (AA) across all running speeds, and is also 4.8% FL inferior to the AA during normal and fast run. Similar to walking, the functional axis is more oblique than the anatomical axis with a more anterior-inferior orientation across all the running speeds. This suggests that representing MP joint with the AA may mislead the calculation of joint moment/power and muscle moment arms in both running and walking gait. Compared with previous study, we found that walking and running speeds have statistically significant effects on the position of the FA. The functional axis moves frontward to a more anterior position when the speed increases during walking and running. It transfers upward in the superior direction with increasing speed of walking, but moves more toward the inferior position when the velocity increased further to running. Also, the orientation of FA in sagittal plane became more oblique toward the vertical direction as the speed increased. This may help in moderating the muscular effort, increase the muscle EMA and improve the locomotor performance. These results would contribute to understanding the in vivo biomechanical function of the MP joint and also the foot propulsion during human locomotion.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fbioe.2021.644582DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8093456PMC
April 2021

Hoof Pressure Distribution Pattern of Blue Sheep During Walking on Different Slopes: A Subject-Specific Analysis.

Front Vet Sci 2021 9;8:633509. Epub 2021 Apr 9.

Key Laboratory of Bionic Engineering, Jilin University, Changchun, China.

The purpose of this study was to quantitatively assess the vertical force distribution (VFD) of subject-specific healthy blue sheep while walking on different slopes using a pressure-sensing walkway. The blue sheep was trained to walk over the pressure-sensing walkway by choosing a comfortable walking speed, and the slope angle increased from 0° to 25°. The sheep's hooves were divided into four quadrants, namely, the cranio-lateral, cranio-medial, caudo-lateral, and caudo-medial quadrants, to investigate the VFD of the peak vertical force (PVF), vertical impulse (VI) and occurrence time of the PVF during the stance phase (TPVF). This study demonstrates that the main stressed quadrant of the front hoof changes from the caudo-medial quadrant to the cranio-medial quadrant with increasing slope. The main stressed quadrant of the rear hoof is the cranio-medial quadrant and does not change with the increasing slope. For all the slopes, the vertical force shifted from the lateral quadrant to the medial quadrant and from the caudal quadrant to the cranial quadrant. All the results obtained in the study suggest the feasibility of detecting gait changes in blue sheep, which has potential for the diagnosis of lower limb musculoskeletal diseases in quadrupeds.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fvets.2021.633509DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8062745PMC
April 2021

Nanoliquid Dressing with Enhancing Anti-Infection Performance under the Moderate Photothermal Effect for Wound Treatment.

ACS Appl Mater Interfaces 2021 Apr 13;13(16):18443-18453. Epub 2021 Apr 13.

Department of Biomaterials, College of Materials, Xiamen University, Xiamen 361005, People's Republic of China.

Nonhealing wounds have become a major healthcare burden worldwide. Chronic wound healing is universally hampered by the presence of bacterial infections that form biofilms. Therefore, in this study, a novel nanoliquid dressing based on a mild photothermal heating strategy was designed to provide safe healing of biofilm-infected wounds. Dilute nitric acid (HNO) solution was employed to induce a redox process triggered by copper sulfide (CuS) nanoplates in the nanoliquid dressing. This redox process was further promoted by the mild photothermal effect (≤47.5 °C) that generated a sufficient amount of reactive oxygen species, resulting in less thermal injury to normal tissues. Correspondingly, with the safe concentration of CuS nanoplates (0.4 mg/mL), excellent bactericidal efficiencies up to 98.3 and 99.3% against ampicillin-resistant () and () were achieved, respectively. Moreover, the nanoliquid dressing exhibited a near-infrared enhanced destructive effect on mature biofilms. According to wound healing experiments in mice, the nanoliquid dressing increased the healing rate and reduced the inflammatory response. This study provides a novel insight into treating the biofilm-infected chronic wounds in the "post-antibiotic era".
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acsami.0c21854DOI Listing
April 2021

Bioengineered bacteria-derived outer membrane vesicles as a versatile antigen display platform for tumor vaccination via Plug-and-Display technology.

Nat Commun 2021 04 6;12(1):2041. Epub 2021 Apr 6.

CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety & CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology of China, Zhongguancun, Beijing, China.

An effective tumor vaccine vector that can rapidly display neoantigens is urgently needed. Outer membrane vesicles (OMVs) can strongly activate the innate immune system and are qualified as immunoadjuvants. Here, we describe a versatile OMV-based vaccine platform to elicit a specific anti-tumor immune response via specifically presenting antigens onto OMV surface. We first display tumor antigens on the OMVs surface by fusing with ClyA protein, and then simplify the antigen display process by employing a Plug-and-Display system comprising the tag/catcher protein pairs. OMVs decorated with different protein catchers can simultaneously display multiple, distinct tumor antigens to elicit a synergistic antitumour immune response. In addition, the bioengineered OMVs loaded with different tumor antigens can abrogate lung melanoma metastasis and inhibit subcutaneous colorectal cancer growth. The ability of the bioengineered OMV-based platform to rapidly and simultaneously display antigens may facilitate the development of these agents for personalized tumour vaccines.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41467-021-22308-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8024398PMC
April 2021

Towards Improving the Quality of Electrophysiological Signal Recordings by Using Microneedle Electrode Arrays.

IEEE Trans Biomed Eng 2021 Apr 2;PP. Epub 2021 Apr 2.

Electrophysiological signals are recorded generally by metal electrodes placed on body surface. For long term use, the signal quality may decay with the change of interface impedance between electrodes and skin due to the conductive hydrogel dehydration. Besides, electrodes may shift during body movements, which causes unstable signal recordings. To improve the quality of electrophysiological signal recordings on human body surface, in this work, a type of microneedle electrode array (MEA) with microneedles around 550 m in length was fabricated with a magnetization-induce self-assembly method. The experiments showed that compared with the commonly used dry electrode array, the MEA has lower and more stable interface impedance, especially when the electrode-skin interface is under unstable pressures. For electrophysiological signal recording, the MEA can acquire electromyography (EMG) with significantly lower noise energy, higher signal-to-noise ratio, and higher motion-classification accuracy based on the EMG pattern-recognition method. Additionally, high quality electrocardiography (ECG) can be recorded by using the MEA, where more accurate R-peaks are extracted in different scenarios. Besides, there was no report about any discomfort like bleeding or inflammation by all the subjects. These findings suggest that the microneedles on the MEA can penetrate through the corneum and reach the epidermis of the subjects, which could avoid the influence of corneum and fix the electrode on the body surface for high-quality signal recording especially during body movements. Furthermore, the microneedles would not touch the dermis, enabling a painless signal acquisition, which is beneficial to the applications of wearable human-machine interface technology.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1109/TBME.2021.3070541DOI Listing
April 2021

A bifunctional enzyme belonging to cytochrome P450 family involved in the O-dealkylation and N-dealkoxymethylation toward chloroacetanilide herbicides in Rhodococcus sp. B2.

