Effect of early restrictive fluid resuscitation on inflammatory and immune factors in patients with severe pelvic fracture.

PURPOSE: To study the effect of early restrictive fluid resuscitation (EFR) on inflammatory and immune factors in patients with severe pelvic fracture (SPF). METHODS: A total of 174 SPF patients in the Department of Orthopaedics, the First Affiliated Hospital of Chengdu Medical College from July 2015 to June 2018 were involved in this study and divided into EFR group (n = 87) and control group (n = 87) using the random number table method. Conventional fluid resuscitation (CFR) was performed in control group, and EFR was performed in EFR group. The incidences of acute respiratory distress syndrome (ARDS) and multiple organ dysfunction syndrome (MODS) during rescue, successful rescue rate, blood transfusion volume, fluid input, and resuscitation time were compared between the two groups. The parameters including prothrombin time (PT), hematocrit (HCT), platelet (PLT) and blood lactate (BL) at the 4th hour after fluid resuscitation were recorded. The levels of inflammatory factors (TNF-α, IL-6, CRP) and immune factors (CD3+, CD4+, CD8+, CD4+/CD8+) were compared between the two groups before treatment and 7 days after treatment. The revised acute physiologic and chronic health evaluation system and the sequential organ failure assessment scores were adopted for evaluation before treatment and 7 days after treatment. RESULTS: The incidences of ARDS and MODS during rescue in EFR group were significantly lower than those in control group (p=0.015 and 0.010 respectively), and the successful rescue rate in EFR group was significantly higher than that in control group (p = 0.011). The blood transfusion volume, fluid input, resuscitation time in EFR group were significantly lower than those in control group (p = 0.016, 0.002 and 0.001 respectively). At the 4th hour after fluid resuscitation, PT and BL in EFR group were significantly lower than those in control group (p = 0.021 and 0.003 respectively), while HCT and PLT in EFR group were significantly higher than those in control group (p = 0.016 and 0.021 respectively). On day 7 after treatment, TNF-α, IL-6, CRP and CD8+ in EFR group were significantly lower than those in control group (p = 0.003, 0.004, 0.007 and 0.003 respectively), while CD3+, CD4+ and CD4+/CD8+ in EFR group were significantly higher than those in control group (p = 0.004, 0.000, 0.007 respectively). On day 7 after treatment, the revised acute physiologic and chronic health evaluation (APACHE) system and the sequential organ failure assessment (SOFA) scores in EFR group were significantly lower than those in control group. CONCLUSION: EFR can effectively eliminate inflammatory factors, improve immune function, maintain the stability of blood components, reduce the incidences of ARDS and MODS, and elevate the successful rescue rate in patients with SPF.

Salinity affects microbial function genes related to nutrient cycling in arid regions.

Introduction: Salinization damages soil system health and influences microbial communities structure and function. The response of microbial functions involved in the nutrient cycle to soil salinization is a valuable scientific question. However, our knowledge of the microbial metabolism functions in salinized soil and their response to salinity in arid desert environments is inadequate. Methods: Here, we applied metagenomics technology to investigate the response of microbial carbon (C), nitrogen (N), phosphorus (P), and sulfur (S) cycling and the key genes to salinity, and discuss the effects of edaphic variables on microbial functions. Results: We found that carbon fixation dominated the carbon cycle. Nitrogen fixation, denitrification, assimilatory nitrate reduction (ANRA), and nitrogen degradation were commonly identified as the most abundant processes in the nitrogen cycle. Organic phosphorus dissolution and phosphorus absorption/transport were the most enriched P metabolic functions, while sulfur metabolism was dominated by assimilatory sulfate reduction (ASR), organic sulfur transformation, and linkages between inorganic and organic sulfur transformation. Increasing salinity inhibited carbon degradation, nitrogen fixation, nitrogen degradation, anammox, ANRA, phosphorus absorption and transport, and the majority of processes in sulfur metabolism. However, some of the metabolic pathway and key genes showed a positive response to salinization, such as carbon fixation (facA, pccA, korAB), denitrification (narG, nirK, norBC, nosZ), ANRA (nasA, nirA), and organic phosphorus dissolution processes (pstABCS, phnCD, ugpAB). High salinity reduced the network complexity in the soil communities. Even so, the saline microbial community presented highly cooperative interactions. The soil water content had significantly correlations with C metabolic genes. The SOC, N, and P contents were significantly correlated with C, N, P, and S network complexity and functional genes. AP, NH4+, and NO3- directly promote carbon fixation, denitrification, nitrogen degradation, organic P solubilization and mineralization, P uptake and transport, ASR, and organic sulfur transformation processes. Conclusion: Soil salinity in arid region inhibited multiple metabolic functions, but prompted the function of carbon fixation, denitrification, ANRA, and organic phosphorus dissolution. Soil salinity was the most important factor driving microbial functions, and nutrient availability also played important roles in regulating nutrient cycling.

