Enhance the Accuracy of Landslide Detection in UAV Images Using an Improved Mask R-CNN Model: A Case Study of Sanming, China.

Extracting high-accuracy landslide areas using deep learning methods from high spatial resolution remote sensing images is a hot topic in current research. However, the existing deep learning algorithms are affected by background noise and landslide scale effects during the extraction process, leading to poor feature extraction effects. To address this issue, this paper proposes an improved mask regions-based convolutional neural network (Mask R-CNN) model to identify the landslide distribution in unmanned aerial vehicles (UAV) images. The improvement of the model mainly includes three aspects: (1) an attention mechanism of the convolutional block attention module (CBAM) is added to the backbone residual neural network (ResNet). (2) A bottom-up channel is added to the feature pyramidal network (FPN) module. (3) The region proposal network (RPN) is replaced by guided anchoring (GA-RPN). Sanming City, China was selected as the study area for the experiments. The experimental results show that the improved model has a recall of 91.4% and an accuracy of 92.6%, which is 12.9% and 10.9% higher than the original Mask R-CNN model, respectively, indicating that the improved model is more effective in landslide extraction.

Hypertension related toxicity of chloroquine explains its failure against COVID-19: Based on rat model.

Chloroquine was once thought to be a promising treatment for COVID-19 but it quickly failed due to its inefficiency and association with increased mortality. Further, comorbidities such as hypertension may have contributed this failure. The safety and toxicity of chloroquine at doses required for treating SARS-CoV-2 infection in hypertensive patients remain unknown. Herein, to investigate these effects, we performed a safety evaluation of chloroquine at the approved dose (63 mg/kg) and at a high dose (126 mg/kg) in hypertensive rats. We found that chloroquine increased the mortality of hypertensive rats to 18.2% and 100%, respectively, after 7 days. During the chloroquine exposure period, the bodyweight, feed, and water consumption of hypertensive rats were decreased significantly. In addition, we show that chloroquine induces prolongation of QTc interval, elevation of LDH and CK, and histopathological damage of the myocardium in hypertensive rats. Ocular toxicity was observed in hypertensive rats in the form of hemorrhage in the eyes and retinal damage. Furthermore, we also observed intestinal toxicity in hypertensive rats, which presented as thinning intestinal walls with hemorrhagic contents, and histopathological changes of the jejunum. Hepatotoxicity was also evidenced by elevated ALT, and vacuolization of hepatocytes was also observed. Nephrotoxicity was observed only in high dose chloroquine-treated hypertensive rats, presenting as alterations of urinalysis and renal function. Immune alterations were also found in high-dose chloroquine-treated hypertensive rats with elevation of serum IL-10, IL-1ß and GRO, and moderate damage to the spleen. In summary, this study partially explains the reason for the failure of chloroquine as a COVID-19 therapy, and underlines the importance of safety evaluation and medical supervision of chloroquine to avoid patient harm, especially to those with hypertension.

Genotyping and biofilm formation of Mycoplasma hyopneumoniae and their association with virulence.

Mycoplasma hyopneumoniae, the causative agent of swine respiratory disease, demonstrates differences in virulence. However, factors associated with this variation remain unknown. We herein evaluated the association between differences in virulence and genotypes as well as phenotype (i.e., biofilm formation ability). Strains 168 L, RM48, XLW-2, and J show low virulence and strains 232, 7448, 7422, 168, NJ, and LH show high virulence, as determined through animal challenge experiments, complemented with in vitro tracheal mucosa infection tests. These 10 strains with known virulence were then subjected to classification via multilocus sequence typing (MLST) with three housekeeping genes, P146-based genotyping, and multilocus variable-number tandem-repeat analysis (MLVA) of 13 loci. MLST and P146-based genotyping identified 168, 168 L, NJ, and RM48 as the same type and clustered them in a single branch. MLVA assigned a different sequence type to each strain. Simpson's index of diversity indicates a higher discriminatory ability for MLVA. However, no statistically significant correlation was found between genotypes and virulence. Furthermore, we investigated the correlation between virulence and biofilm formation ability. The strains showing high virulence demonstrate strong biofilm formation ability, while attenuated strains show low biofilm formation ability. Pearson correlation analysis revealed a significant positive correlation between biofilm formation ability and virulence. To conclude, there was no association between virulence and our genotyping data, but virulence was found to be significantly associated with the biofilm formation ability of M. hyopneumoniae.

Virulence and Inoculation Route Influence the Consequences of Mycoplasma hyorhinis Infection in Bama Miniature Pigs.

