Explore the vast range of titles available.

PurposeBiological soil crusts (biocrusts) are ubiquitous in arid and semi-arid regions and play many critical roles in soil stabilization and erosion prevention, greatly decreasing soil loss. Although sediments may be completely controlled by well-developed biocrusts, runoff loss is observed. Consequently, it is important to study how biocrusts resist runoff erosion in different developmental stages to evaluate and manage water erosion.Materials and methodsIn the Loess Plateau Region, we sampled 32 biocrust plots representing eight stages of biocrust development and 5 slope cropland soil plots as bare soil control plots. We then used a rectangular open channel hydraulic flume to test the effects of biocrust development on runoff erosion.Results and discussionAs expected, the establishment of biocrusts enhanced soil stability, and accordingly, soil anti-scourability significantly increased with biocrust development. Biocrusts exhibiting more than 36% or 1.22 g dm−2 of moss coverage or biomass fully protected the soil from runoff erosion. Moreover, soil properties, such as soil organic matter, soil cohesion and soil bulk density, were also important in reducing erosion. The findings indicated that biocrusts inhibited runoff erosion through direct physical protection related to biocrust cover and biomass and through the indirect modification of soil properties. In the early biocrust development stage (when moss cover was less than 36%), cyanobacterial biocrust played a primary role in providing resistance to runoff erosion, with resistance being positively related to cyanobacterial biomass (chlorophyll a) and influenced by soil properties.ConclusionsThe relationship between soil anti-scourability and moss coverage or biomass can be divided into two stages based on a moss cover or biomass threshold. The capacity of biocrusts to resist runoff erosion was limited when moss cover was below the threshold value. Therefore, the stage corresponding to this level of moss cover should be of concern when estimating, predicting and managing water erosion.

Aims Biological soil crusts (biocrusts) play key roles in dryland ecosystems. Examining the effects of different intensities of disturbance on biocrusts and exploring appropriate disturbance levels can provide important information about ecosystem processes and services in drylands. Methods Five disturbance intensities ranging from 10% to 50% based on the percentage of broken biocrusts were implemented to examine the effects of simulated goat trampling on microbial communities; microbial community structure was measured with the phospholipid fatty acid method. Results The effects of disturbance on the biocrusts were closely related to disturbance intensity. Surprisingly, moderate disturbance had a weak effect on total biocrust coverage but increased cyanobacterial coverage by 2 ~ 3%. Consequently, there was an increase in total N, a reduction in the C/N ratio and improvements in soil moisture, and these effects led to 13 ~ 21% and 5 ~ 6% increases in microbial biomass and diversity, respectively, compared with those in undisturbed biocrusts. However, high-intensity disturbance substantially reduced biocrust coverage and microbial abundance. Conclusions The study supports the intermediate disturbance hypothesis and suggests that moderate disturbance has positive effects on the microbial communities of biocrusts. These findings provide vital information for the ecological management of drylands.

Background Lung ischemia-reperfusion (IR) injury after transplantation as well as acute shortage of suitable donor lungs are two critical issues impacting lung transplant patients. This study investigates the anti-inflammatory and immunomodulatory role of human mesenchymal stromal cells (MSCs) and MSC-derived extracellular vesicles (EVs) to attenuate lung IR injury and improve of ex-vivo lung perfusion (EVLP)-mediated rehabilitation in donation after circulatory death (DCD) lungs. Methods C57BL/6 wild-type (WT) mice underwent sham surgery or lung IR using an in vivo hilar-ligation model with or without MSCs or EVs. In vitro studies used primary iNKT cells and macrophages (MH-S cells) were exposed to hypoxia/reoxygenation with/without co-cultures with MSCs or EVs. Also, separate groups of WT mice underwent euthanasia and 1 h of warm ischemia and stored at 4  ° C for 1 h followed by 1 h of normothermic EVLP using Steen solution or Steen solution containing MSCs or EVs. Results Lungs from MSCs or EV-treated mice had significant attenuation of lung dysfunction and injury (decreased edema, neutrophil infiltration and myeloperoxidase levels) compared to IR alone. A significant decrease in proinflammatory cytokines (IL-17, TNF-α, CXCL1 and HMGB1) and upregulation of keratinocyte growth factor, prostaglandin E2 and IL-10 occurred in the BAL fluid from MSC or EV-treated mice after IR compared to IR alone. Furthermore, MSCs or EVs significantly downregulated iNKT cell-produced IL-17 and macrophage-produced HMGB1 and TNF-α after hypoxia/reoxygenation. Finally, EVLP of DCD lungs with Steen solution including MSCs or EVs provided significantly enhanced protection versus Steen solution alone. Co-cultures of MSCs or EVs with lung endothelial cells prevents neutrophil transendothelial migration after exposure to hypoxia/reoxygenation and TNF-α/HMGB1 cytomix. Conclusions These results suggest that MSC-derived EVs can attenuate lung inflammation and injury after IR as well as enhance EVLP-mediated reconditioning of donor lungs. The therapeutic benefits of EVs are in part mediated through anti-inflammatory promoting mechanisms via attenuation of immune cell activation as well as prevention of endothelial barrier integrity to prevent lung edema. Therefore, MSC-derived EVs offer a potential therapeutic strategy to treat post-transplant IR injury as well as rehabilitation of DCD lungs.