Microb Cell Fact 2021 Mar 4;20(1):61. Epub 2021 Mar 4.

Eco-Environmental Protection Research Institute, Shanghai Academy of Agricultural Sciences, Shanghai, 201403, People's Republic of China.

Background: The chloroacetamide herbicides pretilachlor is an emerging pollutant. Due to the large amount of use, its presence in the environment threatens human health. However, the molecular mechanism of pretilachlor degradation remains unknown.

Results: Now, Rhodococcus sp. B2 was isolated from rice field and shown to degrade pretilachlor. The maximum pretilachlor degradation efficiency (86.1%) was observed at a culture time of 5 d, an initial substrate concentration 50 mg/L, pH 6.98, and 30.1 °C. One novel metabolite N-hydroxyethyl-2-chloro-N-(2, 6-diethyl-phenyl)-acetamide was identified by gas chromatography-mass spectrometry (GC-MS). Draft genome comparison demonstrated that a 32,147-bp DNA fragment, harboring gene cluster (EthRABCD), was absent from the mutant strain TB2 which could not degrade pretilachlor. The Eth gene cluster, encodes an AraC/XylS family transcriptional regulator (EthR), a ferredoxin reductase (EthA), a cytochrome P450 monooxygenase (EthB), a ferredoxin (EthC) and a 10-kDa protein of unknown function (EthD). Complementation with EthABCD and EthABD, but not EthABC in strain TB2 restored its ability to degrade chloroacetamide herbicides. Subsequently, codon optimization of EthABCD was performed, after which the optimized components were separately expressed in Escherichia coli, and purified using Ni-affinity chromatography. A mixture of EthABCD or EthABD but not EthABC catalyzed the N-dealkoxymethylation of alachlor, acetochlor, butachlor, and propisochlor and O-dealkylation of pretilachlor, revealing that EthD acted as a ferredoxin in strain B2. EthABD displayed maximal activity at 30 °C and pH 7.5.

Conclusions: This is the first report of a P450 family oxygenase catalyzing the O-dealkylation and N-dealkoxymethylation of pretilachlor and propisochlor, respectively. And the results of the present study provide a microbial resource for the remediation of chloroacetamide herbicides-contaminated sites.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s12934-021-01544-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7934444PMC
March 2021

Camouflaged Gold Nanodendrites Enable Synergistic Photodynamic Therapy and NIR Biowindow II Photothermal Therapy and Multimodal Imaging.

ACS Appl Mater Interfaces 2021 Mar 1;13(9):10778-10795. Epub 2021 Mar 1.

Department of Chemistry and Chemical Biology, Stevens Institute of Technology, Hoboken, New Jersey 07030, United States.

Gold nanodendrite (AuND)-based nanotheranostic agents with versatile capabilities were fabricated by optimizing the geometrical configurations (dendrite length and density) of AuND to achieve localized surface plasmon resonance (LSPR) in near-infrared biowindow II (NIR-II), and then subsequently functionalizing with a mitochondria-targeting compound (triphenylphosphonium, TPP), loading with an NIR-photosensitizer (indocyanine green, ICG) and coating with the macrophage cell membrane (MCM) to trap ICG within AuND and selectively interact with MDA-MB-231 cells. The novel AuND-TPP-ICG@MCM system enabled the integration of multimodal fluorescence/photoacoustic/surface-enhanced Raman imaging with synergistic therapies of NIR-II photothermal therapy and NIR-I photodynamic therapy for cancer treatment. Enhanced hyperthermia and elevated production of reactive oxygen species within the tumors MCM coating and mitochondria targeting afforded a synergistic efficacy for tumor eradication with limited side effects. The demonstrated biocompatibility, multi-imaging capability, and high therapeutic efficiency under NIR laser irradiation indicate the potentials of this multifunctional nanotheranostic platform for clinical utility in cancer therapy.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acsami.1c01238DOI Listing
March 2021

Gyroscope Sensor Based Finger Axes of Rotation Identification Using Screw Displacement.

Appl Bionics Biomech 2021 10;2021:8871593. Epub 2021 Feb 10.

School of Mechatronics Engineering and Automation, National University of Defence Technology, 410073, China.

This paper presents a low-cost, efficient, and portable method for identifying axes of rotation of the proximal interphalangeal and distal interphalangeal joints in an index finger. The approach is associated with the screw displacement representation of rigid body motion. Using the matrix exponential method, a detailed derivation of general spatial displacement of a rigid body in the form of screw displacement including the Rodrigues' formulae for rotation is presented. Then, based on a gyroscope sensor, a test framework for determining axes of rotation of finger joints is established, and experiments on finding the directions of joint axes of the PIP and DIP joints are conducted. The results obtained highly agree with those presented in literature through traditional but complex methods.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1155/2021/8871593DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7892214PMC
February 2021

Surrogate models based on machine learning methods for parameter estimation of left ventricular myocardium.

R Soc Open Sci 2021 Jan 13;8(1):201121. Epub 2021 Jan 13.

School of Mathematics and Statistics, University of Glasgow, Glasgow G12 8QQ, UK.

A long-standing problem at the frontier of biomechanical studies is to develop fast methods capable of estimating material properties from clinical data. In this paper, we have studied three surrogate models based on machine learning (ML) methods for fast parameter estimation of left ventricular (LV) myocardium. We use three ML methods named K-nearest neighbour (KNN), XGBoost and multi-layer perceptron (MLP) to emulate the relationships between pressure and volume strains during the diastolic filling. Firstly, to train the surrogate models, a forward finite-element simulator of LV diastolic filling is used. Then the training data are projected in a low-dimensional parametrized space. Next, three ML models are trained to learn the relationships of pressure-volume and pressure-strain. Finally, an inverse parameter estimation problem is formulated by using those trained surrogate models. Our results show that the three ML models can learn the relationships of pressure-volume and pressure-strain very well, and the parameter inference using the surrogate models can be carried out in minutes. Estimated parameters from both the XGBoost and MLP models have much less uncertainties compared with the KNN model. Our results further suggest that the XGBoost model is better for predicting the LV diastolic dynamics and estimating passive parameters than other two surrogate models. Further studies are warranted to investigate how XGBoost can be used for emulating cardiac pump function in a multi-physics and multi-scale framework.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1098/rsos.201121DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7890479PMC
January 2021

Respiratory deformation registration in 4D-CT/cone beam CT using deep learning.

