Variable Pivot Gait Based a Novel Dynamics Correction Method for Human Lower Limbs Model.

The rationality of gait analysis directly affects the dynamics of human lower limbs in the sagittal plane, and recent studies on gait stage redivision lack the stage when both feet are not in complete contact with the ground. This paper proposes a novel variable pivot gait, which includes the stage when the heel of one foot and the toe of the other are in contact with the ground and a dynamics correction method based on this gait. First, the relative motion data between the foot and the ground are measured by motion capture experiments, and then a variable pivot gait is proposed in terms of the pivot transformation between the foot and the ground. Second, the dynamics modeling is conducted based on the principle of mechanisms of human lower limbs in each stage of the variable pivot gait. Third, a dynamics correction method is proposed to correct the foot dynamics when the foot is not in complete contact with the ground. The experiment and simulation show that the variable pivot gait is consistent with the actual motion of the foot relative to the ground. The effectiveness of the dynamics correction method is proved by comparing dynamics results (hip, knee, and ankle moments) with previous studies. The variable pivot gait and the dynamics correction method can be applied to the human lower limbs and lower-limb robots, providing a new avenue.

Unprecedented phytoplankton blooms in autumn/winter in the southern Bohai Sea (China) due to high Yellow River discharge: Implications of extreme rainfall events.

The occurrence of abnormal phytoplankton blooms is one of the significant changes in coastal ecosystems due to climate change. However, the underlying mechanism of such blooms remains poorly understood due to the complexity of the system. In this study, the data from numerous observations was used to elucidate the unprecedented phytoplankton blooms in the autumn and winter of 2021 in Laizhou Bay, a typical aquaculture bay in the southern Bohai Sea of China. The abundance of phytoplankton cells increased by more than tenfold in the southern waters compared to that in the same period from 2019 to 2020. The phytoplankton bloom was first observed in winter in the Bohai Sea, with the cell abundance in the southern bay exceeding 108 cells L-1 in December 2021. The diversity and evenness of phytoplankton communities decreased in the southern area. Cerataulina pelagica was the dominant algae, comprising 69 % of the total phytoplankton in October and 99 % in December. In autumn 2021, the largest flood of the Yellow River in recent decades occurred. This was attributed to extreme rainfall events within the river basin. The input of substantial riverine nutrients played a significant role in promoting phytoplankton blooms. Correlation analysis indicated the important cumulative impact of the Yellow River on phytoplankton blooms rather than a direct short-term effect. Numerical modeling results indicated that exceptionally high Yellow River discharge in autumn could significantly affect the entire bay from autumn to the following spring. This study may contribute to understanding the abnormal phytoplankton blooms in coastal waters and provide valuable insights for environmental management in river basins and coastal waters.

Optical flow-based closed-loop control of a multi-degree-of-freedom clamping-type ultrasonic motor.

Rotor speed and position detection are integral parts of the closed-loop control system for multi-degree-of-freedom (multi-DOF) ultrasonic motors. The non-contact speed detection method is important for the high-precision control of the spherical rotor. This paper proposes a closed-loop control method based on an optical flow sensor for the velocity-position control of a multi-DOF clamping-type ultrasonic motor. The optical flow information is analyzed using the conical L-K optical flow algorithm to obtain the rotor speed and position. An incremental PID control method is used to perform dual closed-loop positioning control of the motor regarding speed and position. An experimental platform for the optical flow sensor is designed, and the method's feasibility is verified experimentally.

Systematic Study of Heteroarene Stacking Using a Congeneric Set of Molecular Glues for Procaspase-6.

Heteroaromatic stacking interactions are important in drug binding, supramolecular chemistry, and materials science, making protein-ligand model systems of these interactions of considerable interest. Here we studied 30 congeneric ligands that each present a distinct heteroarene for stacking between tyrosine residues at the dimer interface of procaspase-6. Complex X-ray crystal structures of 10 analogs showed that stacking geometries were well conserved, while high-accuracy computations showed that heteroarene stacking energy was well correlated with predicted overall ligand binding energies. Empirically determined KD values in this system thus provide a useful measure of heteroarene stacking with tyrosine. Stacking energies are discussed in the context of torsional strain, the number and positioning of heteroatoms, tautomeric state, and coaxial orientation of heteroarene in the stack. Overall, this study provides an extensive data set of empirical and high-level computed binding energies in a versatile new protein-ligand system amenable to studies of other intermolecular interactions.