Ammonia fuel is expected to emerge as an effective alternative to fossil fuels due to its zero-carbon nature, high-efficiency storage and transportation advantages, and extensive industrial manufacturing infrastructure. This study discussed the impacts of compression ratio and injection timing on combustion and emission characteristics of an ammonia/diesel dual-fuel (ADDF) engine using numerical simulation. Results indicated that the corresponding optimal indicated thermal efficiency (ITE) continuously increases with an increasing compression ratio. When the compression ratio is 15:1, the injection timing corresponding to the maximum indicated thermal efficiency is −18 °CA after top dead center (ATDC). When the compression ratio ranged from 16:1 to 19:1, the corresponding optimal ITE was achieved at a retarded injection timing of −12 °CA ATDC. At a compression ratio of 19:1, the optimal ITE reached 47.9%. The in-cylinder formation regions of nitrous oxide (N2O) are closely correlated with NH3, NO, and temperature distributions, being primarily located at the interface between high-concentration regions of unburned NH3 and NO. Under the comprehensive impact of increased compression ratio and advanced injection timing, both N2O and unburned NH3 emissions show a tendency of increasing first and then decreasing, while NOx emissions demonstrated a monotonically increasing behavior.

Adenosine inhibits the activation of most immune cells and platelets. Selective adenosine A2A receptor (A2AR) agonists such as regadenoson (RA) reduce inflammation in most tissues, including lungs injured by hypoxia, ischemia, transplantation, or sickle cell anemia, principally by suppressing the activation of invariant natural killer T (iNKT) cells. The anti-inflammatory effects of RA are magnified in injured tissues due to induction in immune cells of A2ARs and ecto-enzymes CD39 and CD73 that convert ATP to adenosine in the extracellular space. Here we describe the results of a five patient study designed to evaluate RA safety and to seek evidence of reduced cytokine storm in hospitalized COVID-19 patients. Five COVID-19 patients requiring supplemental oxygen but not intubation (WHO stages 4-5) were infused IV with a loading RA dose of 5 μg/kg/h for 0.5 h followed by a maintenance dose of 1.44 μg/kg/h for 6 hours, Vital signs and arterial oxygen saturation were recorded, and blood samples were collected before, during and after RA infusion for analysis of CRP, D-dimer, circulating iNKT cell activation state and plasma levels of 13 proinflammatory cytokines. RA was devoid of serious side effects, and within 24 hours from the start of infusion was associated with increased oxygen saturation (93.8 ± 0.58 vs 96.6 ± 1.08%, P<0.05), decreased D-dimer (754 ± 17 vs 518 ± 98 ng/ml, P<0.05), and a trend toward decreased CRP (3.80 ± 1.40 vs 1.98 ± 0.74 mg/dL, P = 0.075). Circulating iNKT cells, but not conventional T cells, were highly activated in COVID-19 patients (65% vs 5% CD69+). RA infusion for 30 minutes reduced iNKT cell activation by 50% (P<0.01). RA infusion for 30 minutes did not influence plasma cytokines, but infusion for 4.5 or 24 hours reduced levels of 11 of 13 proinflammatory cytokines. In separate mouse studies, subcutaneous RA infusion from Alzet minipumps at 1.44 μg/kg/h increased 10-day survival of SARS-CoV-2-infected K18-hACE2 mice from 10 to 40% (P<0.001). Infused RA is safe and produces rapid anti-inflammatory effects mediated by A2A adenosine receptors on iNKT cells and possibly in part by A2ARs on other immune cells and platelets. We speculate that iNKT cells are activated by release of injury-induced glycolipid antigens and/or alarmins such as IL-33 derived from virally infected type II epithelial cells which in turn activate iNKT cells and secondarily other immune cells. Adenosine released from hypoxic tissues, or RA infused as an anti-inflammatory agent decrease proinflammatory cytokines and may be useful for treating cytokine storm in patients with Covid-19 or other inflammatory lung diseases or trauma.

