[Effects of Biochar Application on Soil Organic Carbon Component in Eucalyptus Plantations After Five Years in Northern Guangxi].

To investigate the effects of biochar(BC) addition on soil organic carbon(SOC) contents and its fractions under different biochar applications, Eucalyptus waste twigs in Northern Guangxi were used to produce BC at 500℃. Additionally, we sought to clarify and define the carbon sequestration potential of soil and provide a basis for the preparation of biochar from Eucalyptus forest wastes and soil improvement. In a long-term positioning test of biochar application from 1997, six different treatments were selected:0(CK), 0.5%(T1), 1%(T2), 2%(T3), 4%(T4), and 6%(T5). The contents of SOC, light fraction organic carbon(LFOC), heavy fraction organic carbon(HFOC), easily oxidized organic carbon(EOC), dissolved organic carbon(DOC), particulate organic carbon(POC), microbial biomass carbon(MBC), and carbon stock(CS) following the different treatments were measured. The results showed that:① compared to that in the control, biochar application induced an increase in each soil organic carbon fraction with increasing application rate and reached a maximum under the T4 or T5 treatments; with the increase in biochar application, the contents of SOC, DOC, EOC, POC, MBC, and CS increased significantly by 101.62%, 67.46%, 143.03%, 164.78%, 110.88%, and 41.73%, respectively. ② The contents of LFOC and HFOC in the 0-10, 10-20, and 20-30 cm soil layers increased significantly by 41.41%-140.63%, 9.26%-87.04%, and -19.54%-106.90% and 15.32%-78.99%, 15.72%-75.25%, and 89.49%-148.64%, respectively, with the increase in biochar application. The average contents of LFOC and HFOC in the 0-30 cm soil layer also increased gradually. The soil carbon pool of the Eucalyptus forest was dominated by a relatively stable heavy fraction organic carbon. ③ The contents of carbon stock, soil organic carbon, and its fractions decreased with the increase in soil depth. In conclusion, the application of forestry waste biochar for five years could significantly increase the content of SOC and its components, thereby increasing soil organic carbon activity. Therefore, increasing the amount of biochar was an effective measure to enhance the carbon storage, soil stable carbon pool, and soil quality of the Eucalyptus plantation field. This study provides a reference for the resource utilization of forestry waste and improvements in soil fertility of Eucalyptus plantations.

[Effects of Biochar Application on Soil Organic Nitrogen Component and Active Nitrogen in Eucalyptus Plantations After Five Years in Northern Guangxi].

The objective of this study was to research the characteristics of fractions of organic nitrogen and active nitrogen and their relationship under different biochar applications and to provide a basis for the preparation and practical application of biochar from Eucalyptus forest wastes. In a long-term positioning test of biochar application from 2017, six different treatments were selected:0(CK), 0.5%(T1), 1%(T2), 2%(T3), 4%(T4), and 6%(T5). The contents of soil organic nitrogen components, total nitrogen(TN), dissolved organic nitrogen(DON), and microbial biomass nitrogen(MBN) following the different treatments were measured. The results showed that:① compared with that of the control, with the increase in biochar application, the contents of soil TN, acidolysis of total organic nitrogen(AHON), ammonia nitrogen(AN), amino acid nitrogen(AAN), MBN, DON, and nitrogen storage(NS) increased significantly by 45.48%-156.32%, 44.31%-171.31%, 38.06%-223.37%, 39.42%-163.32%, 36.72%-109%, 23.27%-113.51%, and 29.45%-62.37%, respectively. The contents of soil hydrolyzable unknown nitrogen(HUN) and non-hydrolyzable nitrogen(NHN) also increased significantly by 88.41%-158.71% and 50.24%-139.01%, respectively. The contents of soil amino sugar nitrogen(ASN) decreased by 7.72%-32.73%. The contents of different forms of organic nitrogen fractions in all treatments displayed an order of AN > AAN > NHN > HUN > ASN. Compared with the no biochar treatment, each biochar treatment increased the contents and proportion of AHON in the TN. ② With the exception of HUN, the contents of other soil organic nitrogen components and active nitrogen content decreased with the increase in soil depth. ③ There were significantly positive correlations between TN, MBN, and DON and AHON, NHN, and NS contents. The principal component analysis showed that bulk density and ASN and TN and HUN, AAN, DON, and AHON were closely related, respectively. In conclusion, the application of forestry waste biochar for five years could significantly increase the content of soil organic nitrogen component and active nitrogen, thereby improving the capacity of the soil to supply nitrogen. AHON, AN, and AAN were the main factors contributing to soil active nitrogen content.