Quant Imaging Med Surg 2021 Feb;11(2):737-748

Department of Radiation Oncology, Duke University Medical Center, Durham, NC, USA.

Background: To investigate the feasibility of using a supervised convolutional neural network (CNN) to register phase-to-phase deformable vector field of lung 4D-CT/4D-cone beam CT for 4D dose accumulation, contour propagation, motion modeling, or target verification.

Methods: We built a CNN-based deep learning method to register the deformation field directly between phases of patients' 4D-CT or 4D-cone beam CT. The input consists of patch pairs of two phases, while the output is the corresponding deformation field that registers the patch pairs. The centers of the patch pairs were uniformly sampled across the lung, and the size of the patches was chosen to cover the range of the respiratory motion. The network was trained to generate deformation field that matches with the reference deformation field generated by VelocityAI (Varian). The network is structured with four convolutional layers, two average pooling layers, and two fully connected layers. Half mean squared error is applied to guide the study as loss function. Nine patients with eleven sets of 4D-CT/cone beam CT image volumes were used for training and testing. The performance of the network was validated with intra-patient and inter-patient setups.

Results: Registered images were generated with Velocity deformation field and the CNN deformation field, respectively. Main anatomic features such as the main vessels and the diaphragm matched well between two deformed images. In the diaphragm region, the coefficients of cross-correlation, root mean squared error, and structural similarity index measure (SSIM) between deformed images registered by CNN and VelocityAI was calculated. The cross-correlation was above 0.9 for all the intra-patient cases.

Conclusions: Patch-based deep learning methods achieved comparable deformable registration accuracy as VelocityAI. Compared to VelocityAI, the deep learning method is fully automatic and faster without user dependency, which makes it more preferable in clinical applications.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.21037/qims-19-1058DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7779910PMC
February 2021

Building a patient-specific model using transfer learning for four-dimensional cone beam computed tomography augmentation.

Quant Imaging Med Surg 2021 Feb;11(2):540-555

Department of Radiation Oncology, Duke University Medical Center (DUMC), Durham, North Carolina, USA.

Background: We previously developed a deep learning model to augment the quality of four-dimensional (4D) cone-beam computed tomography (CBCT). However, the model was trained using group data, and thus was not optimized for individual patients. Consequently, the augmented images could not depict small anatomical structures, such as lung vessels.

Methods: In the present study, the transfer learning method was used to further improve the performance of the deep learning model for individual patients. Specifically, a U-Net-based model was first trained to augment 4D-CBCT using group data. Next, transfer learning was used to fine tune the model based on a specific patient's available data to improve its performance for that individual patient. Two types of transfer learning were studied: layer-freezing and whole-network fine-tuning. The performance of the transfer learning model was evaluated by comparing the augmented CBCT images with the ground truth images both qualitatively and quantitatively using a structure similarity index matrix (SSIM) and peak signal-to-noise ratio (PSNR). The results were also compared to those obtained using only the U-Net method.

Results: Qualitatively, the patient-specific model recovered more detailed information of the lung area than the group-based U-Net model. Quantitatively, the SSIM improved from 0.924 to 0.958, and the PSNR improved from 33.77 to 38.42 for the whole volumetric images for the group-based U-Net and patient-specific models, respectively. The layer-freezing method was found to be more efficient than the whole-network fine-tuning method, and had a training time as short as 10 minutes. The effect of augmentation by transfer learning increased as the number of projections used for CBCT reconstruction decreased.

Conclusions: Overall, the patient-specific model optimized by transfer learning was efficient and effective at improving image qualities of augmented undersampled three-dimensional (3D)- and 4D-CBCT images, and could be extremely valuable for applications in image-guided radiation therapy.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.21037/qims-20-655DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7779907PMC
February 2021

Photoacoustic molecular imaging-escorted adipose photodynamic-browning synergy for fighting obesity with virus-like complexes.

Nat Nanotechnol 2021 Apr 1;16(4):455-465. Epub 2021 Feb 1.

State Key Laboratory of Molecular Vaccinology and Molecular Diagnosis & Center for Molecular Imaging and Translational Medicine, School of Public Health, Xiamen University, Xiamen, China.

Photodynamic therapy and adipose browning induction are two promising approaches to reverse obesity. The former strategy acts rapidly and locally, whereas the latter has a more gradual and widespread effect. Despite their complementarity, they have rarely been combined and imaged non-invasively in vivo. Here we introduce an adipose-targeting hepatitis B core protein complex that contains a traceable photosensitizer (ZnPcS (zinc phthalocyanine tetrasulfonate)) and a browning agent (rosiglitazone) that allows simultaneous photodynamic and browning treatments, with photoacoustic molecular imaging. After intravenous injection in obese mice, the complex binds specifically to white adipose tissues, especially those rich in blood supply, and drives adipose reduction thanks to the synergy of ZnPcS photodynamics and rosiglitazone browning. Using photoacoustic molecular imaging, we could monitor the changes induced by the treatment, which included complex activity, lipid catabolism and angiogenesis. Our findings demonstrate the anti-obesity potential of our feedback-based synergic regimen orchestrated by the targeted hepatitis B core complex.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41565-020-00844-6DOI Listing
April 2021

Effects of two ecological earthworm species on tetracycline degradation performance, pathway and bacterial community structure in laterite soil.

J Hazard Mater 2021 Jun 23;412:125212. Epub 2021 Jan 23.

School of Environment, Tsinghua University, Beijing 100084, PR China. Electronic address:

This study explored the change of tetracycline degradation efficiency, metabolic pathway, soil physiochemical properties and degraders in vermiremediation by two earthworm species of epigeic Eisenia fetida and endogeic Amynthas robustus. We found a significant acceleration of tetracycline degradation in both earthworm treatments, and 4-epitetracycline dehydration pathway was remarkably enhanced only by vermiremediation. Tetracycline degraders from soils, earthworm intestines and casts were different. Ralstonia and Sphingomonas were potential tetracycline degraders in soils and metabolized tetracycline through direct dehydration pathway. Degraders in earthworm casts (Comamonas, Acinetobacter and Stenotrophomonas) and intestines (Pseudomonas and Arthrobacter) dehydrated 4-epitetracycline into 4-epianhydrotetracycline. More bacterial lineages resisting tetracycline were found in earthworm treatments, indicating the adaptation of soil and intestinal flora under tetracycline pressure. Earthworm amendment primarily enhanced tetracycline degradation by neutralizing soil pH and consuming organic matters, stimulating both direct dehydration and epimerization-dehydration pathways. Our findings proved that vermicomposting with earthworms is effective to alter soil microenvironment and accelerate tetracycline degradation, behaving as a potential approach in soil remediation at tetracycline contaminated sites.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jhazmat.2021.125212DOI Listing
June 2021

Dissecting Efficacy and Metabolic Characteristic Mechanism of on Renal Fibrosis by Multivariate Approach and Ultra-Performance Liquid Chromatography Coupled With Mass Spectrometry-Based Metabolomics Strategy.