Mycoplasma hyorhinis is a widespread pathogen in pig farms worldwide. Although the majority of M. hyorhinis-colonized pigs have no apparent clinical disease, the pathogen can induce diseases such as polyserositis, arthritis, and eustachitis in some cases. To explore the mechanisms for the occurrence of these diseases, we challenged 4 groups of Bama miniature pigs with M. hyorhinis isolated from pigs without clinical symptoms (non-clinical origin [NCO] strain) or with typical clinical symptoms (clinical origin [CO] strain) and investigated the impacts of different strains and inoculation routes (intranasal [IN], intravenous [IV] + intraperitoneal [IP], and IV+IP+IN) on disease induction. Another group of pigs was set as a negative control. Pigs inoculated with the CO strain through a combined intravenous and intraperitoneal (IV+IP) route showed a significant decrease in average daily weight gain (ADWG), serious joint swelling, and lameness compared with the pigs in the negative-control group. Furthermore, this group developed moderate-to-severe pericarditis, pleuritis, peritonitis, and arthritis, as well as high levels of IgG and IgM antibodies. Pigs inoculated IV+IP with the NCO strain developed less marked clinical, pathological changes and a weaker specific antibody response compared with the pigs inoculated with the CO strain. The challenging results of the NCO strain via different routes (IV+IP, IV+IP+IN, and IN) indicated that the combined route (IV+IP) induced the most serious disease compared to the other inoculation routes. Intranasal inoculation induced a smaller decrease in ADWG without obvious polyserositis or arthritis. These data suggest that differences in both strain virulence and inoculation route affect the consequences of M. hyorhinis infection. IMPORTANCE Mycoplasma hyorhinis is a widespread pathogen in pig farms worldwide. The mechanisms or conditions that lead to the occurrence of disease in M. hyorhinis-infected pigs are still unknown. The objective of this study was to evaluate the impact of differences in the virulence of strain and the inoculation route on the consequences of M. hyorhinis infection.

Rapid and ultra-sensitive detection of African swine fever virus antibody on site using QDM based-ASFV immunosensor (QAIS).

African swine fever (ASF) is a swine viral disease that could cause highly contagious and extremely high mortality, causing huge economic losses to the pig industry. As there is currently no vaccine and effective treatment methods. Therefore, early monitoring is one of the most important solutions to prevent and control ASF. In this study, the dual QDM recombinant virus protein 30 and 54 (P30 and P54) probes and pre-incubation in vitro were proposed for the first time as QDM based-ASFV immunosensor (QAIS) for the ultra-sensitive quantitative detection of ASFV antibodies in serum. In the range from serum dilution of 1:1000 to 1:64000, it showed a good linear relationship (R2 = 0.9947), and its detection sensitivity was 1:64000 dilution. Compared with commercial enzyme-linked immunosorbent assay (ELISA) and colloidal gold immunochromatographic strip (CGICS), its detection sensitivity was improved by at least one order of magnitude and four orders of magnitude respectively. In addition, the whole ASFV antibody screening test can be completed in 25 min with simple operation. The performance and practicability of the established QAIS sensor have been verified by ASF-ELISA kit, and its coincidence rate was as high as 98.7% in 151 clinical samples. We firmly believe that the proposed QAIS sensor could potentially be applied to point-of-care testing (POCT) for quantitative ASFV antibody in pig farms.

Fructose-1,6-bisphosphate aldolase encoded by a core gene of Mycoplasma hyopneumoniae contributes to host cell adhesion.

Mycoplasma hyopneumoniae is an important respiratory pathogen that causes great economic losses to the pig industry worldwide. Although some putative virulence factors have been reported, pathogenesis remains poorly understood. Herein, we evaluated the relative abundance of proteins in virulent 168 (F107) and attenuated 168L (F380) M. hyopneumoniae strains to identify virulence-associated factors by two-dimensional electrophoresis (2-DE). Seven proteins were found to be ≥ 1.5-fold more abundant in 168, and protein-protein interaction network analysis revealed that all seven interact with putative virulence factors. Unexpectedly, six of these virulence-associated proteins are encoded by core rather than accessory genomic elements. The most differentially abundant of the seven, fructose-1,6-bisphosphate aldolase (FBA), was successfully cloned, expressed and purified. Flow cytometry demonstrated the surface localisation of FBA, recombinant FBA (rFBA) mediated adhesion to swine tracheal epithelial cells (STEC), and anti-rFBA sera decreased adherence to STEC. Surface plasmon resonance showed that rFBA bound to fibronectin with a moderately strong KD of 469 nM. The results demonstrate that core gene expression contributes to adhesion and virulence in M. hyopneumoniae, and FBA moonlights as an important adhesin, mediating binding to host cells via fibronectin.

Application of a sIgA-ELISA method for differentiation of Mycoplasma hyopneumoniae infected from vaccinated pigs.