Cartilage morphometry and magnetic susceptibility measurement for knee osteoarthritis with automatic cartilage segmentation.

Background: Automatic segmentation of knee cartilage and quantification of cartilage parameters are crucial for the early detection and treatment of knee osteoarthritis (OA). The aim of this study was to develop an automatic cartilage segmentation method for three-dimensional water-selective (3D_WATS) cartilage magnetic resonance imaging (MRI) and conduct cartilage morphometry and magnetic susceptibility measurements such as cartilage thickness, volume, and susceptibility values for knee OA assessment. Methods: Sixty-five consecutively sampled subjects, who had undergone health checks at our hospital, were enrolled in this cross-sectional study and were divided into three groups: 20 normal, 20 mild OA, 25 severe OA. Sagittal 3D_WATS sequence was used to image cartilage at 3T. The raw magnitude images were used for cartilage segmentation and the phase images were used for quantitative susceptibility mapping (QSM)-based assessment. Manual cartilage segmentation was performed by two experienced radiologists, and the automatic segmentation model was constructed using nnU-Net. Quantitative cartilage parameters were extracted from the magnitude and phase images based on the cartilage segmentation. Pearson correlation coefficient and intra-class correlation coefficient (ICC) were then used to assess the consistency of obtained cartilage parameters between automatic and manual segmentation. Cartilage thickness, volume, and susceptibility values among different groups were compared using one-way analysis of variance (ANOVA). Support vector machine (SVM) was used to further verify the classification validity of automatically extracted cartilage parameters. Results: The constructed cartilage segmentation model based on nnU-Net achieved an average Dice score of 0.93. The consistency of cartilage thickness, volume, and susceptibility values calculated using automatic and manual segmentations ranged from 0.98 to 0.99 (95% CI: 0.89-1.00) for the Pearson correlation coefficient, and from 0.91-0.99 (95% CI: 0.86-0.99) for ICC, respectively. Significant differences were found in OA patients; including decreases in cartilage thickness, volume, and mean susceptibility values (P<0.05), and increases in standard deviation (SD) of susceptibility values (P<0.01). Moreover, the automatically extracted cartilage parameters can achieve an AUC value of 0.94 (95% CI: 0.89-0.96) for OA classification using the SVM classifier. Conclusions: The 3D_WATS cartilage MR imaging allows simultaneously automated assessment of cartilage morphometry and magnetic susceptibility for evaluating the severity of OA using the proposed cartilage segmentation method.

A Novel Evaluation Index and Optimization Method for Ankle Rehabilitation Robots Based on Ankle-Foot Motion.

The ability of ankle rehabilitation robots to accurately mimicking the actual human ankle motion is an important judgment basis for robot-assisted rehabilitation training. This paper proposes an evaluation index and mechanism parameter optimization method based on ankle-foot motion trajectory by exploring the human ankle-foot motion principle. First, the ankle UR equivalent model and a 3-degree-of-freedom (DOF) parallel ankle rehabilitation robot are described. Second, the ankle-foot motion data are measured by the body surface marker method, which proved the coupling of ankle-foot motion. Then, a new evaluation index, the ankle-foot motion comfort zone, is proposed, which is essentially the superimposed ankle-foot motion trajectory measured about 3-5 mm wide. Third, a mechanism parameter optimization method, is proposed in terms of the ankle-foot motion comfort zone as the evaluation index, which is applied to the 3-DOF parallel ankle rehabilitation robot, and the optimization results proved the feasibility of the method. Finally, the optimized rehabilitation robot is fitted with different ankle motions, and a prototype model is designed for kinematics simulation, which verifies the adaptability of the optimization method. This study provides a theoretical basis for the configuration design of ankle rehabilitation robots and provides a new direction for the optimization of the mechanism parameters.

Age-Related Changes in the Spatial Variation of Magnetic Susceptibility of Human Articular Cartilage.