Structural Characteristics and Assembly Mechanisms of Soil Microbial Communities under Water-Salt Gradients in Arid Regions.

Exploring the structural characteristics of arid soil microbial communities and their assembly mechanisms is important for understanding the ecological characteristics of arid zone soils and promoting ecological restoration. In this study, we used Illumina high-throughput sequencing technology to study soils in the arid zone of the Lake Ebinur basin, determined the differences among soil microbial community structures in the study area under different water-salt gradients, and investigated the effects of environmental factors on microbial community structure and assembly mechanisms. The results show the following: the microbial community alpha diversity exhibited a significantly higher low water-salt gradient (L) than high water-salt gradient (H) and medium water-salt gradient (M). The pH was most strongly correlated with soil microbial community structure, where the alpha diversity indices of the bacterial community and fungal community were significantly negatively correlated with pH, and the Bray-Curtis distance of bacterial community was significantly positively correlated with pH (p < 0.05). The complexity of bacterial community co-occurrence networks showed a significantly higher L than H and M, and the complexity of fungal community co-occurrence network showed a significantly lower L than H and M. The cooperative relationship of H and M in the co-occurrence networks was stronger than that of the L, and the key species of the microbial co-occurrence network were different under different water-salt gradients. Stochastic processes dominated the assembly mechanism of the microbial community structure of soil, and the explanation rates of deterministic and stochastic processes were different under different water-salt gradients, with the highest explanation rate of stochastic processes on the L accounting for more than 90%. In summary, the soil microbial community structure and assembly mechanisms significantly differed across water-salt gradients, and these findings can help provide a reference for further research on soil microbiology in arid zones.

Prediction of spatial distribution characteristics of ecosystem functions based on a minimum data set of functional traits of desert plants.

The relationship between plant functional traits and ecosystem function is a hot topic in current ecological research, and community-level traits based on individual plant functional traits play important roles in ecosystem function. In temperate desert ecosystems, which functional trait to use to predict ecosystem function is an important scientific question. In this study, the minimum data sets of functional traits of woody (wMDS) and herbaceous (hMDS) plants were constructed and used to predict the spatial distribution of C, N, and P cycling in ecosystems. The results showed that the wMDS included plant height, specific leaf area, leaf dry weight, leaf water content, diameter at breast height (DBH), leaf width, and leaf thickness, and the hMDS included plant height, specific leaf area, leaf fresh weight, leaf length, and leaf width. The linear regression results based on the cross-validations (FTEIW - L, FTEIA - L, FTEIW - NL, and FTEIA - NL) for the MDS and TDS (total data set) showed that the R2 (coefficients of determination) for wMDS were 0.29, 0.34, 0.75, and 0.57, respectively, and those for hMDS were 0.82, 0.75, 0.76, and 0.68, respectively, proving that the MDSs can replace the TDS in predicting ecosystem function. Then, the MDSs were used to predict the C, N, and P cycling in the ecosystem. The results showed that non-linear models RF and BPNN were able to predict the spatial distributions of C, N and P cycling, and the distributions showed inconsistent patterns between different life forms under moisture restrictions. The C, N, and P cycling showed strong spatial autocorrelation and were mainly influenced by structural factors. Based on the non-linear models, the MDSs can be used to accurately predict the C, N, and P cycling, and the predicted values of woody plant functional traits visualized by regression kriging were closer to the kriging results based on raw values. This study provides a new perspective for exploring the relationship between biodiversity and ecosystem function.

