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Fuel moisture content (FMC), which is the ratio of equivalent water thickness (EWT) to dry matter content (DMC), plays a crucial role in the estimation of vegetation ignition probability and the fire propagation rate. The PROSAIL model can adequately simulate the canopy reflectance of vegetation, with the input of field-measured data into the model ensuring conformity with the ecological rules. If the EWT and DMC can be estimated by an empirical statistical method according to the reflectance spectrum, the universality of the physical model and the efficiency of the empirical statistical method can be considered. In this study, a fast and versatile method is established for estimating FMC based on the EWT, DMC, leaf area index measured data, and the PROSAIL model. The Normalized Difference Infrared Index (NDII) and Normalized Dry Matter Index (NDMI) were obtained from the spectral curves, with the results showing an obvious linear relationship between the NDII and EWT, NDMI, and DMC. Therefore, EWT and DMC can be estimated using the NDII and NDMI. The accuracy of the estimation results is verified to be high. The estimation model can be extended to Landsat 8 data to estimate FMC. The estimated FMC data verified by the measured data showed that R² was 0.743 and the RMSE was 34.2%. The model accuracy was reliable owing to large dynamic changes in the FMC. However, the estimated value of the FMC shifted significantly to the left during this study. The reasons for this are as follows: 1) The field-measured points are not sufficient to support the analysis according to different vegetation types, and the physical and chemical properties of different types are varied, leading to altered simulated spectral curves; 2) The vegetation spectrum is sensitive to the DMC at 1,650 nm, 1,720 nm, and 2,270 nm bands, and the sensitivity near the 1,650 nm and 1,720 nm bands is greater than that at 2,270 nm. However, because the Landsat 8 image does not have a 1,720 nm band, the 2,270 nm band was selected to calculate the NDMI, making the value of the estimated DMC too large, resulting in a small value of the estimated FMC and a significant shift to the left; 3) 1,650 nm and 2,270 nm are not in the central wavelength of the two bands of Landsat 8; therefore, the estimated DMC and FMC are shifted. In addition, the fast and versatile method, which is established based on the EWT, DMC, leaf area index measured data and the PROSAIL model, can realize large-scale and high-precision monitoring of the FMC, providing a scientific reference for forest fire prevention.

Fire-resistant tree species play a crucial role in forest fire prevention, utilizing several physiological and molecular mechanisms to respond to extreme heat stress. Many transcription factors (TFs) and genes are known to be involved in the regulatory network of heat stress response in plants. However, their roles in response to high temperatures induced by fire remain less understood. In this study, we investigated Schima superba, a fire-resistant tree, to elucidate these mechanisms. Leaves of S. superba seedlings were exposed to fire stimulation for 10 s, 30 s, and 1 min, followed by a 24-h recovery period. Fifteen transcriptomes were assembled to identify key molecular and biological pathways affected by high temperatures. Differentially expressed genes (DEGs) analysis revealed essential candidate genes and TFs involved in the heat stress response, including members of the ethylene-responsive factors, WRKY, MYB, bHLH, and Nin-like families. Genes related to heat shock proteins/factors, lipid metabolism, antioxidant enzymes, dehydration responses, and hormone signal transduction were differentially expressed after heat stress and recovery, underscoring their roles in cellular process and recovery after heat stress. This study advances our understanding of plant response and defense strategies against extreme abiotic stresses. [ABSTRACT FROM AUTHOR]

Establishing an efficient PM2.5 prediction model and in-depth knowledge of the relationship between the predictors and PM2.5 in the model are of great significance for preventing and controlling PM2.5 pollution and policy formulation in the Yangtze River Delta (YRD) where there is serious air pollution. In this study, the spatial pattern of PM2.5 concentration in the YRD during 2003–2019 was analyzed by Hot Spot Analysis. We employed five algorithms to train, verify, and test 17 years of data in the YRD, and we explored the drivers of PM2.5 exposure. Our key results demonstrated: (1) High PM2.5 pollution in the YRD was concentrated in the western and northwestern regions and remained stable for 17 years. Compared to 2003, PM2.5 increased by 10–20% in the southeast, southwest, and western regions in 2019. The hot spot for percentage change of PM2.5 was mostly located in the southwest and southeast regions in 2019, while the interannual change showed a changeable spatial distribution pattern. (2) Geographically Weighted Random Forest (GWRF) has great advantages in predicting the presence of PM2.5 in comparison with other models. GWRF not only improves the performance of RF, but also spatializes the interpretation of variables. (3) Climate and human activities are the most important drivers of PM2.5 concentration. Drought, temperature, and temperature difference are the most critical and potentially threatening climatic factors for the increase and expansion of PM2.5 in the YRD. With the warming and drying trend worldwide, this finding can help policymakers better consider these factors for PM2.5 prediction. Moreover, the effect of interference from humans on ecosystems will increase again after COVID-19, leading to a rise in PM2.5 concentration. The strong explanatory power of comprehensive ecological indicators for the distribution of PM2.5 will be a crucial indicator worthy of consideration by decision-making departments. [ABSTRACT FROM AUTHOR]