BACKGROUND: Quantitative susceptibility mapping (QSM) has shown great potential for revealing the layer structure of articular cartilage based on the laminar susceptibility difference at different depths. However, more information is needed on the effects of age on the spatial distribution of magnetic susceptibility in human cartilage. PURPOSE: To assess the ability of QSM to quantify the age-related differences in depth-wise cartilage susceptibility values in healthy populations. STUDY TYPE: Prospective. POPULATION: A total of 94 healthy asymptomatic subjects in three age cohorts: 19-30 (n = 36, 20 males), 31-50 (n = 45, 27 males), and 51-66 years (n = 13, 7 males). FIELD STRENGTH/SEQUENCE: 3D gradient echo sequences at 3.0 T. ASSESSMENT: Four cartilage compartments were analyzed, including the central lateral/medial femur (cLF/cMF) and the lateral/medial tibia (LT/MT). The spatial susceptibility profile and the corresponding 95% confidence interval (CI) of each age cohort were obtained as functions of the normalized distance from the bone-cartilage interface to the cartilage surface (cartilage depth from 0.0 to 1.0). STATISTICAL TESTS: The relationship between age and cartilage thickness of each cartilage subregion was tested by Pearson correlation with P < 0.05 considered significant. Cartilage depths with separations of 95% CIs were considered to have significant susceptibility differences between two age cohorts with a Bonferroni-corrected P < 0.05. RESULTS: The cartilage thickness did not change significantly with age (P value range: 0.06-0.85). Susceptibilities were significantly higher in the 51-66-year-olds compared with the 31-50-year-olds in the deep layer of cMF (cartilage depth: 0.0-0.22) and LT (0.05-0.28). Susceptibilities were significantly higher in the 51-66-year-olds compared with the 19-30-year-olds near the cartilage-bone interface of cMF (0.0-0.34), cLF (0.0-0.28), and LT (0.0-0.58). There were also significantly higher susceptibilities in the 31-50-year-olds compared with the 19-30-year-olds in the deeper regions of cMF (0.26-0.57), cLF (0.0-0.40), and LT (0.07-0.80). DATA CONCLUSION: Age-related susceptibility changes in the deeper regions of knee cartilage were observed using QSM. EVIDENCE LEVEL: 2 TECHNICAL EFFICACY: Stage 2.

Radiomics analysis using MR imaging of subchondral bone for identification of knee osteoarthritis.

BACKGROUND: To develop a magnetic resonance imaging (MRI)-based radiomics predictive model for the identification of knee osteoarthritis (OA), based on the tibial and femoral subchondral bone, and compare with the trabecular structural parameter-based model. METHODS: Eighty-eight consecutive knees were scanned with 3T MRI and scored using MRI osteoarthritis Knee Scores (MOAKS), in which 56 knees were diagnosed to have OA. The modality of sagittal three-dimensional balanced fast-field echo sequence (3D BFFE) was used to image the subchondral bone. Four trabecular structural parameters (bone volume fraction [BV/TV], trabecular thickness [Tb.Th], trabecular separation [Tb.Sp], and trabecular number) and 93 radiomics features were extracted from four regions of the lateral and medial aspects of the femur condyle and tibial plateau. Least absolute shrinkage and selection operator (LASSO) was used for feature selection. Machine learning-based support vector machine models were constructed to identify knee OA. The performance of the models was assessed by area under the curve (AUC) of the receiver operator characteristic (ROC). The correlation between radiomics features and trabecular structural parameters was analyzed using Pearson's correlation coefficient. RESULTS: Our radiomics-based classification model achieved the AUC score of 0.961 (95% confidence interval [CI], 0.912-1.000) when distinguishing between normal and knee OA, which was higher than that of the trabecular parameter-based model (AUC, 0.873; 95% CI, 0.788-0.957). The first-order, texture, and Laplacian of Gaussian-based radiomics features correlated positively with Tb.Th and BV/TV, but negatively with Tb.Sp (P < 0.05). CONCLUSIONS: Our results suggested that our MRI-based radiomics models can be used as biomarkers for the classification of OA and are superior to the conventional structural parameter-based model.

Development of a 3D-printed pelvic CT phantom combined with fresh pathological tissues of bone tumor.

