Risk assessment and pathogen profile of surgical site infections in traumatic brain injury patients undergoing emergency craniotomy: A retrospective study.

Emergency craniotomy in patients with traumatic brain injury poses a significant risk for surgical site infections (SSIs). Understanding the risk factors and pathogenic characteristics of SSIs in this context is crucial for improving outcomes. This comprehensive retrospective analysis spanned from February 2020 to February 2023 at our institution. We included 25 patients with SSIs post-emergency craniotomy and a control group of 50 patients without SSIs. Data on various potential risk factors were collected, including demographic information, preoperative conditions, and intraoperative details. The BACT/ALERT3D Automated Bacterial Culture and Detection System was utilized for rapid bacterial pathogen identification. Statistical analyses included univariate and multivariate logistic regression to identify significant risk factors for SSIs. The study identified Klebsiella pneumoniae, Escherichia coli, and Staphylococcus aureus as the most prevalent pathogens in SSIs. Significant risk factors for SSIs included the lack of preoperative antibiotic use, postoperative drainage tube placement, diabetes mellitus, and the incorporation of invasive procedures, all of which showed a significant association with SSIs in the univariate analysis. The multivariate analysis further highlighted the protective effect of preoperative antibiotics and the increased risks associated with anaemia, diabetes mellitus, postoperative drainage tube placement, and the incorporation of invasive procedures. Our research underscores the critical role of factors like insufficient preoperative antibiotics, postoperative drainage, invasive techniques, anaemia, and diabetes mellitus in elevating the risk of surgical site infections in traumatic brain injury patients undergoing emergency craniotomy. Enhanced focus on these areas is essential for improving surgical outcomes.

PtomtAPX is an autonomous lignification peroxidase during the earliest stage of secondary wall formation in Populus tomentosa Carr.

At present, a cooperative process hypothesis is used to explain the supply of enzyme (class III peroxidases and/or laccases) and substrates during lignin polymerization. However, it remains elusive how xylem cells meet the needs of early lignin rapid polymerization during secondary cell wall formation. Here we provide evidence that a mitochondrial ascorbate peroxidase (PtomtAPX) is responsible for autonomous lignification during the earliest stage of secondary cell wall formation in Populus tomentosa. PtomtAPX was relocated to cell walls undergoing programmed cell death and catalysed lignin polymerization in vitro. Aberrant phenotypes were caused by altered PtomtAPX expression levels in P. tomentosa. These results reveal that PtomtAPX is crucial for catalysing lignin polymerization during the early stages of secondary cell wall formation and xylem development, and describe how xylem cells provide autonomous enzymes needed for lignin polymerization during rapid formation of the secondary cell wall by coupling with the programmed cell death process.

MYB2 Is Important for Tapetal PCD and Pollen Development by Directly Activating Protease Expression in Arabidopsis.

Tapetal programmed cell death (PCD) is a complex biological process that plays an important role in pollen formation and reproduction. Here, we identified the MYB2 transcription factor expressed in the tapetum from stage 5 to stage 11 that was essential for tapetal PCD and pollen development in Arabidopsis thaliana. Downregulation of MYB2 retarded tapetal degeneration, produced defective pollen, and decreased pollen vitality. EMSA and transcriptional activation analysis revealed that MYB2 acted as an upstream activator and directly regulated expression of the proteases CEP1 and ßVPE. The expression of these proteases was lower in the buds of the myb2 mutant. Overexpression of either/both CEP1 or/and ßVPE proteases partially recover pollen vitality in the myb2 background. Taken together, our results revealed that MYB2 regulates tapetal PCD and pollen development by directly activating expression of the proteases CEP1 and ßVPE. Thus, a transcription factor/proteases regulatory and activated cascade was established for tapetal PCD during another development in Arabidopsis thaliana. Highlight: MYB2 is involved in tapetal PCD and pollen development by directly regulating expression of the protease CEP1 and ßVPE and establishes a transcription factor/proteases regulatory and activated cascade.

How Cysteine Protease Gene PtCP5 Affects Seed Germination by Mobilizing Storage Proteins in Populus trichocarpa.

In higher plants, seed storage proteins are deposited in protein storage vacuoles (PSVs) and degraded by protease, especially cysteine proteases, as a source of nitrogen for seed germination. In this study, a cathepsin B-like cysteine protease PtCP5, which is important for seed germination and pollen development, was first cloned in Populus trichocarpa. The GUS staining of the ProPtCP5-GUS reporter line showed that PtCP5 is expressed in the roots, stems, leaves, flowers, siliques and seeds of Arabidopsis. We reveal that PtCP5 is present in plasma membrane and co-localizes with the plasma membrane marker REM1.3. Both seed germination and early seedling development are slower in OX-PtCP5 transgenic Arabidopsis when compared with the wild-type. Further analysis revealed that, when stained with toluidine blue, the observed storage protein accumulation was lower in OX-PtCP5 than in the wild-type. Our results also show that the number of abnormal pollen grains is higher and the germination rate of pollen is lower in OX-PtCP5 than in the wild-type. These results indicate that PtCP5 is an important factor in mobilizing storage proteins and that the proper expression of PtCP5 is necessary for both pollen and seed maturation and germination. This study sheds further light on the biological functions of cysteine proteases and provides further reference for seed development research on woody plants.