Effects of plant diversity and abiotic factors on the multifunctionality of an arid desert ecosystem.

Many studies suggest that species diversity and abiotic factors promote ecosystem multifunctionality. However, whether ecosystem multifunctionality is impacted by phylogenetic diversity remains controversial. The present study tested this in an arid desert ecosystem in Ebinur Lake Basin using soil C:N ratio, soil pH, and soil salinity as abiotic factors, and species diversity and phylogenetic diversity as indicators of plant diversity. The effects of plant diversity and abiotic factors on single ecosystem functions (nutrient cycling, carbon stocks, water regulation, and wood production) and ecosystem multifunctionality were studied. We used structural equation modeling to assess the relationships among different functional groups and factors. The results showed that: (1) abiotic factors, particularly pH and C:N ratio in soil, had the strongest positive impact on multifunctionality (P < 0.001). The phylogenetic diversity and species diversity showed inconsistent changes, and their contribution to multifunctionality were not outstanding. (2) Abiotic factors were closely related to different ecosystem functions. Soil C:N had a significant positive effect on carbon stocks (P < 0.001), with an effect index of 0.89. Soil pH significantly enhanced nutrient cycling and water regulation. The role of plant diversity varied with the combination of different ecosystem functions. Phylogenetic diversity and species diversity influenced wood production, but showed opposite functions. (3) The importance of four single-ecosystem functions in an arid region was ranked as follows: carbon stocks > water regulation > nutrient cycling > wood production, emphasizing the importance of carbon elements in these ecosystems. These results improve our understanding of the drivers of multifunctionality in arid ecosystems, facilitating the elucidation of the influence of abiotic factors and phylogenetic diversity.

Discriminating ecological processes affecting different dimensions of α- and ß-diversity in desert plant communities.

Understanding the spatial distribution of plant diversity and its drivers are major challenges in biogeography and conservation biology. Integrating multiple facets of biodiversity (e.g., taxonomic, phylogenetic, and functional biodiversity) may advance our understanding on how community assembly processes drive the distribution of biodiversity. In this study, plant communities in 60 sampling plots in desert ecosystems were investigated. The effects of local environment and spatial factors on the species, functional, and phylogenetic α- and ß-diversity (including turnover and nestedness components) of desert plant communities were investigated. The results showed that functional and phylogenetic α-diversity were negatively correlated with species richness, and were significantly positively correlated with each other. Environmental filtering mainly influenced species richness and Rao quadratic entropy; phylogenetic α-diversity was mainly influenced by dispersal limitation. Species and phylogenetic ß-diversity were mainly consisted of turnover component. The functional ß-diversity and its turnover component were mainly influenced by environmental factors, while dispersal limitation dominantly effected species and phylogenetic ß-diversity and their turnover component of species and phylogenetic ß-diversity. Soil organic carbon and soil pH significantly influenced different dimensions of α-diversity, and soil moisture, salinity, organic carbon, and total nitrogen significantly influenced different dimensions of α- and ß-diversity and their components. Overall, it appeared that the relative influence of environmental and spatial factors on taxonomic, functional, and phylogenetic diversity differed at the α and ß scales. Quantifying α- and ß-diversity at different biodiversity dimensions can help researchers to more accurately assess patterns of diversity and community assembly.

Impacts of plant and soil stoichiometry on species diversity in a desert ecosystem.

