Sustained Oxidative Stress Causes Late Acute Renal Failure via Duplex Regulation on p38 MAPK and Akt Phosphorylation in Severely Burned Rats

Background

Clinical evidence indicates that late acute renal failure (ARF) predicts high mortality in severely burned patients but the pathophysiology of late ARF remains undefined. This study was designed to test the hypothesis that sustained reactive oxygen species (ROS) induced late ARF in a severely burned rat model and to investigate the signaling mechanisms involved.

Materials and Methods

Rats were exposed to 100°C bath for 15 s to induce severe burn injury (40% of total body surface area). Renal function, ROS generation, tubular necrosis and apoptosis, and phosphorylation of MAPK and Akt were measured during 72 hours after burn.

Results

Renal function as assessed by serum creatinine and blood urea nitrogen deteriorated significantly at 3 h after burn, alleviated at 6 h but worsened at 48 h and 72 h, indicating a late ARF was induced. Apoptotic cells and cleavage caspase-3 in the kidney went up slowly and turned into significant at 48 h and 72 h. Tubular cell ROS production shot up at 6 h and continuously rose during the 72-h experiment. Scavenging ROS with tempol markedly attenuated tubular apoptosis and renal dysfunction at 72 h after burn. Interestingly, renal p38 MAPK phosphorylation elevated in a time dependent manner whereas Akt phosphorylation increased during the first 24 h but decreased at 48 h after burn. The p38 MAPK specific inhibitor SB203580 alleviated whereas Akt inhibitor exacerbated burn-induced tubular apoptosis and renal dysfunction. Furthermore, tempol treatment exerted a duplex regulation through inhibiting p38 MAPK phosphorylation but further increasing Akt phosphorylation at 72 h postburn.

Conclusions

These results demonstrate that sustained renal ROS overproduction induces continuous tubular cell apoptosis and thus a late ARF at 72 h after burn in severely burned rats, which may result from ROS-mediated activation of p38 MAPK but a late inhibition of Akt phosphorylation.     

ABNORMAL SHOOT 6 interacts with KATANIN 1 and SHADE AVOIDANCE 4 to promote cortical microtubule severing and ordering in Arabidopsis

Plant interphase cortical microtubules (cMTs) mediate anisotropic cell expansion in response to environmental and developmental cues. In Arabidopsis thaliana, KATANIN 1 (KTN1), the p60 catalytic subunit of the conserved MT‐severing enzyme katanin, is essential for cMT ordering and anisotropic cell expansion. However, the regulation of KTN1‐mediated cMT severing and ordering remains unclear. In this work, we report that the Arabidopsis IQ67 DOMAIN (IQD) family gene ABNORMAL SHOOT 6 (ABS6) encodes a MT‐associated protein. Overexpression of ABS6 leads to elongated cotyledons, directional pavement cell expansion, and highly ordered transverse cMT arrays. Genetic suppressor analysis revealed that ABS6‐mediated cMT ordering is dependent on KTN1 and SHADE AVOIDANCE 4 (SAV4). Live imaging of cMT dynamics showed that both ABS6 and SAV4 function as positive regulators of cMT severing. Furthermore, ABS6 directly interacts with KTN1 and SAV4 and promotes their recruitment to the cMTs. Finally, analysis of loss‐of‐function mutant combinations showed that ABS6, SAV4, and KTN1 work together to ensure the robust ethylene response in the apical hook of dark‐grown seedlings. Together, our findings establish ABS6 and SAV4 as positive regulators of cMT severing and ordering, and highlight the role of cMT dynamics in fine‐tuning differential growth in plants.     

C-reactive protein can influence the proliferation, apoptosis, and monocyte chemotactic protein-1 production of human umbilical vein endothelial cells