Background: Computed tomography (CT) imaging is the most important and common means of detecting and diagnosing pelvic bone tumors. While phantoms with sufficient flexibility and anatomical realism are useful in CT research, using phantoms has been difficult for pelvic bone tumors because of the tumors' relatively large size and highly variable shape. By combining medical 3D printing technology and fresh tumor specimens, this study aimed to design such a hybrid phantom, test its imaging properties, and demonstrate its usefulness in optimizing the CT protocols. Methods: Two phantoms were designed for 2 patients with pelvic bone tumors who underwent surgical resection. One phantom was scanned with a routine pelvic CT protocol and compared against the patient image to test the imaging properties. We optimized the imaging protocol by assessing a series of varied settings on tube voltage (80, 100, 120, and 140 kVp), tube current (80, 120, and 160 to 200 mAs), and pitch factor (0.5, 0.8, 1.1, and 1.4) using the other phantom. These were assessed in comparison to the clinical reference of 140 kVp, 240 mAs, and 1.0 pitch, respectively. Image quality was quantified in terms of CT value, image noise, signal to noise ratio (SNR), and contrast to noise ratio (CNR) in various regions of interest. Results: With the routine protocol, the phantom image showed no significant difference in CT values of the bone and soft tissues and image noise compared to the patient image (all P values >0.05). With a lower tube voltage (80, 100, and 120 kVp) than the reference protocol, the CT value of bone tissue showed significant differences (all P values <0.001). No significant difference was found when applying a reduced tube current (all P values >0.05). With an increased helical pitch, pitches of 0.5, 0.8 and 1.1 were found to be comparable to those using the reference protocol (all P values >0.05). Conclusions: The 3D-printed phantom can simulate the radiological properties of tumors in the pelvis and was successfully used in imaging studies of pelvic bone tumors. According to our preliminary findings, a low-dose pelvic CT protocol with acceptable image quality is achievable using reduced tube current or increased pitch.

Using radiomic features of lumbar spine CT images to differentiate osteoporosis from normal bone density.

OBJECTIVE: This study aimed to develop a predictive model to detect osteoporosis using radiomic features from lumbar spine computed tomography (CT) images. METHODS: A total of 133 patients were included in this retrospective study, 41 men and 92 women, with a mean age of 65.45 ± 9.82 years (range: 31-94 years); 53 had normal bone mineral density, 32 osteopenia, and 48 osteoporosis. For each patient, the L1-L4 vertebrae on the CT images were automatically segmented using SenseCare and defined as regions of interest (ROIs). In total, 1,197 radiomic features were extracted from these ROIs using PyRadiomics. The most significant features were selected using logistic regression and Pearson correlation coefficient matrices. Using these features, we constructed three linear classification models based on the random forest (RF), support vector machine (SVM), and K-nearest neighbor (KNN) algorithms, respectively. The training and test sets were repeatedly selected using fivefold cross-validation. The model performance was evaluated using the area under the receiver operator characteristic curve (AUC) and confusion matrix. RESULTS: The classification model based on RF had the highest performance, with an AUC of 0.994 (95% confidence interval [CI]: 0.979-1.00) for differentiating normal BMD and osteoporosis, 0.866 (95% CI: 0.779-0.954) for osteopenia versus osteoporosis, and 0.940 (95% CI: 0.891-0.989) for normal BMD versus osteopenia. CONCLUSIONS: The excellent performance of this radiomic model indicates that lumbar spine CT images can effectively be used to identify osteoporosis and as a tool for opportunistic osteoporosis screening.

A multi-degree-of-freedom clamping type traveling-wave ultrasonic motor.

This paper proposes a multi-degree-of-freedom (multi-DOF) ultrasonic motor with four stators clamping a spherical rotor. The stator surface teeth are inclined at a certain angle, using the inclined surface to contact the rotor and transfer energy. The motor frame is exquisitely designed in which substrates hold four identical stators to drive the rotor to achieve a multi-DOF rotation. COMSOL Multiphysics performs the stator's modal analysis and harmonic response analysis to illustrate the vibration mode and frequency response. A prototype is fabricated to verify the operating principle and conduct the performance tests. The experimental results indicate that the motor can reach a no-load speed of 100r/min, and the stalling torque is 150mNm under a preload of 113 N. The results also denote the motor has a high load-carrying capacity with a maximum load torque of 143mNm and accurate operation with a maximum error of 0.15 mm.

Measurement and modeling of hormesis in soil bacteria and fungi under single and combined treatments of Cd and Pb.

