[Distribution Prediction of Soil Heavy Metals Based on Remote Sensing Temporal-Spatial-Spectral Features and Random Forest Model].

Obtaining soil heavy metal content characteristics and spatial distribution is crucial for preventing soil pollution and formulating environmental protection policies. We collected 304 surface soil samples (0-20 cm) in the Changqing district. At the same time, the spectral, temporal, and spatial features of soil heavy metals were derived from multi-remote sensing data; the temporal-spatial-spectral features closely related to soil heavy metals were selected via correlation analysis and used as input independent variables. The measured soil arsenic (As) content was used as the dependent variable to establish a spatial prediction model based on the random forest (RF) algorithm. The results showed the following:the As content in the soils exceeded the background value by 43.17% but did not exceed the risk screening values and intervention values, indicating slight heavy metal pollution in the soil. The accuracy ranking of the spatial prediction models with one feature type from high to low was spatial features (ratio of performance to inter-quartile range (RPIQ)=3.87)>temporal features (RPIQ=2.57)>spectral features (RPIQ=2.50). The spatial features were the most informative for predicting soil heavy metals. The models using temporal-spatial, temporal-spectral, and spatial-spectral features were superior to those using only one feature type, and the RPIQ values were 4.81, 4.21, and 4.70, respectively. The RF model with temporal-spatial-spectral features achieved the highest spatial prediction accuracy (R2=0.90; root mean square error (RMSE)=0.77; RPIQ=5.68). The As content decreased from the northwest to the southeast due to Yellow River erosion and industrial activities. The spatial prediction of soil heavy metals incorporating remote sensing temporal-spatial-spectral features and the random forest model provides effective support for soil pollution prevention and environmental risk control.

Ultrasensitive electrochemical platform for the p53 gene via molecular beacon-mediated circular strand displacement and terminal deoxynucleotidyl transferase-mediated signal amplification strategy.

As an important tumor suppressor gene, the p53 gene is considered to be a typical biomarker for the early diagnosis and prognosis evaluation of severe cancer. Herein, an electrochemical biosensor was proposed for the ultrasensitive detection of the p53 gene based on molecular beacon-mediated circular strand displacement polymerization combined with terminal deoxynucleotide transferase-mediated template-free DNA extension. Firstly, the p53 gene opened the hairpin structure of the molecular beacon, thereby exposing the binding sequence region of the primer DNA. The circular strand displacement polymerization occurred in the presence of the primer DNA and phi29 DNA polymerase, subsequently resulting in the circulation of the p53 gene. With the catalysis of the terminal deoxynucleotide transferase, the 3'-OH terminal sequence of the molecular beacon elongated to produce long single-stranded DNA under the template-free DNA extension. Methylene blue bound with such DNA strands generated a strong differential pulse voltammetry (DPV) signal with a peak potential of -0.28 V. Under the optimal detection conditions, the DPV signal of methylene blue showed good linear relationships with the logarithm value of the p53 gene in two concentration ranges of 0.05 fM to 3 pM and 5 fM to 100 fM, and the detection limit of the p53 gene was as low as 0.018 fM. This electrochemical biosensor possessed high recognition ability for the p53 gene in its analogues and was successfully applied for p53 gene analysis in human serum samples.

A label-free and ultrasensitive electrochemical biosensor for oral cancer overexpressed 1 gene via exonuclease III-assisted target recycling and dual enzyme-assisted signal amplification strategies.

A label-free and ultrasensitive electrochemical biosensor for oral cancer overexpressed 1 (ORAOV1) gene was constructed via exonuclease III-assisted target recycling and dual enzyme-assisted signal amplification strategies. Capture DNA with a sulfhydryl group at its 3' terminus was modified onto the surface of a bare gold electrode via an Au-S bond. Assisted DNA hybridized with basal DNA to form hybrid DNA in advance, and ORAOV1 gene hybridized continuously with such a hybrid DNA from the other terminus to construct intact double-stranded DNA. Exonuclease III digested basal DNA in such intact double-stranded DNA specifically, and both ORAOV1 gene and assisted DNA were released into solution. ORAOV1 gene induced another intact double-stranded DNA digestion for target recycling, while assisted DNA hybridized with the capture DNA to form double-stranded DNA on the modified electrode surface. Unhybridized capture DNA on the modified electrode surface was hydrolyzed by RecJf exonuclease to reduce the background electrochemical signal. The 3' terminus of double-stranded DNA on the modified electrode surface was prolongated to be guanine-rich oligonucleotides under the catalysis of terminal deoxynucleotidyl transferase. In the presence of K+ ions, hemin adsorbed onto guanine-rich oligonucleotides to construct a G-quadruplex/hemin complex with a large steric hindrance effect to efficiently avoid the charge transfer of the [Fe(CN)6]3-/4- probe toward the electrode surface. The electrochemical impedance value was increased significantly after the addition of ORAOV1 gene via exonuclease III-assisted target recycling and dual enzyme-assisted signal amplification strategies. The electrochemical impedance value was linearly related to the logarithmic concentration of ORAOV1 gene in the range from 0.05 fM to 20 pM, and the detection limit of ORAOV1 gene was low to 0.019 fM. This biosensor was used to detect ORAOV1 gene in complicated human saliva samples with satisfactory results.