Plant and soil stoichiometric ratios can be used to explain changes in the structural and functional characteristics of plant communities. Exploring the relationships between the stoichiometric ratios and plant diversity is helpful to further elucidate the effects of soil and nutrient constraints on community vegetation. However, such studies remain poorly understood in desert ecosystems. In this study, we analysed the effects of soil moisture and salt content on soil and leaf stoichiometry, species diversity and their relationships in the desert ecosystem of the Ebinur Lake basin. The results showed that: (i) Compared with the low soil moisture and salinity (SW2) environment, the soil and leaf C, N, P contents and soil stoichiometric ratios were larger in the high soil moisture and salinity (SW1) environment, and the leaf stoichiometric ratios were smaller. (ii) In SW1 environment, species diversity was negatively correlated with soil C:N and C:P, but weakly correlated with soil stoichiometric ratios in SW2 environment. In addition, the relationships between it and leaf stoichiometric ratios were reversed in different moisture and salinity environments. (iii) Structural equation modelling showed that leaf C:P, C:N and soil C:P had strong effects on species diversity. This research aims to provide a scientific reference for maintaining plant diversity, vegetation reconstruction and ecosystem restoration in desert areas, and enrich the ecological stoichiometric theory of desert ecosystems.

Predicting spatial variability of species diversity with the minimum data set of soil properties in an arid desert riparian forest.

Species diversity has spatial heterogeneity in ecological systems. Although a large number of studies have demonstrated the influence of soil properties on species diversity, most of them have not considered their spatial variabilities. To remedy the knowledge gap, a 1 ha (100 m × 100 m) plots of arid desert riparian forest was set up in the Ebinur Wetland Nature Reserve (ELWNR) in the NW China. Then, the minimum data set of soil properties (soil MDS) was established using the Principal Component Analysis (PCA) and the Norm Value Determination to represent the total soil property data set (soil TDS). The Geo-statistics and two models (i.e., Random Forest/RF and Multiple Linear Regression/MLR) were used to measure the spatial variability of species diversity, and predict its spatial distribution by the soil MDS, respectively. The results showed that the soil MDS was composed of soil salt content (SSC), soil total phosphorus (STP), soil available phosphorus (SAP), soil organic carbon (SOC) and soil nitrate nitrogen (SNN); which represented the soil TDS perfectly (R2 = 0.62). Three species diversity indices (i.e., Shannon-Wiener, Simpson and Pielou indices) had a high spatial dependence (C0/(C0+C)< 25%; 0.72 m ≤ range≤ 0.77 m). Ordinary kriging distribution maps showed that the spatial distribution pattern of species diversity predicted by RF model was closer to its actual distribution compared with MLR model. RF model results suggested that the soil MDS had significant effect on spatial distribution of Shannon-Wiener, Simpson and Pielou indices (Varex = 56%, 49% and 36%, respectively). Among all constituents, SSC had the largest contribution on the spatial variability of species diversity (nearly 10%), while STP had least effect (< 5.3%). We concluded that the soil MDS affected spatial variability of species diversity in arid desert riparian forests. Using RF model can predict spatial variability of species diversity through soil properties. Our work provided a new case and insight for studying the spatial relationship between soil properties and plant species diversity.

Different contributions of plant diversity and soil properties to the community stability in the arid desert ecosystem.