Heavy metals are considered major environmental pollutants. Soil microorganisms represent a predominant component of soils ecosystems, yet there is little information regarding hormetic responses of soil microorganisms to single and combined exposures to heavy metals. In the present study, to explore and predict the hormetic response of soil microorganisms, dose-response relationships of bacterial and fungal populations to single and combined treatments of cadmium (Cd) and lead (Pb) were evaluated. The results revealed hormetic responses of bacterial and fungal populations to both single and combined Cd and Pb treatments. The maximum stimulation (Mmax; relative to control treatment with no metals) of bacterial and fungal populations was 40% at 2 mg Cd/kg and 60% at 160 mg Pb/kg. An enhanced Mmax occurred in bacterial (50%) and fungal (75%) populations in the presence of the binary mixtures of 0.6 mg Cd/kg + 160 mg Pb/kg and 4.0 mg Cd/kg + 200 mg Pb/kg, suggesting positive additivity. This study showed that the hormetic effects of the mixtures were related to the independent effect of Cd and Pb, but they could not be predicted by the single effect of Cd or Pb. These new findings of the hormetic response of soil microorganisms to single treatments of Cd and Pb and their binary mixtures can facilitate the determination and minimization of ecological risks in heavy metal-polluted soils.

[Kinematics analysis and scale optimization of four degree of freedom generalized spherical parallel mechanism for ankle joint rehabilitation].

By analyzing the physiological structure and motion characteristics of human ankle joint, a four degree of freedom generalized spherical parallel mechanism is proposed to meet the needs of ankle rehabilitation. Using the spiral theory to analyze the motion characteristics of the mechanism and based on the method of describing the position with spherical coordinates and the posture with Euler Angle, the inverse solution of the closed vector equation of mechanism position is established. The workspace of mechanism is analyzed according to the constraint conditions of inverse solution. The workspace of the moving spherical center of the mechanism is used to match the movement space of the tibiotalar joint, and the workspace of the dynamic platform is used to match the movement space of subtalar joint. Genetic algorithm is used to optimize the key scale parameters of the mechanism. The results show that the workspace of the generalized spherical parallel mechanism can satisfy the actual movement space of human ankle joint rehabilitation. The results of this paper can provide theoretical basis and experimental reference for the design of ankle joint rehabilitation robot with high matching degree.

Diffusion Kurtosis Imaging as a Prognostic Marker in Osteosarcoma Patients with Preoperative Chemotherapy.

BACKGROUND: The accurate prediction of prognosis is key to prompt therapy adjustment. The purpose of our study was to investigate the efficacy of diffusion kurtosis imaging (DKI) in predicting progression-free survival (PFS) and overall survival (OS) in osteosarcoma patients with preoperative chemotherapy. METHODS: Thirty patients who underwent DKI before and after chemotherapy, followed by tumor resection, were retrospectively enrolled. The patients were grouped into good responders (GRs) and poor responders (PRs). The Kaplan-Meier and log-rank test were used for survival analysis. The association between the DKI parameters and OS and PFS was performed by univariate and multivariate Cox proportional hazards models. RESULTS: Significantly worse OS and PFS were associated with a lower mean diffusivity (MD) after chemotherapy (HR, 5.8; 95% CI, 1.5-23.1; P = 0.012 and HR, 3.5; 95% CI, 1.2-10.1: P = 0.028, respectively) and a higher mean kurtosis (MK) after chemotherapy (HR, 0.3; 95% CI, 0.1-0.9; P = 0.041 and HR, 0.3; 95% CI, 0.1-0.8; P = 0.049, respectively). Likewise, shorter OS and PFS were also significantly associated with a change rate in MD (CR MD) of less than 13.53% (HR, 8.6; 95% CI, 1.8-41.8; P = 0.007 and HR, 2.9; 95% CI, 1.0-8.2; P = 0.045, respectively). Compared to GRs, PRs had an approximately 9- and 4-fold increased risk of death (HR, 9.4; 95% CI, 1.2-75; P = 0.034) and progression (HR, 4.2; 95% CI, 1.2-15; P = 0.026), respectively. CONCLUSIONS: DKI has a potential to be a prognostic tool in osteosarcoma. Low MK and high MD after chemotherapy or high CR MD indicates favorite outcome, while prospective studies with large sample sizes are warranted.

Association of Preoperative Neutrophil/Lymphocyte Ratio with Clinical Outcomes in Dedifferentiated Chondrosarcoma Patients.