In order to evaluate the sIgA-ELISA method reported previously for differentiating Mycoplasma hyopneumoniae (M. hyopneumoniae) infected from vaccinated pigs, dynamics of anti-M. hyopneumoniae secretory IgA (sIgA) antibody secretion in nasal mucus and IgG antibodies in serum from 10 pigs experimentally infected with M. hyopneumoniae or vaccinated with an inactivated vaccine were examined using sIgA-ELISA and a commercial M. hyopneumoniae antibody detection kit (IgG-ELISA), respectively. In addition, nasal swabs and serum samples from 2368 pigs of different ages originating from 10 pig farms with different M. hyopneumoniae infection and vaccination status were examined using the two ELISA. In the experimental model, anti-M. hyopneumoniae IgG antibodies were detected in both, the challenge group and the vaccine group. Anti-M. hyopneumoniae sIgA antibodies were detected in the challenge group from 7 days post challenge onwards, but not in the vaccine group. According to the data obtained from pig farms maintaining administration of inactivated vaccine, the prevalence of anti-M. hyopneumoniae sIgA antibody positive pigs was significantly lower than that of IgG antibody positive pigs. In non-vaccinating herds, the prevalence of sIgA antibodies was correlated with the severity of clinical symptoms typical for porcine enzootic pneumonia. In all suckling pigs, no matter vaccinated or not, the prevalence of anti-M. hyopneumoniae sIgA antibody positives was significantly lower than that of IgG antibody positives. These results prove that the sIgA-ELISA is a valuable method enabling the surveillance of M. hyopneumoniae infections in pig herds without interference due to maternally derived antibodies or antibodies induced by administration of inactivated vaccines.

Establishment and characterization of a telomerase-immortalized porcine bronchial epithelial cell line.

Primary porcine bronchial epithelial cells (PBECs) are an ideal model to study the molecular and pathogenic mechanisms of various porcine respiratory pathogens. However, the short lifespan of primary PBECs greatly limit their application. Here, we isolated and cultured primary PBECs and established immortalized PBECs by transfecting primary PBECs with the pEGFP-hTERT recombinant plasmid containing human telomerase reverse transcriptase (hTERT). Immortalized PBECs (hTERT-PBECs) retained the morphological and functional features of primary PBECs as indicated by cytokeratin 18 expression, telomerase activity assay, proliferation assays, karyotype analysis, and quantitative reverse-transcriptase polymerase chain reaction. Compared to primary PBECs, hTERT-PBECs had higher telomerase activity, extended replicative lifespan, and displayed enhanced proliferative activity. Moreover, this cell line is not transformed in vitro and does not exhibit a malignant phenotype in vivo, suggesting that it can be safely used in further studies. Besides, hTERT-PBECs were susceptible to swine influenza virus of H3N2 subtype and porcine circovirus type 2. In conclusion, the immortalized hTERT-PBECs represent a valuable in vitro model, which can be widely used in the study of porcine respiratory pathogenic infections.

Quantifying the influences of various ecological factors on land surface temperature of urban forests.

Identifying factors that influence the land surface temperature (LST) of urban forests can help improve simulations and predictions of spatial patterns of urban cool islands. This requires a quantitative analytical method that combines spatial statistical analysis with multi-source observational data. The purpose of this study was to reveal how human activities and ecological factors jointly influence LST in clustering regions (hot or cool spots) of urban forests. Using Xiamen City, China from 1996 to 2006 as a case study, we explored the interactions between human activities and ecological factors, as well as their influences on urban forest LST. Population density was selected as a proxy for human activity. We integrated multi-source data (forest inventory, digital elevation models (DEM), population, and remote sensing imagery) to develop a database on a unified urban scale. The driving mechanism of urban forest LST was revealed through a combination of multi-source spatial data and spatial statistical analysis of clustering regions. The results showed that the main factors contributing to urban forest LST were dominant tree species and elevation. The interactions between human activity and specific ecological factors linearly or nonlinearly increased LST in urban forests. Strong interactions between elevation and dominant species were generally observed and were prevalent in either hot or cold spots areas in different years. In conclusion, quantitative studies based on spatial statistics and GeogDetector models should be conducted in urban areas to reveal interactions between human activities, ecological factors, and LST.

The effects of Mycoplasma hyopneumoniae on porcine circovirus type 2 replication in vitro PK-15 cells.

Porcine circovirus type 2 (PCV2) is the causative agent of postweaning multisystemic wasting syndrome (PMWS). Mycoplasma hyopneumoniae (Mhp) is a very well-known co-factor that potentially enhances PCV2 replication and thus the development of PMWS. However, co-infection with Mhp and PCV2 in vivo under different conditions can produce divergent clinical signs and lesions. In this study, PCV2 replication could be enhanced by subsequent co-inoculation with Mhp (PCV2+Mhp) in a time and dose dependent method, but not by prior (Mhp+PCV2) or simultaneous (Mhp/PCV2) co-inoculation. Furthermore, different magnitudes of PCV2-infected cells, varying from 150% ± 14% to 351% ± 28%, were detected when co-infected with different Mhp strains. The relative percentage of PCV2-infected cells greatly decreased from 351% ± 28 to 141% ± 18 when the Mhp strain was treated with UV light for 12 h. These results offer the evidences to better understand the complex clinical syndromes in Mhp/PCV2 co-infection cases, and the occurrence of PMWS.