[Responses of radial growth of Pinus sylvestris var. mongolica and Larix gmelinii to climate change]. / 樟子松和落叶松径向生长对气候变化的响应.

In the context of global warming, the increases of temperature may affect tree growth and thus disturb ecosystem balance. In this study, we explored the main limiting factors for radial growth of Pinus sylvestris var. mongolica and Larix gmelinii in the Mohe area of Greater Khingan Mountains by using growth-climate response function analysis and moving correlation analysis, as well as the interspecific difference of the responses of radial growth to rapid warming. The results showed that the radial growth of P. sylvestris var. mongolica and L. gmelinii was affected by both temperature and precipitation. P. sylvestris var. mongolica was more sensitive to climate change than L. gmelinii, and its sensitivity to climate factors was more stable than L. gmelinii. The radial growth of P. sylvestris var. mongolica was significantly positively correlated with the monthly mean temperature and the monthly mean minimum temperature of the growing season, while that of L. gmelinii was significantly positively correlated with the monthly mean temperature and the monthly mean maximum temperature of winter. Precipitation in winter promoted the growth of P. sylvestris var. mongolica, whereas precipitation in the late growing season of the previous year inhibited the radial growth of L. gmelinii. After the rapid warming in 1990, the limiting effect of precipitation on P. sylvestris var. mongolica changed from negative to significantly positive, with the inhibition effect of high temperature being greater than the promotion effect. The inhibitory effect of high temperature on L. gmelinii was enhanced, and the limiting effect of precipitation on L. gmelinii was also enhanced after heating up. The growth rate decreased significantly, with obvious difference being observed in the correlations between the growth rate of two species with temperature and precipitation. Our results could provide scientific basis for forest ecosystem management and protection in Greater Khingan Mountains.

How to evaluate the value of chest CT in COVID-19: case reports and literature review.

The coronavirus disease 2019 (COVID-19) that occurred in Wuhan, Hubei Province, China, has been declared a public health emergency of international concern and a pandemic by the World Health Organization. The Chinese government has temporarily taken strong response measures and effective procedures to stop the further expansion and development of the epidemic. It is important for clinicians to screen, diagnose, and monitor COVID-19.

Three dimensional texture analysis of noncontrast chest CT in differentiating solitary solid lung squamous cell carcinoma from adenocarcinoma and correlation to immunohistochemical markers.

BACKGROUND: The aim of the study was to investigate 3D texture analysis (3D-TA) in noncontrast enhanced computed tomography (CT) (NCECT) to differentiate squamous cell carcinoma (SCC) from adenocarcinoma (AC), and the correlation with immunohistochemical markers. METHODS: A total of 70 patients confirmed with SCC (n = 29) and AC (n = 41) were enrolled in this retrospective study. 3D-TA was utilized to calculate TA parameters of all the tumor lesions based on NCECT images, and all the patients were divided into the training and the test groups. The TA parameters were selected by dimensionality reduction, and the model was established to differentiate SCC from AC according to the training group. The ROC curve was used to evaluate the diagnostic efficiency of the model in both the training and the test groups. Spearman correlation were used to assess the correlation between the selected feature parameters and immunohistochemical markers (P63, P40, and TTF-1). RESULTS: Five TA parameters, including volume count, relative deviation, Haralick correlation, gray-level nonuniformity and run length nonuniformity, were obtained to differentiate SCC from AC by multistep dimensionality reduction. The new model combined with all five TA parameters yielded a high diagnostic performance to differentiate SCC from AC (AUC 0.803) in test group, with a specificity of 89% and a sensitivity of 77%. There was weak correlation between the five texture feature parameters and P63 as well as P40 in all patients (P < 0.05), respectively. CONCLUSIONS: The model including five TA parameters on NECT has a good diagnostic performance in differentiating SCC from AC. KEY POINTS: • Significant findings of the study The model created by five selected textural feature parameters can differentiate solid SCC from AC without contrast media. The selected five texture feature parameters are correlated to the immunohistochemical markers P63 and P40. • What this study adds The textural feature parameters' model can identify SCC from AC without contrast media.

The value of serum amyloid A for predicting the severity and recovery of COVID-19.