Front Pharmacol 2020 14;11:608511. Epub 2021 Jan 14.

Department of Clinical Laboratory, Affiliated Hospital of Guilin Medical University, Guangxi, China.

Taxifolin (TFN) is an important natural compound with antifibrotic activity; however, its pharmacological mechanism is not clear. In this study, our aim is to gain insight into the effects of TFN and its potential mechanisms in unilateral ureteral obstruction (UUO) animal model using metabolomics approach to identify the metabolic biomarkers and perturbed pathways. Serum metabolomics analysis by UPLC-Q-TOF/MS was carried out to discover the changes in the metabolic profile. It showed that TFN has a significant protective effect on UUO-induced renal fibrosis and a total of 32 potential biomarkers were identified and related to RF progression. Of note, 27 biomarkers were regulated by TFN treatment, which participate in eight metabolic pathways, including phenylalanine, tyrosine and tryptophan biosynthesis, and phenylalanine metabolism. It also showed that metabolomics was a promising strategy to better dissect metabolic characteristics and pharmacological mechanisms of natural compounds by multivariate approach and ultra-performance liquid chromatography coupled with mass spectrometry.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fphar.2020.608511DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7841412PMC
January 2021

Simulation Analysis of Impulsive Ankle Push-Off on the Walking Speed of a Planar Biped Robot.

Front Bioeng Biotechnol 2020 12;8:621560. Epub 2021 Jan 12.

Key Laboratory of Bionic Engineering, Jilin University, Changchun, China.

Ankle push-off generates more than 80% positive power at the end of the stance phase during human walking. In this paper, the influence of impulsive ankle push-off on the walking speed of a biped robot is studied by simulation. When the push-off height of the ankle joint is 13 cm based on the ground (the height of the ankle joint of the swing leg) and the ankle push-off torque increases from 17 to 20.8 N·m, the duration of the swinging leg actually decreases from 50 to 30% of the gait cycle, the fluctuation amplitude of the COM (center of mass) instantaneous speed of the robot decreases from 95 to 35% of the maximum speed, and the walking speed increases from 0.51 to 1.14 m/s. The results demonstrate that impulsive ankle push-off can effectively increase the walking speed of the planar biped robot by accelerating the swing leg and reducing the fluctuation of the COM instantaneous speed. Finally, a comparison of the joint kinematics of the simulation robot and the human at a normal walking speed shows similar motion patterns.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fbioe.2020.621560DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7835415PMC
January 2021

Preparation and preliminary evaluation of hepatitis B core antigen virus like nanoparticles loaded with indocyanine green.

Ann Transl Med 2020 Dec;8(24):1661

Henan Bioengineering Research Center, Zhengzhou, China.

Background: In recent years, nanotechnology has attracted a plethora of attention due of its ability to effectively diagnose and treat various tumors. Virus-like particles (VLPs) have good biocompatibility, are safe and non-toxic, and have an internal hollow space, and as such they are often used as nano drug carriers. In recent years, it has become one of the hot spots in the field of biopharmaceutical engineering.

Methods: In this study, the tumor-targeting peptide RGD (Arg-Gly-Asp) was genetically inserted into the major immunodominant region (MIR) of the hepatitis B virus core protein (HBc). A series of characterization, including stability and optical properties, were evaluated. A visual diagnosis and analysis of the efficacy against tumor cells were conducted at the cell level and using a live animal model.

Results: This study demonstrated that the recombinant HBc-based VLPs could participate in self-assembly of monodispersed nanoparticles with well-defined morphology, and the near-infrared dye indocyanine green (ICG) could be packaged into the VLPs without any chemical modification. Moreover, the HBc-based VLPs could specifically target cancer cells via the interaction with overexpressed integrin αvβ3. The treatment with ICG-loaded HBc-based VLPs showed significant inhibition of 4T1 breast cancer cell growth (84.87% tumor growth inhibition). The imaging experiments demonstrated that the ICG-loaded HBc-based VLPs generated excellent fluorescence in tumor sites in 4T1 breast cancer bearing mice. This provided crucial information on tumor mass location, boundaries, and shape. Moreover, compared to free ICG, the nanosystem showed significantly longer blood circulation time and superior accuracy in targeting the tumor.

Conclusions: The ICG-loaded HBc-based VLPs prepared in this study were of good stability and biocompatibility. It showed strong tumor targeting specificity and tumor visualization. Thus, it is expected to provide a new experimental basis and theoretical support for the integration of VLPs in the clinical diagnosis and treatment of breast cancer.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.21037/atm-20-7478DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7812214PMC
December 2020

Frictional performance of ostrich (Struthio camelus) foot sole on sand in all directions.

Biomech Model Mechanobiol 2021 Apr 22;20(2):671-681. Epub 2021 Jan 22.

China North Vehicle Research Institute, Beijing, 100072, People's Republic of China.

To study the ostrich (Struthio camelus) foot sole with an irregular surface and papillae, we designed a multi-angle device to measure its friction properties on sand. The observed macro- and micro-structures of the ostrich foot sole intensified friction by tightly gripping sand particles. The sliding friction of the ostrich foot on a single-layer sand board increased with the enlarging particle size. A loose sand all-direction test showed that the coefficient of friction (COF) of the ostrich foot sole was higher than that of the nonpapillary foot. The COF of the ostrich foot sole minimized to 0.30 at 0° and maximized to 0.61 at 180°, and that of the nonpapillary foot minimized to 0.23 at 300° and maximized to 0.54 at 180°, suggesting the ostrich papillae exerted a friction effect. Significant differences in COF were observed among the ranges 10°-40°, 90° and 120°-350°, indicating the papillae can steadily enhance the frictional performance. This study provides an important theoretical basis for the design of frictional robots for deep space exploration and other soft media.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s10237-020-01409-1DOI Listing
April 2021

Laboratory Evaluation of Fluidity of Heavy Oil Emulsions in Formation Pores Medium.

ACS Omega 2021 Jan 24;6(1):623-632. Epub 2020 Dec 24.