BACKGROUND: Dedifferentiated chondrosarcoma (DC) is an extremely uncommon malignant bone tumor with dismal survival outcomes. The purpose of this study was to investigate whether the preoperative neutrophil/lymphocyte ratio (NLR) has the ability to predict overall survival (OS) in DC patients. MATERIALS AND METHODS: Twenty-three DC patients with surgical resection were retrospectively reviewed between 2008 and 2015. The clinical pathological information and survival data were collected for analysis. The cut-off point for NLR was defined by receiver operating curve (ROC). The impact of NLR level on OS between two groups was compared using Kaplan-Meier curves with the Log-rank test. The association between NLR and OS was calculated by univariate and multivariate Cox proportional models. RESULTS: From the ROC analysis, the optimal NLR cut-off point was 3.11. Patients with high NLR had a worse OS than low NLR (p = 0.003, Log-rank test). In univariate analysis, a significant association was observed between high NLR and poor OS (Hazard ratio (HR) 4.62, 95% confidence interval (CI) 1.48-14.34, p = 0.008). After adjustment of co-variables, high NLR had more than 4 times the risk of mortality (HR 4.01, 95% CI 1.12-14.26, p = 0.032). CONCLUSION: Preoperative NLR in peripheral blood is an easily accessible and cost-effective prognostic biomarker in DC patients. A prospective study with large sample size is warranted.

Upregulation of secreted phosphoprotein 1 affects malignant progression, prognosis, and resistance to cetuximab via the KRAS/MEK pathway in head and neck cancer.

Acquired resistance is a barrier to cetuximab efficacy in patients with head and neck squamous cell carcinoma (HNSCC). Secreted phosphoprotein 1 (SPP1) is involved in various biological processes, including immune responses, cancer progression, and prognosis in many cancers, while little is known in HNSCC. Bioinformatics methods were used to identify candidate genes and further in vivo and in vitro experiments were performed to examine and validate the function of SPP1. We found that SPP1 was upregulated and has been found to have an oncogenic role in HNSCC. We further confirmed that overexpression of SPP1 affected proliferation, migration, invasion, and survival, and inhibited apoptosis, whereas silencing of SPP1 yielded opposite results to those of SPP1 overexpression. In addition, activation of the KRAS/MEK pathway contributed to the SPP1-induced malignant progression of HNSCC and resistance to cetuximab. Furthermore, SPP1 knockdown or an MEK inhibitor overcame this cetuximab-resistance pattern. Taken together, our findings for the first time identify the role of SPP1 in tumor promotion, prognostic prediction, and potential therapeutic targeting, as well as resistance to cetuximab in HNSCC.

Magnitude of the mixture hormetic response of soil alkaline phosphatase can be predicted based on single conditions of Cd and Pb.

In soil ecosystems, it is very challenging to predict mixture hormesis effects. In the present study, soil alkaline phosphatase (ALP) was selected to investigate and predict its potential hormetic responses under Cd and Pb stresses. Typical reverse U-shaped dose-response relationships between ALP activities and the single and combined Cd and Pb were observed, showing a hormetic response of soil itself. The maximum stimulatory magnitudes ranged in 8.0 - 8.6% under 0.004 - 0.2 mg/kg Cd and 80 - 400 mg/kg Pb, respectively. An enhanced stimulation of 15.7% occurred under the binary mixtures of 0.6 mg/kg Cd and 200 mg/kg Pb. In addition, a dosage-independent binary linear regression model was proposed based on an assumption of a linear relationship between the single and combined hormetic responses under Cd and Pb. Our model can well predict ALP's responses in the presence of the two metals' mixtures (p < 0.1). Our findings provided new understandings to hormesis in soil.

Time-Dependent Hormetic Response of Soil Alkaline Phosphatase Induced by Cd and the Association with Bacterial Community Composition.

Hormetic dose-response that involved Cd in soils is increasingly paid attentions for risk assessment of Cd toxicity, but insufficient studies were conducted to define the temporary modification of soil enzyme and the potential microbial responses. The present study chooses soil alkaline phosphatase (ALP) as endpoint to uncover the time-dependent hormetic responses to low doses of Cd and its association with bacterial community composition. The results showed that addition of 0.01-3.0 mg kg-1 Cd significantly increased ALP's activities with maximum stimulatory magnitude of 11.4-27.2%, indicating a typical hormesis. The response started at 12 h after Cd addition and maintained about 24 h. This demonstrated that the hormetic response is time-dependent and transient. Changes of soil bacterial community composition showed that, at 6 h, relative abundances (RAs) of Proteobacteria and Firmicutes at phylum and Pontibacter, Bacillaceae-Bacillus, Bacillaceae1-Bacillus, and Paenisporosarcina at genus significantly correlated with ALP's activities at 12-36 h (P < 0.05). This suggests that soil bacteria likely showed an earlier response to Cd and potentially contributes to the subsequent soil enzyme's hormesis. In addition, it was found that Gram-negative bacteria other than Gram-positive bacteria are prone to exhibiting a hormetic response under Cd stress. Our findings provide much insight into ecotoxicological risk assessment for soil Cd pollution.