Monoclonal Antibodies Against Porcine sIgA and Their Use in Immunohistochemistry.

Secretory IgA (sIgA) is known as the predominant immunoglobulin in the mucosal system. It prevents pathogens from invading an animal's body through mucosa, making homeostasis. However, few studies examining the secretion of sIgA in mucosal-associated tissues of porcines based on immunohistochemistry methods have been done. In this study, BALB/c mice were immunized with porcine sIgA and the splenocytes were then fused with myeloma cells. Finally, three hybridoma cell lines secreting monoclonal antibody (MAb) against porcine sIgA were obtained. All three MAbs had no cross-reaction with porcine IgG confirmed by Western blot analysis. Furthermore, lungs, tracheas, and intestines were collected from healthy porcines to prepare tissue slices, followed by incubation with the MAb produced in this study. The results showed that sIgA existing in respiratory and digestive systems could be detected by this newly produced MAb. These generated MAbs against porcine sIgA might have a potential use in mucosal research of porcines.

Effects of rapid urban sprawl on urban forest carbon stocks: integrating remotely sensed, GIS and forest inventory data.

Research on the effects of urban sprawl on carbon stocks within urban forests can help support policy for sustainable urban design. This is particularly important given climate change and environmental deterioration as a result of rapid urbanization. The purpose of this study was to quantify the effects of urban sprawl on dynamics of forest carbon stock and density in Xiamen, a typical city experiencing rapid urbanization in China. Forest resource inventory data collected from 32,898 patches in 4 years (1972, 1988, 1996 and 2006), together with remotely sensed data (from 1988, 1996 and 2006), were used to investigate vegetation carbon densities and stocks in Xiamen, China. We classified the forests into four groups: (1) forest patches connected to construction land; (2) forest patches connected to farmland; (3) forest patches connected to both construction land and farmland and (4) close forest patches. Carbon stocks and densities of four different types of forest patches during different urbanization periods in three zones (urban core, suburb and exurb) were compared to assess the impact of human disturbance on forest carbon. In the urban core, the carbon stock and carbon density in all four forest patch types declined over the study period. In the suburbs, different urbanization processes influenced forest carbon density and carbon stock in all four forest patch types. Urban sprawl negatively affected the surrounding forests. In the exurbs, the carbon stock and carbon density in all four forest patch types tended to increase over the study period. The results revealed that human disturbance played the dominant role in influencing the carbon stock and density of forest patches close to the locations of human activities. In forest patches far away from the locations of human activities, natural forest regrowth was the dominant factor affecting carbon stock and density.

Assessment of runoff and sediment yields using the AnnAGNPS model in a Three-Gorge watershed of China.

Soil erosion has been recognized as one of the major threats to our environment and water quality worldwide, especially in China. To mitigate nonpoint source water quality problems caused by soil erosion, best management practices (BMPs) and/or conservation programs have been adopted. Watershed models, such as the Annualized Agricultural Non-Point Source Pollutant Loading model (AnnAGNPS), have been developed to aid in the evaluation of watershed response to watershed management practices. The model has been applied worldwide and proven to be a very effective tool in identifying the critical areas which had serious erosion, and in aiding in decision-making processes for adopting BMPs and/or conservation programs so that cost/benefit can be maximized and non-point source pollution control can be achieved in the most efficient way. The main goal of this study was to assess the characteristics of soil erosion, sediment and sediment delivery of a watershed so that effective conservation measures can be implemented. To achieve the overall objective of this study, all necessary data for the 4,184 km(2) Daning River watershed in the Three-Gorge region of the Yangtze River of China were assembled. The model was calibrated using observed monthly runoff from 1998 to 1999 (Nash-Sutcliffe coefficient of efficiency of 0.94 and R(2) of 0.94) and validated using the observed monthly runoff from 2003 to 2005 (Nash-Sutcliffe coefficient of efficiency of 0.93 and R(2) of 0.93). Additionally, the model was validated using annual average sediment of 2000-2002 (relative error of -0.34) and 2003-2004 (relative error of 0.18) at Wuxi station. Post validation simulation showed that approximately 48% of the watershed was under the soil loss tolerance released by the Ministry of Water Resources of China (500 t·km(-2)·y(-1)). However, 8% of the watershed had soil erosion of exceeding 5,000 t·km(-2)·y(-1). Sloping areas and low coverage areas are the main source of soil loss in the watershed.