● Biocrusts are one of the most important components of the land cover in frozen ground regions on the Qinghai–Tibet Plateau, which increased the silt particle content, enhanced field moisture capacity, and reduced soil bulk density. ● Biocrusts significantly increased levels of SOC (22.6−30.8 g kg −1) and TN (2.1−2.8 g kg −1) within the 0–40 cm soil layer, while they had no significant influence on the TP contents. ● Biocrusts also had influence on the stoichiometry characteristics, and the C/N, C/P and N/P ratios of the biocrusts were all higher than that of the bare land, which revealed that biocrusts enhanced the contents of SOC and TN in presuccessional period of biocrusts and reduced the availability of P in their postsuccessional period. Biocrusts (BSCs) are widely distributed in frozen ground regions on the Qinghai-Tibet Plateau, and they are considered an important component of cold ecosystems. However, the specific impacts of BSCs on frozen soil remains relatively unclear. The aim of our study was to clarify the influence of BSCs (light BSCs and dark BSCs in two different succession stages) on the physical properties and ecological stoichiometry characteristics of frozen soil. Our results showed that BSCs increased the silt particle content in 20–40 cm soil layer, leading to a decrease in soil bulk density. And the field water capacity increased about 10%–40% compared to bare land. Additionally, BSCs significantly increased the contents of soil organic carbon (SOC, 22.6–30.8 g kg −1) and total nitrogen (TN, 2.1–2.8 g kg −1) in the upper 40 cm soil layer, both of them were approximately 1.3–2.0 and 1.3–4.0 times higher than those observed in bare land. However, BSCs did not have significant influence on soil total phosphorus (TP). BSCs had a significant impact on the stoichiometric ratios within 40 cm. The C/N ratios of the two types of BSCs ranged from 8.8 to 13.5, the C/P ratios ranged from 6.6 to 13.8, and the N/P ratios ranged from 0.6 to 1.2, which were all higher than those of the bare land. There were no significant differences among the C/N, C/P, and N/P ratios between two types of BSCs. However, the increment of C/P and N/P ratios of dark BSCs were significantly higher than those of light BSCs within 0–30 cm, which indicated that a reduction in the availability of phosphorus during the later stages of BSCs succession. These findings provided a theoretical basis for further research on the ecological functions of BSCs in frozen ground regions.

The succession of biological soil crust (biocrust) may alter soil organic carbon (SOC) stability by affecting SOC fractions in arid and semi-arid regions. In the study, the SOC fractions were measured including soil easily oxidizable carbon (SEOC), soil microbial biomass carbon (SMBC), soil water soluble carbon (SWSC), and soil mineralizable carbon (SMC) at the Loess Plateau of China by using four biocrusts. The results show that SOC fractions in the biocrust layer were consistently higher than that in the subsoil layers. The average SOC content of moss crust was approximately 1.3–2.0 fold that of three other biocrusts. Moss crusts contain the lowest ratio of SEOC to SOC compared with other biocrusts. The ratio of SMC to SOC was the highest in light cyanobacteria biocrust and the lowest in moss crust, but no difference was observed in SMBC to SOC and SWSC to SOC in biocrust layers among four studied biocrusts. The results show that the moss crusts increase the accumulation of organic carbon into soil and reduce the ratio of SEOC to SOC and SMC to SOC. Together, these findings indicate that moss crusts increase the SOC stability and have important implications that SOC fractions and mineralization amount are good indicators for assessing the SOC stability.

We recently implicated a role for CD4(+) T cells and demonstrated elevated IL-17A expression in lung ischemia-reperfusion (IR) injury. However, identification of the specific subset of CD4(+) T cells and their mechanistic role in IR injury remains unknown. We tested the hypothesis that invariant natural killer T (iNKT) cells mediate lung IR injury via IL-17A signaling. Mice underwent lung IR via left hilar ligation. Pulmonary function was measured using an isolated lung system. Lung injury was assessed by measuring edema (wet/dry weight) and vascular permeability (Evans blue dye). Inflammation was assessed by measuring proinflammatory cytokines in lungs, and neutrophil infiltration was measured by immunohistochemistry and myeloperoxidase levels. Pulmonary dysfunction (increased airway resistance and pulmonary artery pressure and decreased pulmonary compliance), injury (edema, vascular permeability), and inflammation (elevated IL-17A; IL-6; tumor necrosis factor-α; monocyte chemotactic protein-1; keratinocyte-derived chemokine; regulated upon activation, normal T-cell expressed and secreted; and neutrophil infiltration) after IR were attenuated in IL-17A(-/-) and Rag-1(-/-) mice. Anti-IL-17A antibody attenuated lung dysfunction in wild-type mice after IR. Reconstitution of Rag-1(-/-) mice with wild-type, but not IL-17A(-/-), CD4(+) T cells restored lung dysfunction, injury, and inflammation after IR. Lung dysfunction, injury, IL-17A expression, and neutrophil infiltration were attenuated in Jα18(-/-) mice after IR, all of which were restored by reconstitution with wild-type, but not IL-17A(-/-), iNKT cells. Flow cytometry and enzyme-linked immunosorbent spot assay confirmed IL-17A production by iNKT cells after IR. These results demonstrate that CD4(+) iNKT cells play a pivotal role in initiating lung injury, inflammation, and neutrophil recruitment after IR via an IL-17A-dependent mechanism.

