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In the limited number of studies on biotic resistance in freshwater ecosystems, experimental studies have supported that native plants play a role in resisting exotic plant invasion, but field observations have often reported positive relationships between exotic and native plant richness. To determine the reasons for the lack of evidence supporting biotic resistance in field observations, we surveyed the richness, biomass and coverage of exotic and native aquatic plants in 2801 quadrats at 287 sites in various freshwater ecosystems of China and examined the impacts of scale and environmental factors on the relationships between native and exotic plant richness and performance. At both the site and quadrat scales, we observed a positive correlation between the richness of exotic and native plants. However, at the quadrat scale, high native plant richness was associated with a reduction in the biomass of exotic emergent and floating plants as well as the biomass of exotic submerged plants in low‐nutrient water bodies. An increase in native plant performance, a metric that integrates the biomass and coverage of native plants, was associated with a decrease in both the richness and biomass of exotic plants at both scales. Furthermore, with increasing native plant performance at the quadrat scale, the richness of exotic plants declined more strongly in low‐nutrient water bodies than in high‐nutrient water bodies, and the decline in the biomass of exotic emergent and floating plants was more severe in shallow water than in deep water. Synthesis. Our results indicate that native plant performance is more important than richness for resistance to invasion in freshwater ecosystems, and the strength of biotic resistance is related to environmental factors. This study highlights the importance of environmental variables and multiple native community features and invasibility metrics in field observational studies of invasion. [ABSTRACT FROM AUTHOR]

Prior studies on preferences of native herbivores for native or exotic plants have tested both the enemy release hypothesis and the biotic resistance hypothesis and have reported inconsistent results. The different levels of resistance of native and exotic plants to native herbivores could resolve this controversy, but little attention has been paid to this issue. In this study, we investigated population performance, photosynthesis, leaf nitrogen concentration, and the constitutive and induced resistances of the successful invasive plant, Alternanthera philoxeroides, and its native congener, Alternanthera sessilis, in the presence of three population densities of the grasshopper, Atractomorpha sinensis. When the grasshopper was absent, leaf biomass, total biomass, photosynthesis, and leaf nitrogen concentration of A. philoxeroides were higher than those of A. sessilis. However, the morphological and physiological performances of A. philoxeroides were all decreased more intensively than A. sessilis after herbivory by grasshoppers. Especially as the concentrations of constitutive lignin and cellulose in leaf of A. philoxeroides were higher than A. sessilis, A. philoxeroides exhibited increased leaf lignin concentration to reduce its palatability only at severe herbivore load, whereas, leaf lignin, cellulose, and polyphenolic concentrations of A. sessilis all increased with increasing herbivory pressure, and cellulose and polyphenolic concentrations were higher in A. sessilis than in A. philoxeroides after herbivory. Our study indicated that the capability of the invasive plant to respond to native insect damage was lower than the native plant, and the invasive plant was suppressed more intensively than its native congener by the native insect. Our results support the biotic resistance hypothesis and suggest that native herbivores can constrain the abundance and reduce the adverse effects of invasive species. [ABSTRACT FROM AUTHOR]

Our study aimed to establish and validate a multi-class scoring system for preoperative gastric gastrointestinal stromal tumors (GISTs) risk stratifications based on CT features. 150 gastric GIST patients who underwent contrast-enhanced CT examination and surgical resection from hospital 1 were retrospectively analyzed as the training cohort, and 61 patients from hospitals 2 and 3 were included as the validation cohort. A model was established by logistic regression analysis and weighted to be a scoring model. A calibration test, area under the receiver operating characteristic (ROC) curve (AUC), and cutoff points were determined for the score model. The model was also divided into three score ranges for convenient clinical evaluation. Five CT features were included in the score model, including tumor size (4 points), ill-defined margin (6 points), intratumoral enlarged vessels (5 points), heterogeneous enhancement pattern (4 points), and exophytic or mixed growth pattern (2 points). Then, based on the calibration results, performance was merely assessed as very low and high* risk. The AUCs of the score model for very low risk and high* risk were 0.973 and 0.977, and the cutoff points were 3 points (97.30%, 93.81%) and 7 points (92.19%, 94.19%), respectively. In the validation cohort, the AUCs were 0.912 and 0.972, and the cutoff values were 3 points (92.31%, 85.42%) and 5 points (100%, 87.88%), respectively. The model was stratified into 3 ranges: 0-3 points for very low risk, 4-8 points for low risk, and 9-21 points for high* risk. A concise and practical score system for gastric GISTs risk stratification was proposed., Competing Interests: None., (AJCR Copyright © 2020.)