Research Institute of Petroleum Exploration and Development, Beijing 100083, China.

Heavy oil emulsions such as water in oil (W/O), oil in water (O/W), and water in oil in water (W/O/W) would be formed during the development of heavy oil reservoirs. The key to the efficient development of heavy oil reservoirs is to clarify the fluidity of heavy oil emulsions in formation pores medium. In this study, the main factors that determine the fluidity of heavy oil emulsion were analyzed under the condition of simulating the formation pores medium. The reasons for the difference between the viscosity of heavy oil emulsions in formation pores medium and the viscosity measured by laboratory rheometer were analyzed. Then, experiments have confirmed the shortcomings of the current screening and evaluation method of emulsified viscosity reducer. Finally, through experimental research and mechanism analysis, the mechanism of the emulsified viscosity reducer was studied and suggestions were made to improve the effect of emulsified viscosity reducer in the oil field. When heavy emulsions flow in a formation pores medium, since the size of the droplets would be larger than the size of the pores medium, when the heavy emulsion passes through the pores medium, it would receive additional resistance brought by the Jiamin effect. But when a rheometer is used for viscosity testing, this additional resistance is almost nonexistent. Therefore, the current method of viscosity test using rheometer cannot fully reflect the actual flow state of heavy oil emulsion in formation pores medium. The research in this paper proves that the larger the droplets of the emulsion, the less accurate the rheometer test results. Temperature, permeability, oil-water ratio, and the type of emulsified viscosity reducer all have a certain effect on the flow of heavy oil emulsion in formation pores medium. This article evaluated four types of emulsified viscosity reducers. When the viscosity test was performed by a rheometer, the results showed excellent viscosity-reducing effects. However, when simulating formation pores medium conditions, the effects of some types of emulsified viscosity reducers are not so good. It is no longer accurate to judge the effect of emulsified viscosity reducer by the way of measuring viscosity with a rheometer. It should be screened by the flow capacity of the heavy oil emulsions in formation pores medium. In oil field development, the contact area of heavy oil and emulsified viscosity reducer solution should be increased as much as possible and provide more time for the substitution effect of emulsified viscosity reducer molecules.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acsomega.0c05148DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7807747PMC
January 2021

Regulation of Autophagy Orchestrates Pyroptotic Cell Death in Molybdenum Disulfide Quantum Dot-Induced Microglial Toxicity.

ACS Biomater Sci Eng 2020 03 24;6(3):1764-1775. Epub 2020 Feb 24.

Department of Biomaterials, Research Center of Biomedical Engineering of Xiamen & Key Laboratory of Biomedical Engineering of Fujian Province, College of Materials, Xiamen University, Xiamen 361005, P. R. China.

Molybdenum disulfide quantum dots (MoS QDs) represent an emerging class of two-dimensional (2D) atomically layered transition metal dichalcogenide nanostructures with few nanometers in lateral size, which show attractive potential as versatile platforms for theranostic applications in various neurological disorders. However, the potential impacts of MoS QDs on microglia remain unclear. In this report, we showed that exposure of microglia to MoS QDs triggered NLRP3 inflammasome activation as revealed by the cleavage of the inactive precursor of caspase-1 to its active form and the increased release of downstream pro-inflammatory cytokines, resulting in microglia cell death that occurred through caspase-1-dependent pyroptosis. We also found that MoS QDs activated autophagy, and suppression of autophagy by specific inhibitors potentiated MoS QD-induced pyroptosis. Additionally, MoS QDs stimulated mitochondria-derived reactive oxygen species (mtROS) generation in BV-2 cells. However, ROS scavengers could diminish the MoS QD-mediated NLRP3 inflammasome activation and pyroptotic cell death in microglia. Overall, our findings identified pyroptosis as a cellular response to MoS QD exposure in microglial cells, affording novel insights into the neurotoxicity of MoS QDs and facilitating the rational design and application of functional MoS QDs in neuroscience.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acsbiomaterials.9b01932DOI Listing
March 2020

Design of Decision Tree Structure with Improved BPNN Nodes for High-Accuracy Locomotion Mode Recognition Using a Single IMU.

Sensors (Basel) 2021 Jan 13;21(2). Epub 2021 Jan 13.

Key Laboratory of Bionic Engineering, Ministry of Education, Jilin University, Changchun 130000, China.

Smart wearable robotic system, such as exoskeleton assist device and powered lower limb prostheses can rapidly and accurately realize man-machine interaction through locomotion mode recognition system. However, previous locomotion mode recognition studies usually adopted more sensors for higher accuracy and effective intelligent algorithms to recognize multiple locomotion modes simultaneously. To reduce the burden of sensors on users and recognize more locomotion modes, we design a novel decision tree structure (DTS) based on using an improved backpropagation neural network (IBPNN) as judgment nodes named IBPNN-DTS, after analyzing the experimental locomotion mode data using the original values with a 200-ms time window for a single inertial measurement unit to hierarchically identify nine common locomotion modes (level walking at three kinds of speeds, ramp ascent/descent, stair ascent/descent, Sit, and Stand). In addition, we reduce the number of parameters in the IBPNN for structure optimization and adopted the artificial bee colony (ABC) algorithm to perform global search for initial weight and threshold value to eliminate system uncertainty because randomly generated initial values tend to result in a failure to converge or falling into local optima. Experimental results demonstrate that recognition accuracy of the IBPNN-DTS with ABC optimization (ABC-IBPNN-DTS) was up to 96.71% (97.29% for the IBPNN-DTS). Compared to IBPNN-DTS without optimization, the number of parameters in ABC-IBPNN-DTS shrank by 66% with only a 0.58% reduction in accuracy while the classification model kept high robustness.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/s21020526DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7828453PMC
January 2021

Patterns and Relevance of Langerhans Islet Invasion in Pancreatic Cancer.

Cancers (Basel) 2021 Jan 11;13(2). Epub 2021 Jan 11.

Department of Surgery, Klinikum Rechts der Isar, Technical University of Munich, Ismaninger Str. 22, D-81675 Munich, Germany.

: Pancreatic cancer-associated diabetes mellitus (PC-DM) is present in most patients with pancreatic cancer, but its pathogenesis remains poorly understood. Therefore, we aimed to characterize tumor infiltration in Langerhans islets in pancreatic cancer and determine its clinical relevance.

Methods: Langerhans islet invasion was systematically analyzed in 68 patientswith pancreatic ductal adenocarcinoma (PDAC) using histopathological examination and 3D in vitro migration assays were performed to assess chemoattraction of pancreatic cancer cells to isletcells.