Integrated Transcriptomic and Proteomic Analysis in the Roadmap of the Xylem Development Stage in Populus tomentosa.

Xylem development plays an important role in the wood formation of plants. In this study, we found that xylem development was a rapid thickening process characterized by initially rapid increases in the number of tracheary elements and fiber cells and the thickness of the secondary walls that later plateaued. Transcriptome analysis showed that the xylan and lignin biosynthetic pathways, which are involved in the early rapid thickening of the xylem, were mainly upregulated in the second month. The expression of a total of 124 transcription factors (TFs), including 28 NAC TFs and 31 MYB TFs, peaked in 2- and 3-month-old plants compared with 1-month-old plants. Based on previous studies and the key cis-acting elements secondary wall NAC-binding elements, secondary wall MYB-responsive elements, W-box and TGTG[T/G/C], 10 TFs related to xylem development, 50 TFs with unknown function, 98 cell wall biosynthetic genes, and 47 programmed cell death (PCD) genes were used to construct a four-layer transcriptional regulatory network (TRN) with poplar NAC domain TFs to characterize the transcriptional regulation of cell wall biosynthesis and PCD in Populus tomentosa. The proteome revealed that post-transcriptional modification may be widely involved in lignification development. Overall, our results revealed that xylem development is a rapid thickening process in P. tomentosa, and expression patterns varied temporally from cell division to cell death.

PtrLAC16 plays a key role in catalyzing lignin polymerization in the xylem cell wall of Populus.

Plant laccases have been proposed to participate in lignin biosynthesis. However, there is no direct evidence that individual laccases in Populus can polymerize lignin monomers and alter cell wall structure. Here, a Populus laccase, PtrLAC16, was expressed and purified in a eukaryotic system. Enzymatic analysis of PtrLAC16 showed that it could polymerize lignin monomers in vitro. PtrLAC16 preferred sinapyl alcohol, and this preference is associated with an altered S/G ratio in transgenic Populus lines. PtrLAC16 was localized exclusively in the cell walls of stem vascular tissue, and a reduction in PtrLAC16 expression led to a significant decrease in lignin content and altered cell wall structure. There was a direct correlation between the inhibition of PtrLAC16 expression and structural changes in the stem cell wall of Populus. This study provides direct evidence that PtrLAC16 plays a key role in the polymerization of lignin monomers, especially for sinapyl lignin, and affects the formation of xylem cell walls in Populus.

Chloroplast thylakoid ascorbate peroxidase PtotAPX plays a key role in chloroplast development by decreasing hydrogen peroxide in Populus tomentosa.

Chloroplast development is a complex process that is critical to the growth and development of plants. However, the detailed mechanism of chloroplast development in woody plants remains unclear. In this study, we showed that chloroplasts with elaborate thylakoids could develop from proplastids in the cells of calli derived from leaf tissues of Populus tomentosa upon exposure to light. Chloroplast development was confirmed at the molecular and cellular levels. Transcriptome analysis revealed that genes related to photoreceptors and photosynthesis were significantly up-regulated during chloroplast development in a time-dependent manner. In light-induced chloroplast development, a key process was the removal of hydrogen peroxide, in which thylakoid-localized PtotAPX played a major role; light-induced chloroplast development was enhanced in PtotAPX-overexpressing transgenic P. tomentosa callus with lower levels of hydrogen peroxide, but was suppressed in PtotAPX antisense transgenic callus with higher levels of hydrogen peroxide. Moreover, the suppression of light-induced chloroplast development in PtotAPX antisense transgenic callus was relieved by the exogenous reactive oxygen species scavenging agent N,N'-dimethylthiourea (DMTU). Based on these results, we propose that PtotAPX-mediated removal of reactive oxygen species plays a key role in chloroplast development from proplastids upon exposure to light in P. tomentosa.

Histone Deacetylase HDT1 is Involved in Stem Vascular Development in Arabidopsis.

Histone acetylation and deacetylation play essential roles in eukaryotic gene regulation. HD2 (HD-tuins) proteins were previously identified as plant-specific histone deacetylases. In this study, we investigated the function of the HDT1 gene in the formation of stem vascular tissue in Arabidopsis thaliana. The height and thickness of the inflorescence stems in the hdt1 mutant was lower than that of wild-type plants. Paraffin sections showed that the cell number increased compared to the wild type, while transmission electron microscopy showed that the size of individual tracheary elements and fiber cells significantly decreased in the hdt1 mutant. In addition, the cell wall thickness of tracheary elements and fiber cells increased. We also found that the lignin content in the stem of the hdt1 mutants increased compared to that of the wild type. Transcriptomic data revealed that the expression levels of many biosynthetic genes related to secondary wall components, including cellulose, lignin biosynthesis, and hormone-related genes, were altered, which may lead to the altered phenotype in vascular tissue of the hdt1 mutant. These results suggested that HDT1 is involved in development of the vascular tissue of the stem by affecting cell proliferation and differentiation.