The present study aimed to evaluate the value of serum amyloid A (SAA) in coronavirus disease 2019 (COVID-19) and compared the efficacy of SAA and C-reactive protein (CRP) in predicting the severity and recovery of COVID-19. A retrospective study was conducted on COVID-19 patients hospitalized in Wuhan No. 1 Hospital (Hubei, China) from January 21, 2020 to March 4, 2020. A two-way ANOVA analysis was used to compare the serum CRP and SAA levels between mild group and severe group during hospitalization days. Linear regression was used to analyze the relationship between the serum CRP, SAA levels and treatment days in recovered patients. The Logistic regression analysis and the area under curve (AUC) were calculated to determine the probability for predicting the severity and recovery of COVID-19. The severe group displayed higher CRP and SAA levels compared with the mild group during hospitalization (P<0.001). Logistic regression indicated that SAA and CRP were independent risk factors for the severity of COVID-19. The corresponding AUC of CRP and SAA values for severity of COVID-19 were 0.804 and 0.818, respectively. Linear regression analysis revealed that CRP and SAA levels were negatively correlated with treatment days in recovered patients (r=-0.761, -0.795, respectively). Logistic regression demonstrated that SAA was an independent factor for predicting the recovery of COVID-19. However, CRP could not predict the recovery of COVID-19. The corresponding AUC of SAA for the recovery of COVID-19 was 0.923. The results of the present study indicated that SAA can be considered to be a biomarker for predicting the severity and recovery of COVID-19.

Factors controlling the spatial distribution of soil organic carbon in Daxing'anling Mountain.

Daxing'anling Mountain, in the northeastern part of China, contains a large amount of soil organic carbon (SOC). Using data including topography, climate, and vegetation, the spatial distribution of SOC content was modeled using classical and geography-based statistics, as well as a geographically weighted kriging model. The study findings include: (1) SOC content generally ranges 40-70 g/kg, with high SOC content in the southwest and low SOC content in the southeast; (2) Results of principal component analysis suggested the normalized difference vegetation index is the best predictor of patterns in SOC; and (3) The geo-weighted regression Kriging model well reflects factors influencing spatial distribution of SOC content. This study provides important baseline information for environmental protection in the Daxing'anling Mountain area, as well as general information as to important factors that mediate this important reservoir of soil carbon.

Early Clinical and CT Manifestations of Coronavirus Disease 2019 (COVID-19) Pneumonia.

OBJECTIVE. The purpose of this study was to investigate early clinical and CT manifestations of coronavirus disease (COVID-19) pneumonia. MATERIALS AND METHODS. Patients with COVID-19 pneumonia confirmed by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleic acid test (reverse transcription-polymerase chain reaction) were enrolled in this retrospective study. The clinical manifestations, laboratory results, and CT findings were evaluated. RESULTS. One hundred eight patients (38 men, 70 women; age range, 21-90 years) were included in the study. The clinical manifestations were fever in 94 of 108 (87%) patients, dry cough in 65 (60%), and fatigue in 42 (39%). The laboratory results were normal WBC count in 97 (90%) patients and normal or reduced lymphocyte count in 65 (60%). High-sensitivity C-reactive protein level was elevated in 107 (99%) patients. The distribution of involved lobes was one lobe in 38 (35%) patients, two or three lobes in 24 (22%), and four or five lobes in 46 (43%). The major involvement was peripheral (97 patients [90%]), and the common lesion shape was patchy (93 patients [86%]). Sixty-five (60%) patients had ground-glass opacity (GGO), and 44 (41%) had GGO with consolidation. The size of lesions varied from smaller than 1 cm (10 patients [9%]) to larger than 3 cm (56 patients [52%]). Vascular thickening (86 patients [80%]), crazy paving pattern (43 patients [40%]), air bronchogram sign (52 patients [48%]), and halo sign (69 [64%]) were also observed in this study. CONCLUSION. The early clinical and laboratory findings of COVID-19 pneumonia are low to midgrade fever, dry cough, and fatigue with normal WBC count, reduced lymphocyte count, and elevated high-sensitivity C-reactive protein level. The early CT findings are patchy GGO with or without consolidation involving multiple lobes, mainly in the peripheral zone, accompanied by halo sign, vascular thickening, crazy paving pattern, or air bronchogram sign.

Electroacupuncture stimulates remodeling of extracellular matrix by inhibiting apoptosis in a rabbit model of disc degeneration.