Results: Langerhans islet invasion was present in all patients. We found four different patterns of islet invasion: (Type I) peri-insular invasion with tumor cells directly touching the boundary, but not penetrating the islet; (Type II) endo-insular invasion with tumor cells inside the round islet; (Type III) distorted islet structure with complete loss of the round islet morphology; and (Type IV)adjacent cancer and islet cells with solitary islet cells encountered adjacent to cancer cells. Pancreatic cancer cells did not exhibit any chemoattraction to islet cells in 3D assays in vitro. Further, there was no clinical correlation of islet invasion using the novel Islet Invasion Severity Score (IISS), which includes all invasion patterns with the occurrence of diabetes mellitus. However, Type IV islet invasion was related to worsened overall survival in our cohort.

Conclusions: We systematically analyzed, for the first time, islet invasion in human pancreatic cancer. Four different main patterns of islet invasion were identified. Diabetes mellitus was not related to islet invasion. However, moreresearch on this prevailing feature of pancreatic cancer is needed to better understand underlying principles.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/cancers13020249DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7826785PMC
January 2021

A deep learning framework for F-FDG PET imaging diagnosis in pediatric patients with temporal lobe epilepsy.

Eur J Nucl Med Mol Imaging 2021 Jan 9. Epub 2021 Jan 9.

Department of Nuclear Medicine and PET-CT Center, The Second Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang, China.

Purpose: Epilepsy is one of the most disabling neurological disorders, which affects all age groups and often results in severe consequences. Since misdiagnoses are common, many pediatric patients fail to receive the correct treatment. Recently, F-fluorodeoxyglucose positron emission tomography (F-FDG PET) imaging has been used for the evaluation of pediatric epilepsy. However, the epileptic focus is very difficult to be identified by visual assessment since it may present either hypo- or hyper-metabolic abnormality with unclear boundary. This study aimed to develop a novel symmetricity-driven deep learning framework of PET imaging for the identification of epileptic foci in pediatric patients with temporal lobe epilepsy (TLE).

Methods: We retrospectively included 201 pediatric patients with TLE and 24 age-matched controls who underwent F-FDG PET-CT studies. F-FDG PET images were quantitatively investigated using 386 symmetricity features, and a pair-of-cube (PoC)-based Siamese convolutional neural network (CNN) was proposed for precise localization of epileptic focus, and then metabolic abnormality level of the predicted focus was calculated automatically by asymmetric index (AI). Performances of the proposed framework were compared with visual assessment, statistical parametric mapping (SPM) software, and Jensen-Shannon divergence-based logistic regression (JS-LR) analysis.

Results: The proposed deep learning framework could detect the epileptic foci accurately with the dice coefficient of 0.51, which was significantly higher than that of SPM (0.24, P < 0.01) and significantly (or marginally) higher than that of visual assessment (0.31-0.44, P = 0.005-0.27). The area under the curve (AUC) of the PoC classification was higher than that of the JS-LR (0.93 vs. 0.72). The metabolic level detection accuracy of the proposed method was significantly higher than that of visual assessment blinded or unblinded to clinical information (90% vs. 56% or 68%, P < 0.01).

Conclusion: The proposed deep learning framework for F-FDG PET imaging could identify epileptic foci accurately and efficiently, which might be applied as a computer-assisted approach for the future diagnosis of epilepsy patients.

Trial Registration: NCT04169581. Registered November 13, 2019 Public site: https://clinicaltrials.gov/ct2/show/NCT04169581.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00259-020-05108-yDOI Listing
January 2021

4D radiomics: impact of 4D-CBCT image quality on radiomic analysis.

Phys Med Biol 2021 Feb 11;66(4):045023. Epub 2021 Feb 11.

Department of Radiation Oncology, Duke University Medical Center, DUMC Box 3295, Durham, NC, 27710, United States of America. Medical Physics Graduate Program, Duke University, 2424 Erwin Road Suite 101, Durham, NC 27705, United States of America.

Purpose: To investigate the impact of 4D-CBCT image quality on radiomic analysis and the efficacy of using deep learning based image enhancement to improve the accuracy of radiomic features of 4D-CBCT.

Material And Methods: In this study, 4D-CT data from 16 lung cancer patients were obtained. Digitally reconstructed radiographs (DRRs) were simulated from the 4D-CT, and then used to reconstruct 4D CBCT using the conventional FDK (Feldkamp et al 1984 J. Opt. Soc. Am. A 1 612-9) algorithm. Different projection numbers (i.e. 72, 120, 144, 180) and projection angle distributions (i.e. evenly distributed and unevenly distributed using angles from real 4D-CBCT scans) were simulated to generate the corresponding 4D-CBCT. A deep learning model (TecoGAN) was trained on 10 patients and validated on 3 patients to enhance the 4D-CBCT image quality to match with the corresponding ground-truth 4D-CT. The remaining 3 patients with different tumor sizes were used for testing. The radiomic features in 6 different categories, including histogram, GLCM, GLRLM, GLSZM, NGTDM, and wavelet, were extracted from the gross tumor volumes of each phase of original 4D-CBCT, enhanced 4D-CBCT, and 4D-CT. The radiomic features in 4D-CT were used as the ground-truth to evaluate the errors of the radiomic features in the original 4D-CBCT and enhanced 4D-CBCT. Errors in the original 4D-CBCT demonstrated the impact of image quality on radiomic features. Comparison between errors in the original 4D-CBCT and enhanced 4D-CBCT demonstrated the efficacy of using deep learning to improve the radiomic feature accuracy.

Results: 4D-CBCT image quality can substantially affect the accuracy of the radiomic features, and the degree of impact is feature-dependent. The deep learning model was able to enhance the anatomical details and edge information in the 4D-CBCT as well as removing other image artifacts. This enhancement of image quality resulted in reduced errors for most radiomic features. The average reduction of radiomics errors for 3 patients are 20.0%, 31.4%, 36.7%, 50.0%, 33.6% and 11.3% for histogram, GLCM, GLRLM, GLSZM, NGTDM and Wavelet features. And the error reduction was more significant for patients with larger tumors. The findings were consistent across different respiratory phases, projection numbers, and angle distributions.

Conclusions: The study demonstrated that 4D-CBCT image quality has a significant impact on the radiomic analysis. The deep learning-based augmentation technique proved to be an effective approach to enhance 4D-CBCT image quality to improve the accuracy of radiomic analysis.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1088/1361-6560/abd668DOI Listing
February 2021

Indirect cholinergic activation slows down pancreatic cancer growth and tumor-associated inflammation.