C-reactive protein (CRP) has been shown to be closely associated with coronary heart disease. The serum CRP concentrations of chronic periodontitis (CP) patients were increased due to periodontal inflammation. CRP may be a potential key mediator associating CP with coronary heart disease. This study aimed to investigate the effects of CRP on human endothelial cells in vitro. CRP ranging from 0 to 10 μg/mL was adopted to imitate the chronic inflammatory conditions of periodontitis. The influences of CRP on proliferation, apoptosis, and monocyte chemotactic protein-1 (MCP-1) production of human umbilical vein endothelial cells (HUVECs) were studied through 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, flow cytometry, and enzyme-linked immunosorbent assay analysis, respectively. Compared to the blank control, 2.5 and 5.0 μg/mL CRP significantly suppressed cell proliferation by 6.9% and increased apoptosis by 10.2% and 14.6%, respectively (p<0.05). Concentrations of 7.5 and 10.0 μg/mL CRP also induced 2.3% HUVEC proliferation suppression (p>0.05) and significantly increased apoptosis ratio compared to that of the blank control. CRP could promote MCP-1 production of HUVECs in a concentration-dependent manner. The MCP-1 production of 10.0 μg/mL CRP group was about 15.3% higher than that of the control group. It is concluded that low concentrations of CRP, which appears in CP, inhibits cell proliferation, promotes cell apoptosis, and increases MCP-1 production in endothelium, which may initiate self-repairing function of vascular endothelium following vascular injury process.     

Modified conditioning regimen with chidamide and high-dose rituximab for triple-hit lymphoma

Triple-hit lymphoma (THL), which is classified into high-grade B-cell lymphoma with rearrangements of MYC, BCL2 and BCL6, presents aggressive biological behaviour. High-dose chemotherapy followed by autologous hematopoietic stem cell transplantation (auto-HSCT) is considered to be one of the recommended treatment options. Here, we reported 3 THL patients received carmustine, etoposide, cytarabine and cyclophosphamide (BEAC) combined with chidamide and high-dose rituximab conditioning regimen and found that this conditioning showed good efficacy and tolerance without increase of adverse events.     

Three-dimensional crystallization of the Escherichia coli glycerol-3-phosphate transporter: a member of the major facilitator superfamily

Here we report the successful three-dimensional crystallization of GlpT, the glycerol-3-phosphate transporter from Escherichia coli inner membrane. GlpT possesses 12 transmembrane alpha-helices and is a member of the major facilitator superfamily. It mediates the exchange of glycerol-3-phosphate for inorganic phosphate across the membrane. Approximately 20 phospholipid molecules per protein, identified as negatively charged phosphatidylethanolamine, phosphatidylglycerol, and cardiolipin, were required for the monodispersity of purified GlpT. Analytical size-exclusion chromatography proved to be efficient in identifying detergents for GlpT monodispersity. Nine such detergents were later used for GlpT crystallization. Screening for crystal nucleation was carried out with a variety of polyethylene glycols as the precipitant over a wide pH range. Subsequent identification of a rigid protein core by limited proteolysis and mass spectroscopy resulted in better-ordered crystals. These crystals exhibited order to 3.7 A resolution in two dimensions. However, the stacking in the third dimension was partially disordered. This stacking problem was overcome by using a detergent mixture and manipulating the ionic interactions in the crystallization solution. The resulting GlpT crystals diffracted isotropically to 3.3 A resolution and were suitable for structure determination by X-ray crystallography.     

The trypanosomatid signal recognition particle consists of two RNA molecules,a 7SL RNA homologue and a novel tRNA-like molecule

Trypanosomatids are ancient eukaryotic parasites affecting humans and livestock. Here we report that the trypanosomatid signal recognition particle (SRP), unlike all other known SRPs in nature, contains, in addition to the 7SL RNA homologue, a short RNA molecule, termed sRNA-85. Using conventional chromatography, we discovered a small RNA molecule of 85 nucleotides co-migrating with the Leptomonas collosoma 7SL RNA. This RNA molecule was isolated, sequenced, and used to clone the corresponding gene. sRNA-85 was identified as a tRNA-like molecule that deviates from the canonical tRNA structure. The co-existence of these RNAs in a single complex was confirmed by affinity selection using an antisense oligonucleotide to sRNA-85. The two RNA molecules exist in a particle of approximately 14 S that binds transiently to ribosomes. Mutations were introduced in sRNA-85 that disrupted its putative potential to interact with 7SL RNA by base pairing; such mutants were unable to bind to 7SL RNA and to ribosomes and were aberrantly distributed within the cell. We postulate that sRNA-85 may functionally replace the truncated Alu domain of 7SL RNA. The discovery of sRNA-85 raises the intriguing possibility that sRNA-85 functional homologues may exist in other lower eukaryotes and eubacteria that lack the Alu domain.     