Objective: To explore the magnetic resonance imaging (MRI) manifestations of early prostatic carcinoma (PCa) in central zone (CZ) ., Methods: A total of 284 cases of PCa were scanned by MRI while 24 cases of carcinoma in 28 PCa focus were in central zone. Their T1WI, T2WI, DWI and ADC value characteristics were analyzed respectively and the completeness of annular low signal between central and peripheral zones were observed. At the same time, 45 cases of PCa were located in peripheral zone (PZ) . Twenty cases of benign prostatic hyperplasia (BPH) were comparatively analyzed. All cases received a histological diagnosis., Results: Most cases of early PCa in CZ demonstrated ill-defined margin, amorphous shape and equal signal intensity on T1WI, low signal intensity on T2WI and high signal intensity on DWI. The mean ADC value for PCa focus was (0.867 ± 0.074)×10(-3) mm(2)/s and PCa foci were enhanced slightly. In these cases, most annular low signals between CZ and PZ were destroyed. The difference of ADC values between PCa in CZ and PZ groups ((0.914 ± 0.066) ×10(-3) mm(2)/s ) had no statistic significance (P > 0.05) , but the ADC values between PCa and BPH in CZ groups ((1.517 ± 0.315) ×10(-3) mm(2)/s ) had statistically significant difference (P < 0.05)., Conclusion: Some reliable diagnostic characteristics on MRI may be used for an early diagnosis of PCa in CZ.

Objective: To evaluate the results of operative treatment of acetabular fractures and to investigate its influence factors., Methods: The clinical data were analyzed retrospectively from 82 patients with acetabular fractures treated between September 2004 and June 2009. Of 82 patients, 65 were male and 17 were female, aged 26-72 years (mean, 38 years). Fractures were caused by traffic accident in 62 cases, by crush in 13 cases, and by falling from height in 7 cases. The time from injury to admission was 30 minutes to 12 days (median, 7.6 hours) in 70 cases, 12 cases were transferred because poor result after 34-67 days of conservative treatment. According to Judet classification, there were 24 cases of posterior wall fracture, 3 cases of posterior column fracture, 1 case of anterior wall fracture, 2 cases of anterior column fracture, 6 cases of transverse fracture, 16 cases of transverse and posterior wall fracture, 4 cases of posterior column and posterior wall fracture, 5 cases of T-type fracture, 3 cases of anterior and posterior hemitransverse fracture, and 18 cases of complete both-column fracture; 24 cases combined with dislocation of the hip. During operation, Kocher-Langenbeck approach was used in 49 cases, anterior ilioinguinal approach in 19 cases, and the combination of anterior and posterior approaches in 14 cases. Reconstructive plate (74 cases) and hollow lag screw (8 cases) internal fixation were used. The function of the hip was evaluated according to the modified Merled'Aubigne-Postel hip score system postoperatively. According to fracture type, age, lower extremity fracture before operation, quality of reduction, timing of surgery, hip dislocation and time of reduction, operative approach, deep vein thrombosis (DVT), and heterotopic ossification (HO), the patients were divided into the groups and the results were compared., Results: Accordance with the Matta X-ray evaluation criteria, anatomic reduction was achieved in 21 cases, good reduction in 37 cases, fair reduction in 16 cases, and poor reduction in 8 cases, and the excellent and good rate was 71%. All the cases were followed up 12-52 months (mean, 34 months). Iatrogenic sciatic nerve injury occurred in 8 cases, infection in 3 cases, HO in 16 cases, DVT in 3 cases, hip posttraumatic arthritis in 12 cases, and avascular necrosis of the femoral head in 9 cases. X-ray examination showed that 80 cases achieved fracture union at 10-24 weeks after operation (mean, 14 weeks) and 2 cases had fracture delayed union at 10 months and 12 months after operation. According to the modified Merled'Aubigne-Postel hip score system, the function of the hip was rated as excellent in 26 cases, good in 32, fair in 20, and poor in 4 at 6 months after operation; the excellent and good rate was 71%. The affecting factors of clinical results of acetabular fractures were fracture type, age, lower extremity fracture before operation, quality of reduction, timing of surgery, hip dislocation and time of reduction (P < 0.05). However the operative approach, DVT, and HO were not affecting factor of the acetabular fractures (P > 0.05)., Conclusion: Operative treatment of acetabular fractures has a satisfying therapeutic effect. Fracture type, age, lower extremity fracture before operation, quality of reduction, timing of surgery, hip dislocation, and time of reduction are risk factors affecting postoperative results.