It is of great significance to understand the drivers of PM2.5 and fire carbon emission (FCE) and the relationship between them for the prevention, control, and policy formulation of severe PM2.5 exposure in areas where biomass burning is a major source. In this study, we considered northern Laos as the area of research, and we utilized space cluster analysis to present the spatial pattern of PM2.5 and FCE from 2003–2019. With the use of a random forest and structural equation model, we explored the relationship between PM2.5 and FCE and their drivers. The key results during the target period of the study were as follows: (1) the HH (high/high) clusters of PM2.5 concentration and FCE were very similar and distributed in the west of the study area; (2) compared with the contribution of climate variables, the contribution of FCE to PM2.5 was weak but statistically significant. The standardized coefficients were 0.5 for drought index, 0.32 for diurnal temperature range, and 0.22 for FCE; (3) climate factors are the main drivers of PM2.5 and FCE in northern Laos, among which drought and diurnal temperature range are the most influential factors. We believe that, as the heat intensifies driven by climate in tropical rainforests, this exploration and discovery can help regulators and researchers better integrate drought and diurnal temperature range into FCE and PM2.5 predictive models in order to develop effective measures to prevent and control air pollution in areas affected by biomass combustion. [ABSTRACT FROM AUTHOR]

This study investigated the effects of tanshinol (TAN) on lipopolysaccharide (LPS)-induced human keratinocytes inflammatory injury and underlying potential molecular mechanisms. Viability and apoptosis of HaCaT cells were assessed using MTT assay and Annexin V-FITC/PI staining, respectively. Quantitative reverse transcription-polymerase chain reaction was performed to measure the expression of microRNA-122 (miR-122) in HaCaT cells. Cell transfection was conducted to up-regulate the expression of miR-122. Western blotting was used to detect the protein expression levels of key factors involved in cell apoptosis, inflammatory response, c-Jun N-terminal kinase (JNK), and nuclear factor kappa B (NF-κB) pathways. We found that LPS treatment induced HaCaT cell inflammatory injury by inhibiting cell viability, promoting cell apoptosis, and enhancing the protein expression levels of cyclooxygenase 2 and inducible nitric oxide synthase. TAN treatment relieved LPS-induced HaCaT cell inflammatory injury. Moreover, TAN treatment attenuated LPS-induced activation of JNK and NF-κB pathways in HaCaT cells. Furthermore, TAN treatment alleviated LPS-induced up-regulation of miR-122. Overexpression of miR-122 reversed the effects of TAN on LPS-induced HaCaT cell inflammatory injury and activation of JNK and NF-κB pathways. In conclusion, TAN exerted anti-inflammatory and protective effects on keratinocytes injury. TAN relieved LPS-induced inflammatory injury of human HaCaT cells via down-regulating miR-122 and then inactivating JNK and NF-κB pathways. [ABSTRACT FROM AUTHOR]

Abstract Background Pressure ulcers are a kind of troublesome disease which caused by long-term pressure and subsequently lead to tissue festering necrosis because of sustained ischemia, hypoxia and malnutrition. In our study, we used hypoxia to stimulate human umbilical vein endothelial cells (HUVECs) to mimic pressure ulcers and investigated the effects of Ligustrazine (Lig) with multi-activities on HUVECs. Methods HUVECs were treated by hypoxia to induce cell injury. HUVECs were administrated with Lig and/or transfected with miR-135b inhibitor or negative control. Cell viability and cell apoptosis were detected by Cell Counting kit-8 assay and flow cytometry, respectively. The protein expression of Cyclin D1 and p53, the apoptosis-related proteins (Bcl-2, Bax, pro-/Cleaved-Caspas-3), and the JNK/SAPK and PI3K/AKT/mTOR pathways related proteins was examined by western blot. Results Hypoxia-induced injury presented by decreasing cell viability and increasing cell apoptosis. Then Lig administration enhanced cell viability and inhibited cell apoptosis. Importantly, miR-135b was upregulated by the treatment of Lig. Further studies revealed that transfection with miR-135b inhibitor led to the opposite result with decreasing cell viability and increasing cell apoptosis. In addition, Lig increased the phosphorylation of JNK, SAPK, PI3K, AKT and mTOR. Conclusion Lig promoted hypoxia-treated HUVECs cell growth as evidenced by increasing cell viability and reducing cell apoptosis. This process might be modulated by upregulation of miR-135b and subsequent activation of JNK/SAPK and PI3K/AKT/mTOR pathways. [ABSTRACT FROM AUTHOR]