Roxadustat regulates iron metabolism in dialysis-dependent and non-dialysis-dependent chronic kidney disease patients: A meta-analysis.

BACKGROUND/PURPOSE: The effect of roxadustat on iron homeostasis in patients with chronic kidney disease (CKD) is unclear. This study aimed to evaluate the efficacy of roxadustat for the treatment of iron metabolism disorders in dialysis-dependent (DD) and non-dialysis-dependent (NDD) CKD patients. METHODS: We searched the PubMed, Embase, China National Knowledge Internet and Web of Science databases for randomized controlled trials (RCTs). The primary outcomes were changes in serum iron, total iron binding capacity (TIBC), transferrin saturation (TSAT), ferritin, transferrin, and hepcidin. The secondary outcomes included the changes in hemoglobin (Hb) and the incidences of adverse events (AEs) and severe adverse events (SAEs). RESULTS: Twelve RCTs comprising 4976 participants were included. Compared to the control group, increases in the serum iron (SMD = 0.21, 95% CI: 0.15 to 0.27, P < 0.00001), TIBC (SMD = 1.02, 95% CI: 0.82 to 1.22, P < 0.00001) and transferrin levels (WMD = 0.55, 95% CI: 0.41 to 0.69, P < 0.00001) were found in the roxadustat group. Compared to the control group, decreases in the ferritin levels (WMD = -37.82, 95% CI: -59.89 to -15.74, P = 0.0008) and hepcidin levels (WMD = -24.04, 95% CI: -36.28 to -11.79, P = 0.0001) were observed in the roxadustat group. The meta-analysis showed that roxadustat significantly increases Hb levels (WMD = 0.77, 95% CI: 0.42 to 1.12, P < 0.0001). The incidences of AEs and SAEs in the roxadustat group was significantly higher than that in the control group (RR = 1.03, 95% CI: 1.00 to 1.07, P = 0.04; RR = 1.08, 95% CI: 1.00 to 1.15, P = 0.04). CONCLUSION: Our findings suggest that roxadustat could effectively improve iron metabolism in patients with CKD.

Hypoxia-inducible factor protects against acute kidney injury via the Wnt/ß-catenin signaling pathway.

Promoting adaptive repair in acute kidney injury (AKI) is an effective strategy to prevent the progression from AKI to chronic kidney disease. However, the mechanisms involved in renal repair after AKI remain unclear. In this study, we investigated the role of hypoxia-inducible factor (HIF), an important regulator of ischemic and hypoxic injury, in AKI during the repair phase. We established mouse models of ischemia-reperfusion injury-induced AKI with adaptive repair or maladaptive repair. We found that after injury, activation of HIF in the adaptive repair group was rapid, whereas in the maladaptive repair group HIF activation was relatively delayed, and its expression was significantly lower than that in the adaptive repair group during the early repair phase. To further investigate the mechanism of HIF, we regulated the expression of HIF-1α and HIF-2α in HK-2 cells and EA.hy926 cells, respectively. Silencing HIF expression reduced proliferation and increased apoptosis in cells injured by hypoxia/reoxygenation. Self-healing ability was further reduced due to the downregulation of HIF. Moreover, HIF overexpression had the opposite effect. HIF increased the expression of ß-catenin and its downstream target genes. Activation of Wnt/ß-catenin by the small-molecule activator SKL2001 mitigated the damaging effect of HIF knockdown, whereas blockade of ß-catenin with the inhibitor IWR-1-endo reduced the protective effects of HIF. In conclusion, HIF, which is highly expressed in the early stage after AKI, promotes renal repair by interacting with the Wnt/ß-catenin signaling pathway.NEW & NOTEWORTHY We investigated the role of hypoxia-inducible factor (HIF) in acute kidney injury in vivo and in vitro. Expression of HIF in the adaptive repair group was more rapid and sufficient than that in the maladaptive repair group during the early repair phase. HK-2 and EA.hy926 cells treated with hypoxia/reoxygenation were used to elucidate the cross talk between HIF and the Wnt/ß-catenin signaling pathway by which HIF played a renoprotective role in acute kidney injury.

Roxadustat treatment for anemia in peritoneal dialysis patients: A randomized controlled trial.