J Exp Clin Cancer Res 2020 Dec 24;39(1):289. Epub 2020 Dec 24.

Department of Surgery, Klinikum rechts der Isar, Technical University of Munich, School of Medicine, Ismaninger Str. 22, 81675, Munich, Germany.

Background: Nerve-cancer interactions are increasingly recognized to be of paramount importance for the emergence and progression of pancreatic cancer (PCa). Here, we investigated the role of indirect cholinergic activation on PCa progression through inhibition of acetylcholinesterase (AChE) via clinically available AChE-inhibitors, i.e. physostigmine and pyridostigmine.

Methods: We applied immunohistochemistry, immunoblotting, MTT-viability, invasion, flow-cytometric-cell-cycle-assays, phospho-kinase arrays, multiplex ELISA and xenografted mice to assess the impact of AChE inhibition on PCa cell growth and invasiveness, and tumor-associated inflammation. Survival analyses were performed in a novel genetically-induced, surgically-resectable mouse model of PCa under adjuvant treatment with gemcitabine+/-physostigmine/pyridostigmine (n = 30 mice). Human PCa specimens (n = 39) were analyzed for the impact of cancer AChE expression on tumor stage and survival.

Results: We discovered a strong expression of AChE in cancer cells of human PCa specimens. Inhibition of this cancer-cell-intrinsic AChE via pyridostigmine and physostigmine, or administration of acetylcholine (ACh), diminished PCa cell viability and invasion in vitro and in vivo via suppression of pERK signaling, and reduced tumor-associated macrophage (TAM) infiltration and serum pro-inflammatory cytokine levels. In the novel genetically-induced, surgically-resectable PCa mouse model, adjuvant co-therapy with AChE blockers had no impact on survival. Accordingly, survival of resected PCa patients did not differ based on tumor AChE expression levels. Patients with higher-stage PCa also exhibited loss of the ACh-synthesizing enzyme, choline-acetyltransferase (ChAT), in their nerves.

Conclusion: For future clinical trials of PCa, direct cholinergic stimulation of the muscarinic signaling, rather than indirect activation via AChE blockade, may be a more effective strategy.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s13046-020-01796-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7758936PMC
December 2020

Programmable Transformation and Controllable Locomotion of Magnetoactive Soft Materials with 3D-Patterned Magnetization.

ACS Appl Mater Interfaces 2020 Dec 15;12(52):58179-58190. Epub 2020 Dec 15.

Guangdong Provincial Key Laboratory of Sensor Technology and Biomedical Instrument, School of Biomedical Engineering, Sun Yat-sen University, Guangzhou 510275 PR China.

Magnetoactive soft material (MASM) is distinguished for multifunctional shape manipulations under magnetic actuation, thereby holding a great promise in soft robotics, actuators, electronics, and metamaterials. However, the current research of MASM with continuum hard-magnetic profiles focuses little on the transformation mechanism, high dimensional shape transformation, and multistable locomotion. Herein, we developed a systematic methodology for programmable transformation and controllable locomotion of MASM with 3D-patterned continuum magnetization. An iterative computational model based on the equilibrium between magnetic torque and deformation-induced elastic torque was developed for precise prediction of MASM transformation. Multidimensional and complex shape manipulation ability of MASM was demonstrated by magnetically actuated transformations, including 1D to 2D, 2D to 3D, and 3D to 4D transformations of solid MASM, 2D to 3D pattern transformation of MASM-based elastin-like mesh, and 3D to 4D transformation of MASM-based cuboidal lattice. Multistable and controllable locomotion of MASM was verified by multimodal locomotion behaviors of a scallop-inspired robot for wall climbing in a dry frame and drug delivery in wet stomach, including roll, open, and close under self-locked and unlocked states.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acsami.0c15406DOI Listing
December 2020

Early diagnosis of diabetic peripheral neuropathy based on infrared thermal imaging technology.

Diabetes Metab Res Rev 2020 Dec 11:e3429. Epub 2020 Dec 11.

Key Laboratory of Bionic Engineering, Ministry of Education, Jilin University, Changchun, China.

Aims: The purpose of this study was to detect and compare the surface temperature of plantar vessels in mild diabetic peripheral neuropathy (DPN) patients and healthy controls, to explore a simple, convenient and reliable method for early diagnosis of DPN, and to explore the influence of sex and age on vascular surface temperature.

Materials And Methods: In this study, 60 mild DPN patients (30 males and 30 females) and 60 healthy volunteers were randomly recruited according to their age and sex. Intra-class correlation coefficient was used to evaluate the repeatability of skin temperature measurement in the vascular area. A general linear model was used to analyse the difference of skin temperature between mild DPN patients and healthy controls.

Results: The infrared detection results of skin temperature corresponding to blood vessels showed excellent test-retest reliability. There was no significant difference in skin temperature between sex and age. But there were significant differences in skin temperature between mild DPN patients and healthy controls, except for the posterior tibial artery.

Conclusions: For mild DNP patients, in case of no obvious abnormality in the infrared detection of lower extremity arterial surface temperature, the small vessels have shown early abnormal body surface temperature, that is, the surface temperature of related vessels increased. The research conclusions of this article not only enable us to better understand the correlation between body surface temperature and hemodynamic parameters, but also provide an in vivo, non-invasive, and convenient way of thinking and methods for early diagnosis of DPN.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/dmrr.3429DOI Listing
December 2020

Comparison of Incidence and Outcomes of Neuroblastoma in Children, Adolescents, and Adults in the United States: A Surveillance, Epidemiology, and End Results (SEER) Program Population Study.

Med Sci Monit 2020 Nov 29;26:e927218. Epub 2020 Nov 29.

Department of Neonatal Surgery, Children's Hospital of Nanjing Medical University, Nanjing, Jiangsu, China (mainland).

BACKGROUND This United States (U.S.) population study aimed to compare the incidence of neuroblastoma and outcomes in children, adolescents, and adults using the Surveillance, Epidemiology, and End Results (SEER) program database. MATERIAL AND METHODS Patients with neuroblastoma were identified in the SEER database from 1975 to 2013. According to the age at diagnosis, patients were divided into "Children" (≤14 years old) and "Adolescents/Adults" group (>14 years old). Then, comparisons in basic characteristics, incidence rates (IRs) and long-term survival outcomes between patients in 2 groups were made. RESULTS A total of 4280 patients were identified, including 3998 children and 282 adolescent/adult patients. Adolescent/adult patients were more likely to have localized diseases than children and to be diagnosed with ganglioneuroblastoma (all P<0.05). The IR of neuroblastoma presented with upward and downward trends in children and adolescent/adult populations, respectively. Adolescents/adults had worse overall survival (OS) than children despite the earlier tumor stage. Lastly, multivariate Cox proportional hazards analyses showed that tumor stage, histology, sequence of primary malignancy, primary site, the administration of surgery, and treatment era were prognostic factors for children, and sequence of primary malignancy, primary site, undergoing surgery, and treatment era were tightly related to OS in adolescent/adult patients. CONCLUSIONS Analysis of the SEER program database between 1975 to 2013 showed that in the U.S., the incidence of neuroblastoma in children increased, but the incidence decreased in adolescents and adults. There was a trend for improved overall survival in all age groups despite the increased stage at presentation in children.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.12659/MSM.927218DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7711874PMC
November 2020

Intensity non-uniformity correction in MR imaging using residual cycle generative adversarial network.