As a one of the focuses of ecological research, understanding the regulation of plant diversity on community stability is helpful to reveal the adaption of plant to environmental changes. However, the relationship between plant diversity and community stability is still controversial due to the scale effect of its influencing factors. In this study, we compared the changes in community stability and different plant diversity (i.e., species, functional, and phylogenetic diversities) between three communities (i.e., riparian forest, ecotone community, and desert shrubs), and across three spatial scales (i.e., 100, 400, and 2500 m2), and then quantified the contribution of soil properties and plant diversity to community stability by using structural equation model (SEM) in the Ebinur Lake Basin Nature Reserve of the Xinjiang Uygur Autonomous Region in the NW China. The results showed that: (1) community stability differed among three communities (ecotone community > desert shrubs > riparian forest). The stability of three communities all decreased with the increase of spatial scale (2) species diversity, phylogenetic richness and the mean pairwise phylogenetic distance were higher in ecotone community than that in desert shrubs and riparian forest, while the mean nearest taxa distance showed as riparian forest > ecotone community > desert shrubs. (3) Soil ammonium nitrogen and total phosphorus had the significant direct negative and positive effects on the community stability, respectively. Soil ammonium nitrogen and total phosphorus also indirectly affected community stability by adjusting plant diversity. The interaction among species, functional and phylogenetic diversities also regulated the variation of community stability across the spatial scales. Our results suggested that the effect of plant diversities on community stability were greater than that of soil factors. The asynchronous effect caused by the changes in species composition and functional traits among communities had a positive impact on the stability. Our study provided a theoretical support for the conservation and management of biodiversity and community functions in desert areas.

Characteristics and driving mechanisms of species beta diversity in desert plant communities.

Species dissimilarity (beta diversity) primarily reflects the spatio-temporal changes in the species composition of a plant community. The correlations between ß diversity and environmental factors and spatial distance can be used to explain the magnitudes of environmental filtering and dispersal. However, little is known about the relative roles and importance of neutral and niche-related factors in the assemblage of plant communities with different life forms in deserts. We found that in desert ecosystems, the ß diversity of herbaceous plants was the highest, followed by that of shrubs and trees. The changes in the ß diversity of herbs and shrubs had stronger correlations with the environment, indicating that community aggregation was strongly affected by niche processes. The soil water content and salt content were the key environmental factors affecting species distributions of the herb and shrub layers, respectively. Spatial distance explained a larger amount of the variation in tree composition, indicating that dispersal limitation was the main factor affecting the construction of the tree layer community. The results suggest that different life forms may determine the association between organisms and the environment. These findings suggest that the spatial patterns of plant community species in the Ebinur Lake desert ecosystem are the result of the combined effects of environmental filtering and dispersal limitation.

Structure and driving factors of the soil microbial community associated with Alhagi sparsifolia in an arid desert.

Environmental properties are important factors in structuring soil microbial communities. The primary driving factors vary in different ecosystems. In the present work, we analyzed the microbial communities of rhizosphere and bulk soils associated with the halophyte Alhagi sparsifolia across three salt/water gradients in the desert area around Ebinur Lake Basin, China, using high-throughput sequencing technology. We found that there were significant differences in soil water content (SWC), soil salinity (SAL), total nitrogen (TN), and total phosphorus (TP) contents between the three water/salt gradients. In the L (low water and salt) plot, Actinobacteria was the most abundant bacterial phylum while Ascomycota was the dominant fungal phylum. The relative abundance of Actinobacteria was negatively correlated with soil pH, soil organic carbon (SOC), TP, and available phosphorus (AP). The abundance of Bacteroidetes was significantly positively correlated with soil SOC, SWC, SAL, pH, TN, and TP (P < 0.05). The abundance of fungal phylum Chytridiomycota was significantly positively correlated with pH (P < 0.01), SWC, AP, and sulfate ion (P < 0.05). SOC and nitrate nitrogen were the main factors impacting the bacterial community, while ammonium nitrogen (NH4+) and TP were the main driving forces for the fungal community. Soil nutrients were the main contributors to the dissimilarities in the bacterial and fungal communities, explaining 48.06% and 44.45% of the variation. SWC, SAL, and pH explained only a small percentage of the microbial community dissimilarity. In conclusion, soil microbial community structure was affected by SWC, SAL, pH, and soil nutrients, with soil nutrients as the main driving factors. Nitrogen has a differential effect on the different microbial communities: bacterial communities of Alhagi sparsifolia were mainly affected by nitrate nitrogen, while fungal communities were mainly driven by ammonium nitrogen.