Objective: To investigate the effect of fluid resuscitation and circulatory support, directed by different target mean arterial pressure (MAP), on abdominal blood flow, gastrointestinal function and inflammatory response in septic shock patients with hypertension., Methods: A prospective randomized controlled study was conducted. Hypertensive patients with septic shock admitted to the department of intensive care unit (ICU) of Liuzhou People's Hospital from January 1, 2019 to May 31, 2020 were enrolled. Patients were randomly divided into the low MAP groups (low standard group, LS group) or high MAP group (high standard group, HS group). According to the Surviving Sepsis Campaign Guidelines in 2016 and the updated guideline in 2018, all patients were given treatment of primary disease, fluid resuscitation, supportive management. The target MAP was 65-70 mmHg (1 mmHg = 0.133 kPa) in LS group, and was 75-80 mmHg in HS group. Acute gastrointestinal function injury (AGI) classification was performed on the 1st, 3rd and 7th day. The mean flow rate (Vm) and resistance index (RI) of superior mesenteric artery were evaluated using ultrasound, and the gastrointestinal function was dynamically evaluated using the modified single section ultrasonic gastric antrum method. The gastric antrum movement index (MI) and gastric empaging time (GET) were recorded. The levels of inflammatory markers in serum were detected by enzyme linked immunosorbent assay (ELISA), such as tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), procalcitonin (PCT) and vascular endothelial growth factor (VEGF). The target MAP, the days of use of vasopressors and the amount of fluid resuscitation were recorded., Results: A total of 208 hypertensive patients with septic shock were enrolled, including 109 in the LS group and 99 in the HS group. There were no significant differences in gender, age, acute physiology and chronic health evaluation II (APACHE II) score and sequential organ failure assessment (SOFA) score between the two groups when diagnosed. After treatment, there was no significant difference in AGI classification between the LS group and HS group on the 1st day. On the 3rd and 7th day, there were statistical differences between the two groups (3rd day: proportion of I, II, III, IV grades were 25.69%, 56.88%, 11.93%, 5.50% in LS group, 15.15%, 54.55%, 25.25%, 5.05% in HS group, respectively, χ 2 = 7.900, P = 0.048; 7rd day: proportion of I, II, III, IV grades were 44.96%, 49.54%, 3.67%, 1.83% in LS group, 31.31%, 52.53%, 11.11%, 5.05% in HS group, respectively, χ 2 = 8.178, P = 0.042). The Vm of superior mesenteric artery was higher and the RI was lower in the LS group than those in the HS group on day 1, 3 and 7 [Vm (cm/s): 21.72±3.02 vs. 19.50±2.83, 20.42±2.62 vs. 17.02±1.99, 26.52±2.70 vs. 22.47±4.03; RI: 0.86±0.05 vs. 0.92±0.04, 0.87±0.05 vs. 0.95±0.05, 0.81±0.03 vs. 0.85±0.03, all P < 0.01]. The MI was higher and the GET was shorter in the LS group than those in the HS group on day 3 and day 7 [MI: 3.00±0.33 vs. 2.60±0.29, 4.50±0.51 vs. 3.90±0.33; GET (minutes): 86.01±19.78 vs. 100.99±25.01, 71.00±16.37 vs. 84.98±20.18, all P < 0.01]. In addition, the levels of serum TNF-α, IL-6, PCT, VEGF were lower in the LS group than those in the HS group after 3 days of treatment [TNF-α (ng/L): 147.05±28.32 vs. 256.99±27.04, IL-6 (ng/L): 762.99±57.83 vs. 1 112.30±118.32, PCT (μg/L): 37.00±5.58 vs. 56.00±12.36, VEGF (ng/L): 123.00±19.78 vs. 167.01±21.55, all P < 0.05]. The target MAP was maintained at (68.02±4.71) mmHg in LS group, and (79.04±3.04) mmHg in HS group. The difference between the two groups was statistically significant (P < 0.01). Compared with the HS group, the days of using vasopressors was shorter in LS group (days: 3.50±1.27 vs. 4.55±1.47), and the amountof fluid was reduced significantly (mL: 1 602.29±275.49 vs. 2 000.30±272.59, both P < 0.01)., Conclusions: Maintaining a low target mean arterial pressure (65-70 mmHg) in hypertensive patients with septic shock can improve blood supply of superior mesenteric artery, protect the gastrointestinal function, reduce the level of inflammatory factors, and diminish the duration of using vasopressors and the amount of fluid.