Phys Med Biol 2020 11 27;65(21):215025. Epub 2020 Nov 27.

Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, GA, 30322, United States of America.

Correcting or reducing the effects of voxel intensity non-uniformity (INU) within a given tissue type is a crucial issue for quantitative magnetic resonance (MR) image analysis in daily clinical practice. Although having no severe impact on visual diagnosis, the INU can highly degrade the performance of automatic quantitative analysis such as segmentation, registration, feature extraction and radiomics. In this study, we present an advanced deep learning based INU correction algorithm called residual cycle generative adversarial network (res-cycle GAN), which integrates the residual block concept into a cycle-consistent GAN (cycle-GAN). In cycle-GAN, an inverse transformation was implemented between the INU uncorrected and corrected magnetic resonance imaging (MRI) images to constrain the model through forcing the calculation of both an INU corrected MRI and a synthetic corrected MRI. A fully convolution neural network integrating residual blocks was applied in the generator of cycle-GAN to enhance end-to-end raw MRI to INU corrected MRI transformation. A cohort of 55 abdominal patients with T1-weighted MR INU images and their corrections with a clinically established and commonly used method, namely, N4ITK were used as a pair to evaluate the proposed res-cycle GAN based INU correction algorithm. Quantitatively comparisons of normalized mean absolute error (NMAE), peak signal-to-noise ratio (PSNR), normalized cross-correlation (NCC) indices, and spatial non-uniformity (SNU) were made among the proposed method and other approaches. Our res-cycle GAN based method achieved an NMAE of 0.011 ± 0.002, a PSNR of 28.0 ± 1.9 dB, an NCC of 0.970 ± 0.017, and a SNU of 0.298 ± 0.085. Our proposed method has significant improvements (p < 0.05) in NMAE, PSNR, NCC and SNU over other algorithms including conventional GAN and U-net. Once the model is well trained, our approach can automatically generate the corrected MR images in a few minutes, eliminating the need for manual setting of parameters.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1088/1361-6560/abb31fDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7934018PMC
November 2020

Enhancing digital tomosynthesis (DTS) for lung radiotherapy guidance using patient-specific deep learning model.

Phys Med Biol 2021 Jan 26;66(3):035009. Epub 2021 Jan 26.

School of Electronic Science and Engineering, Nanjing University, 163 Xianlin Road, Nanjing, Jiangsu, 210046, People's Republic of China. Department of Radiation Oncology, Duke University Medical Center, DUMC Box 3295, Durham, NC 27710, United States of America.

Digital tomosynthesis (DTS) has been proposed as a fast low-dose imaging technique for image-guided radiation therapy (IGRT). However, due to the limited scanning angle, DTS reconstructed by the conventional FDK method suffers from significant distortions and poor plane-to-plane resolutions without full volumetric information, which severely limits its capability for image guidance. Although existing deep learning-based methods showed feasibilities in restoring volumetric information in DTS, they ignored the inter-patient variabilities by training the model using group patients. Consequently, the restored images still suffered from blurred and inaccurate edges. In this study, we presented a DTS enhancement method based on a patient-specific deep learning model to recover the volumetric information in DTS images. The main idea is to use the patient-specific prior knowledge to train the model to learn the patient-specific correlation between DTS and the ground truth volumetric images. To validate the performance of the proposed method, we enrolled both simulated and real on-board projections from lung cancer patient data. Results demonstrated the benefits of the proposed method: (1) qualitatively, DTS enhanced by the proposed method shows CT-like high image quality with accurate and clear edges; (2) quantitatively, the enhanced DTS has low-intensity errors and high structural similarity with respect to the ground truth CT images; (3) in the tumor localization study, compared to the ground truth CT-CBCT registration, the enhanced DTS shows 3D localization errors of ≤0.7 mm and ≤1.6 mm for studies using simulated and real projections, respectively; and (4), the DTS enhancement is nearly real-time. Overall, the proposed method is effective and efficient in enhancing DTS to make it a valuable tool for IGRT applications.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1088/1361-6560/abcde8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7931663PMC
January 2021

Bacterial Outer Membrane Vesicles Presenting Programmed Death 1 for Improved Cancer Immunotherapy Immune Activation and Checkpoint Inhibition.

ACS Nano 2020 Nov 24. Epub 2020 Nov 24.

CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety & CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology of China, 11 Beiyitiao, Zhongguancun, Beijing 100190, China.

Natural, extracellular membrane vesicles secreted by Gram-negative bacteria, outer membrane vesicles (OMVs), contain numerous pathogen-associated molecular patterns which can activate systemic immune responses. Previous studies have shown that OMVs induce strong IFN-γ- and T cell-mediated anti-tumor effects in mice. However, IFN-γ is known to upregulate immunosuppressive factors in the tumor microenvironment, especially the immune checkpoint programmed death 1 ligand 1 (PD-L1), which may hamper T cell function and limit immunotherapeutic effectiveness. Here, we report the development of genetically engineered OMVs whose surface has been modified by insertion of the ectodomain of programmed death 1 (PD1). This genetic modification does not affect the ability of OMVs to trigger immune activation. More importantly, the engineered OMV-PD1 can bind to PD-L1 on the tumor cell surface and facilitate its internalization and reduction, thereby protecting T cells from the PD1/PD-L1 immune inhibitory axis. Through the combined effects of immune activation and checkpoint suppression, the engineered OMVs drive the accumulation of effector T cells in the tumor, which, in turn, leads to a greater impairment of tumor growth, compared with not only native OMVs but also the commonly used PD-L1 antibody. In conclusion, this work demonstrates the potential of bioengineered OMVs as effective immunotherapeutic agents that can comprehensively regulate the tumor immune microenvironment to effect markedly increased anti-tumor efficacy.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acsnano.0c03776DOI Listing
November 2020