小兴安岭天然针阔混交林主要树种空间格局及其关联性

在小兴安岭天然针阔混交林1.1 hm~2的固定样地内,本文调查和统计了其物种组成和林分径级结构。运用空间点格局分析方法中的O-ring函数,对种群的空间分布格局及其关联性进行分析。结果表明:样地内共有乔木树种15种,重要值排在前四位的依次为红皮云杉(Picea koraiensis)、枫桦(Betula costata)、春榆(Ulmus davidiana)和色木槭(Acer mono),红皮云杉和枫桦属于样地内的优势种,重要值分别为15.81%和11.10%。林下更新状态良好,枫桦的径级结构有呈正态分布的趋势,其余三种均呈现倒"J"形。O-ring函数结果证实,四个主要树种的种群空间分布格局相似,均在0—5 m小尺度上呈聚集分布,随着尺度的增大,逐渐变为随机分布;红皮云杉与其他三个主要种群之间在较大尺度上均呈现显著正相关或无相关,在小尺度上仅与枫桦呈极显著正相关;色木槭在较小尺度上与其他三个种群呈弱负相关性,随着尺度的增大,逐渐变为无相关性。     

Proteomic Analysis of Silk Viability in Maize Inbred Lines and Their Corresponding Hybrids

A long period of silk viability is critical for a good seed setting rate in maize (Zea mays L.), especially for inbred lines and hybrids with a long interval between anthesis and silking. To explore the molecular mechanism of silk viability and its heterosis, three inbred lines with different silk viability characteristics (Xun928, Lx9801, and Zong3) and their two hybrids (Xun928×Zong3 and Lx9801×Zong3) were analyzed at different developmental stages by a proteomic method. The differentially accumulated proteins were identified by mass spectrometry and classified into metabolism, protein biosynthesis and folding, signal transduction and hormone homeostasis, stress and defense responses, and cellular processes. Proteins involved in nutrient (methionine) and energy (ATP) supply, which support the pollen tube growth in the silk, were important for silk viability and its heterosis. The additive and dominant effects at a single locus, as well as complex epistatic interactions at two or more loci in metabolic pathways, were the primary contributors for mid-parent heterosis of silk viability. Additionally, the proteins involved in the metabolism of anthocyanins, which indirectly negatively regulate local hormone accumulation, were also important for the mid-parent heterosis of silk viability. These results also might imply the developmental dependence of heterosis, because many of the differentially accumulated proteins made distinct contributions to the heterosis of silk viability at specific developmental stages.     

Association of Hemostatic Markers with Atrial Fibrillation: A Meta-Analysis and Meta-Regression

Background

There is growing evidence that indicates the presence of a prothrombotic state in atrial fibrillation (AF). However, the role of hemostatic markers in AF remains inconclusive.

Methods

We conducted a meta-analysis of observational studies to evaluate the association between hemostatic markers and AF. A meta-regression was performed to explore potential sources of heterogeneity.

Results

A total of 59 studies met our inclusion criteria for the meta-analysis. For platelet activation, increased circulating platelet factor-4, β-thromboglobulin (BTG) and P-selectin were significantly higher in AF cases compared with controls (standardized mean difference [SMD][95% confidence interval (CI)]: 1.72[0.96–2.49], 1.61[1.03–2.19] and 0.50[0.23–0.77], respectively). For coagulation activation, increased levels of plasma D-dimer, fibrinogen, thrombin-antithrombin, prothrombin fragment 1+2, and antithrombin-III were significantly associated with AF (SMD[95% CI]: 1.82[1.38–2.26], 0.72[0.55–0.89], 0.42[0.13–0.72], 1.00 [0.00–1.99] and 1.38[0.16–2.60], respectively). For fibrinolytic function, tissue-type plasminogen activator and plasminogen activator inhibitor-1 were significantly increased in AF cases compared with controls (SMD[95% CI]: 0.86[0.04–1.67] and 0.87[0.28–1.47], respectively) but the associations became nonsignificant after performing subgroup analysis by anticoagulants treatment status. For endothelial function, increased von Willebrand factor was significantly associated with AF (SMD, 0.79; 95% CI, 0.60–0.99); however, no association was observed for soluble thrombomodulin (SMD, 0.60; 95% CI, -0.13–1.33).

Conclusions

Increased circulating hemostatic factors (PF-4, BTG, P-selectin, D-dimer, fibrinogen, TAT, F1+2, AT- III, and vWf) are significantly associated with AF. Future research is necessary to elucidate the precise mechanism of the prothrombotic state and how hemostatic markers promote thromboembolism in AF.