Monitoring Response to Neoadjuvant Chemotherapy of Primary Osteosarcoma Using Diffusion Kurtosis Magnetic Resonance Imaging: Initial Findings.

OBJECTIVE: To determine whether diffusion kurtosis imaging (DKI) is effective in monitoring tumor response to neoadjuvant chemotherapy in patients with osteosarcoma. MATERIALS AND METHODS: Twenty-nine osteosarcoma patients (20 men and 9 women; mean age, 17.6 ± 7.8 years) who had undergone magnetic resonance imaging (MRI) and DKI before and after neoadjuvant chemotherapy were included. Tumor volume, apparent diffusion coefficient (ADC), mean diffusivity (MD), mean kurtosis (MK), and change ratio (ΔX) between pre- and post-treatment were calculated. Based on histologic response, the patients were divided into those with good response (≥ 90% necrosis, n = 12) and those with poor response (< 90% necrosis, n = 17). Several MRI parameters between the groups were compared using Student's t test. The correlation between image indexes and tumor necrosis was determined using Pearson's correlation, and diagnostic performance was compared using receiver operating characteristic curves. RESULTS: In good responders, MDpost, ADCpost, and MKpost values were significantly higher than in poor responders (p < 0.001, p < 0.001, and p = 0.042, respectively). The ΔMD and ΔADC were also significantly higher in good responders than in poor responders (p < 0.001 and p = 0.01, respectively). However, no significant difference was observed in ΔMK (p = 0.092). MDpost and ΔMD showed high correlations with tumor necrosis rate (r = 0.669 and r = 0.622, respectively), and MDpost had higher diagnostic performance than ADCpost (p = 0.037) and MKpost (p = 0.011). Similarly, ΔMD also showed higher diagnostic performance than ΔADC (p = 0.033) and ΔMK (p = 0.037). CONCLUSION: MD is a promising biomarker for monitoring tumor response to preoperative chemotherapy in patients with osteosarcoma.

Relationship between subchondral bone microstructure and articular cartilage in the osteoarthritic knee using 3T MRI.

BACKGROUND: The importance of subchondral bone in the pathogenesis of osteoarthritis (OA) has drawn interest. PURPOSE: To investigate subregional trabecular bone microstructural features and to determine the relationship between cartilage and trabecular bone in the osteoarthritic human knee. STUDY TYPE: Prospective study. SUBJECTS: In all, 92 knees were enrolled and divided into three groups: without OA, mild OA, and severe OA. SEQUENCE: A sagittal 3D balanced fast field echo (3D B-FFE) sequence and FatSat 3D fast field echo (3D-FFE) sequence at 3T MRI. ASSESSMENT: The trabecular bone in 12 sites of the knee joint was evaluated using digital topological analysis, and the cartilage thickness in four sites was calculated. STATISTICAL TEST: Trabecular bone and cartilage parameters between groups were compared using analysis of variance (ANOVA) with Bonferroni adjustment, and their correlations were analyzed using Pearson's correlation coefficient. RESULTS: Within both femoral condyles, the trabecular bone structure deteriorated in mild OA, showing a lower bone volume fraction (BVF) (0.15 to 0.12, P < 0.05), higher erosion index (EI) (2.25 to 2.28, P < 0.01), and a lower plate-to-rod ratio (SCR) (6.22 to 5.96, P < 0.05). Within medial and lateral tibia, deterioration in the trabecular bone was also observed, demonstrating a lower BVF (0.15 to 0.12 P < 0.05) and a higher EI (2.25 to 2.61, P < 0.05). Cartilage attrition mainly occurred in the medial joint. Extensive correlations were found between the medial cartilage thickness and subregional trabecular parameters. There was mainly a positive correlation with both femoral BVFs (r > 0.3, P < 0.05), and a negative correlation with the tibia SCR (r < -0.2, P < 0.05). DATA CONCLUSION: In the early stage of OA, trabecular bone osteoporotic changes were observed in both femoral condyles and the tibia. Based on a strong correlation with the medial cartilage thickness, the trabecular structural topological analysis may be useful for elucidating OA onset and progression. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018.