The present study was designed to determine whether EA stimulates remodeling of extracellular matrix by inhibiting apoptosis in degenerated disc. 40 rabbits were randomly assigned to one of the four groups. Animal model was established by a loading device. Magnetic resonance imaging and Pfirrmann's classification were obtained to evaluate both the model and the EA treatment on disc degeneration. The ultrastructure of discs was observed by TEM. Apoptosis involvement was determined with TUNEL staining and western blot for the protein expression of Bax and Bcl-2. The results indicated that EA intervention decreased the MRI grades. TEM analysis showed an apparent remodeling and rearrangement of disc ECM after EA intervention for 28 days. The number of TUNEL-positive cells in the EA group was significantly lower than that in the compression group. The protein expression demonstrated an antiapoptosis effect mediated by EA. Increased expression of Bcl-2 proteins and reduced Bax protein expression were detected after 28 days treatment. It was concluded that antiapoptosis pathway probably participates in the mechanism of EA stimulating the remodeling of ECM in disc degeneration.

Assessment of apparent diffusion coefficient of normal fetal brain development from gestational age week 24 up to term age: a preliminary study.

OBJECTIVES: This study was designed to investigate the feasibility of apparent diffusion coefficient (ADC) values in evaluating normal fetal brain development from gestational week 24 up to term age. METHODS: Diffusion-weighted imaging (DWI) was performed on 40 normal fetuses (with normal results on sonography and normal fetal MRI results), with two b-values of 0 and 600 s/mm² in the three (x, y, z) orthogonal axes. Ten regions of interest (ROIs) were manually placed symmetrically in the bilateral frontal white matter (FWM), occipital white matter (OWM), thalamus (THAL), basal ganglia (BG), and cerebellar hemispheres (CH). ADC values of the ten ROIs in all subjects were measured by two radiologists independently. One-way ANOVA was used to calculate the differences among the five regions in the fetal brain and linear regression analysis was used to evaluate the correlation between ADC values and gestational age (GA). p < 0.05 was considered significantly different. RESULTS: Mean GA was 31.3 ± 3.9 (range 24-41) weeks. The overall mean ADC values (× 10⁻6 mm²/s) of the fetuses were 1,800 ± 214 (FWM), 1,400 ± 100 (BG), 1,300 ± 126 (THAL), 1,700 ± 133 (OWM) and 1,400 ± 155 (CH), respectively. The ADC value of BG was not significantly different from those of THAL and CH, while the other four ROIs had significant differences with each other. The ADC values of BG, THAL, OWM and CH had strong negative correlations with increasing GA (R were -0.568, -0.716, -0.830 and -0.700, respectively, all p < 0.01), OWM declined fastest with GA, followed by CH and THAL, the slowest being BG. The ADC value of FWM had no significant change with GA (p = 0.366). CONCLUSIONS: The measurement of ADC values is feasible to evaluate fetal brain development with high reliability and reproducibility.

The effect of electroacupuncture on the extracellular matrix synthesis and degradation in a rabbit model of disc degeneration.

The present study was aimed at determining if the electroacupuncture (EA) is able to protect degenerated disc in vivo. New Zealand white rabbits (n = 40) were used for the study. The rabbits were randomly assigned to four groups. EA intervention was applied to one of the four groups. Magnetic resonance imaging and Pfirrmann's classification were obtained for each group to evaluate EA treatment on the intervertebral disc degeneration. Discs were analyzed using immunofluorescence for the labeling of collagens 1 and 2, bone morphogenetic protein-2 (BMP-2), matrix metalloproteinase-13 (MMP-13), and tissue inhibitor of matrix metalloproteinase-1 (TIMP-1). For protein expression analysis, western blot was used for biglycan and decorin. Outcomes indicated that EA intervention decreased the grades compared with the compressed disc. Immunofluorescence analysis showed a significant increase of collagens 1 and 2, TIMP-1, and BMP-2 positive cells, in contrast to MMP-13 after EA treatment for 28 days. The protein expression showed a sign of regeneration that decorin and biglycan were upregulated. It was concluded that EA contributed to the extracellular matrix (ECM) anabolic processes and increased the ECM components. MMPs and their inhibitors involved in the mechanism of EA intervention on ECM decreased disc. It kept a dynamic balance between ECM synthesis and degradation.

[Magnetic resonance imaging character in chronic injury of the elbows in athletes].

OBJECTIVE: To introduce the experiences of applying MR to diagnose the imaging characters in chronic injury of the elbows in athletes. METHODS: From September 2005 to May 2008, 40 elbows of 34 athletes, included 21 males and 13 females,aged from 6 to 16 years old, averaged (12.3 +/- 3.1) years were taken axial, saggital and coronal planes MR Imaging. RESULTS: Magnetic resonance imaging showed thickening and effusion of olecranon synovial plicaes, bone marrow edema of lower humeral ossification, radial head, olecranon, ulna coronoid, ulnar collateral ligament trauma in chronic injury of the elbow joint. CONCLUSION: MRI is a susceptible method for the diagnoses of chronic injury of the elbow.