The effects of acute hyperglycemia on lung ischemia-reperfusion (IR) injury and the role of receptor for advanced glycation end-products (RAGE) signaling in this process are unknown. The objective of this study was twofold: (1) evaluate the impact of acute hyperglycemia on lung IR injury; and (2) determine if RAGE signaling is a mechanism of hyperglycemia-enhanced IR injury. We hypothesized that acute hyperglycemia worsens lung IR injury through a RAGE signaling mechanism. C57BL/6 wild-type (WT) and RAGE knockout (RAGE (-/-)) mice underwent sham thoracotomy or lung IR (1-h left hilar occlusion and 2-h reperfusion). Acute hyperglycemia was established by dextrose injection 30 minutes before ischemia. Lung injury was assessed by measuring lung function, cytokine expression in bronchoalveolar lavage fluid, leukocyte infiltration, and microvascular permeability via Evans blue dye. Mean blood glucose levels doubled in hyperglycemic mice 30 minutes after dextrose injection. Compared with IR in normoglycemic mice, IR in hyperglycemic mice significantly enhanced lung dysfunction, cytokine expression (TNF-α, keratinocyte chemoattractant, IL-6, monocyte chemotactic protein-1, regulated upon activation, normal T cell expressed and secreted), leukocyte infiltration, and microvascular permeability. Lung injury and dysfunction after IR were attenuated in normoglycemic RAGE (-/-) mice, and hyperglycemia failed to exacerbate IR injury in RAGE (-/-) mice. Thus, this study demonstrates that acute hyperglycemia exacerbates lung IR injury, whereas RAGE deficiency attenuates IR injury and also prevents exacerbation of IR injury in an acute hyperglycemic setting. These results suggest that hyperglycemia-enhanced lung IR injury is mediated, at least in part, by RAGE signaling, and identifies RAGE as a potential, novel therapeutic target to prevent post-transplant lung IR injury.

Biological soil crusts (biocrusts) are ubiquitous living covers in arid and semiarid regions, playing a critical role in soil erosion control in semiarid regions. So far, research separating the multiple mechanisms of erosion control by biocrusts has been limited. It was problematic to link the influence of biocrusts to existing erosion models. In the present study, the response of biocrusts of different successional stages to raindrop erosivity and underlying influences was investigated. Using single drop simulated rainfall, the erosion controlling capacities of biocrusts were analyzed from an energetic perspective. The results showed that biocrusts caused a dramatic improvement of soil erosion resistance, which depended on species composition and increased considerably with higher succession stages. While the accumulated raindrop kinetic energy sustained by dark cyanobacterial crusts was 0.93 J (~15 times higher than that of bare soil), that of 60 % moss covered crusts reached values up to 20.18 J (~342 times higher than that of bare soil) and for 80 % moss covered crusts even 24.59 J were measured. Besides the composition and successional stages, the resistance of biocrusts to raindrop erosivity was related to the substrate soil moisture, soil texture, slope gradients and seasonal variation. The accumulated raindrop kinetic energy measured for cyanobacterial crusts was highest on silty, followed by loamy and sandy soil. For moss-dominated crusts raindrop kinetic energy was highest on sandy, followed by silty and loamy soil. Dry biocrust samples reached significantly higher accumulated raindrop kinetic energies compared to moist biocrusts, whereas the moisture content within moist crusts did not have a significant influence. Erosion resistance increased significantly with higher slope gradients. The resistance capacities of biocrusts during monsoon and post-monsoon were significantly higher than these of pre-monsoon biocrusts. Our results suggest that the influence of biocrusts can be included into erosion models from an energy point of view. The raindrop kinetic energy resistance capacity provides a potential bridge between biocrust succession and soil erodibility in commonly used erosion models.