BACKGROUND/PURPOSE: Roxadustat, a first-in-class hypoxia-inducible factor prolyl hydroxylase inhibitor, promotes erythropoiesis and regulates iron metabolism. This study investigated the efficacy and safety of roxadustat in Chinese patients with anemia on peritoneal dialysis (PD). METHODS: One hundred and twenty-nine patients were randomized and treated with roxadustat (n = 86) or erythropoiesis-stimulating agents (ESAs) (n = 43) for 24 weeks. The primary end points were the mean hemoglobin (Hb) level at week 24, the change in average Hb levels from baseline to week 24, and the cumulative response rate throughout the treatment period. The secondary end points included changes in hepcidin and iron indices and serum lipid levels. Subgroup analysis examined the effect of inflammatory status on the efficacy of Hb. Safety was assessed as the occurrence of emergent adverse events after treatment. RESULTS: The mean average Hb levels at week 24 and average change in Hb levels from baseline to week 24 were 11.5 g/dL and 2.5 g/dL in the roxadustat group and 11.2 g/dL and 2.2 g/dL in the ESAs group, respectively. The cumulative response rate was 96% in the roxadustat group and 92% in the ESAs group at week 24. Roxadustat decreased hepcidin levels and increased total iron-binding capacity. The decreases in total cholesterol and low-density lipoprotein cholesterol were greater with roxadustat than with ESAs. Roxadustat-induced Hb increases were independent of baseline C-reactive protein levels. Common adverse events included hyperkalemia, hypertension, and insomnia. CONCLUSION: Roxadustat effectively corrected and maintained target Hb levels in Chinese PD patients. This trial was registered in the Chinese Clinical Trial Register (ChiCTR2000035054).

Bioinformatic Analysis Combined With Experimental Validation Reveals Novel Hub Genes and Pathways Associated With Focal Segmental Glomerulosclerosis.

Background: Focal segmental glomerulosclerosis (FSGS) is a type of nephrotic syndrome leading to end-stage renal disease, and this study aimed to explore the hub genes and pathways associated with FSGS to identify potential diagnostic and therapeutic targets. Methods: We downloaded the microarray datasets GSE121233 and GSE129973 from the Gene Expression Omnibus (GEO) database. The datasets comprise 25 FSGS samples and 25 normal samples. The differential expression genes (DEGs) were identified using the R package "limma". Gene Ontology (GO) function and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed using the database for Annotation, Visualization and Integrated Discovery (DAVID) to identify the pathways and functional annotation of the DEGs. The protein-protein interaction (PPI) was constructed based on the Search Tool for the Retrieval of Interacting Genes (STRING) database and visualized using Cytoscape software. The hub genes of the DEGs were then evaluated using the cytoHubba plugin of Cytoscape. The expression of the hub genes was validated by quantitative real-time polymerase chain reaction (qRT-PCR) using the FSGS rat model, and receiver operating characteristic (ROC) curve analysis was performed to validate the accuracy of these hub genes. Results: A total of 45 DEGs including 18 upregulated and 27 downregulated DEGs, were identified in the two GSE datasets (GSE121233 and GSE129973). Among them, five hub genes with a high degree of connectivity were selected. From the PPI network, of the top five hub genes, FN1 was upregulated, while ALB, EGF, TTR, and KNG1 were downregulated. The qRT-PCR analysis of FSGS rats confirmed that the expression of FN1 was upregulated and that of EGF and TTR was downregulated. The ROC analysis indicated that FN1, EGF, and TTR showed considerable diagnostic efficiency for FSGS. Conclusion: Three novel FSGS-specific genes were identified through bioinformatic analysis combined with experimental validation, which may promote our understanding of the molecular underpinning of FSGS and provide potential therapeutic targets for the clinical management.

Wnt4 is a novel biomarker for the early detection of kidney tubular injury after ischemia/reperfusion injury.

Earlier intervention after acute kidney injury would promote better outcomes. Our previous study found that Wnt proteins are promptly upregulated after ischemic kidney injury. Thus, we assessed whether Wnt4 could be an early and sensitive biomarker of tubular injury. We subjected mice to bilateral ischemia/reperfusion injury (IRI). Kidney and urinary Wnt4 expression showed an early increase at 3 hours and increased further at 24 hours post-IRI and was closely correlated with histopathological alterations. Serum creatinine slightly increased at 6 hours, indicating that it was less sensitive than Wnt4 expression. These data were further confirmed by clinical study. Both kidney and urinary Wnt4 expression were significantly increased in patients diagnosed with biopsy-proven minimal change disease (MCD) with tubular injury, all of whom nevertheless had normal estimated glomerular filtration rate (eGFR) and serum creatinine. The increased Wnt4 expression also strongly correlated with histopathological alterations in these MCD patients. In conclusion, this is the first demonstration that increases in both kidney and urinary Wnt4 expression can be detected more sensitively and earlier than serum creatinine after kidney injury. In particular, urinary Wnt4 could be a potential noninvasive biomarker for the early detection of tubular injury.