Ablation of long noncoding RNA MALAT1 activates antioxidant pathway and alleviates sepsis in mice.

The metastasis-associated lung adenocarcinoma transcript1 (MALAT1) is a long noncoding RNA (lncRNA) and is known for its role in cancer development and prognosis. In this study, we report that MALAT1 plays an important role in regulating acute inflammatory responses in sepsis. In patient samples, MALAT1 expression was positively correlated with severity of sepsis. In cultured macrophages, LPS treatment significantly induced MALAT1 expression, while genetic ablation of MALAT1 greatly reduced proinflammatory cytokine levels. Furthermore, MALAT1-ablated mice had significantly increased survival rates in cecal ligation and puncture (CLP)-induced sepsis and LPS-induced endotoxemia. One novel and salient feature of MALAT1-ablated mice is greatly reduced ROS level in macrophages and other cell types and increased glutathione/oxidized glutathione (GSH/GSSG) ratio in macrophages, suggesting an increased antioxidant capacity. We showed a mechanism for MALAT1 ablation leading to enhanced antioxidant capacity is through activation of methionine cycle by epitranscriptomical regulation of methionine adenosyltransferase 2A (MAT2A). MAT2A 3'UTR can be methylated by METTL16 which was known to directly bind to MALAT1. MALAT1 ablation was found to reduce methylation in MAT2A hairpin1 and increase MAT2A protein levels. Our results suggest a MALAT1-METTL16-MAT2A interactive axis which may be targeted for treatments of sepsis.

A prospective cohort study on the clinical value of pelvic peritoneal reconstruction in laparoscopic anterior resection for middle and low rectal cancer / 中华胃肠外科杂志

Objective: To investigate the safety and efficacy of pelvic peritoneal reconstruction and its effect on anal function in laparoscopy-assisted anterior resection of low and middle rectal cancer. Methods: A prospective cohort study was conducted. Consecutive patients with low and middle rectal cancer who underwent laparoscopy-assisted transabdominal anterior resection at Naval Military Medical University Changhai Hospital from February 2020 to February 2021 were enrolled. Inclusion criteria: (1) the distance from tumor to the anal verge ≤10 cm; (2) laparoscopy-assisted transabdominal anterior resection of rectal cancer; (3) complete clinical data; (4) rectal adenocarcinoma diagnosed by postoperative pathology. Exclusion criteria: (1) emergency surgery; (2) patients with a history of anal dysfunction or anal surgery; (3) preoperative diagnosis of distant (liver, lung) metastasis; (4) intestinal obstruction; (5) conversion to open surgery for various reasons. The pelvic floor was reconstructed using SXMD1B405 (Stratafix helical PGA-PCL, Ethicon). The first needle was sutured from the left anterior wall of the neorectum to the right. Insertion of the needle was continued to suture the root of the sigmoid mesentery while the Hemo-lok was used to fix the suture. The second needle was started from the beginning of the first needle, after 3-4 needles, a drainage tube was inserted through the left lower abdominal trocar to the presacral space. Then, the left peritoneal incision of the descending colon was sutured, after which Hemo-lok fixation was performed. The operative time, perioperative complications, postoperative Wexner anal function score and low anterior resection syndrome (LARS) score were compared between the study group and the control group. Three to six months after the operation, pelvic MRI was performed to observe and compare the pelvic floor anatomical structure of the two groups. Results: A total of 230 patients were enrolled, including 58 who underwent pelvic floor peritoneum reconstruction as the study group and 172 who did not undergo pelvic floor peritoneum reconstruction as the control group. There were no significant differences in general data between the two groups (all P>0.05). The operation time of the study group was longer than that of control group [(177.5±33.0) minutes vs. (148.7±45.5) minutes, P<0.001]. There was no significant difference in the incidence of perioperative complications (including anastomotic leakage, anastomotic bleeding, postoperative pneumonia, urinary tract infection, deep vein thrombosis, and intestinal obstruction) between the two groups (all P>0.05). Eight cases had anastomotic leakage, of whom 2 cases (3.4%) in the study group were discharged after conservative treatment, 5 cases (2.9%) of other 6 cases (3.5%) in the control group were discharged after the secondary surgical treatment. The Wexner score and LARS score were 3.1±2.8 and 23.0 (16.0-28.0) in the study group, which were lower than those in the control group [4.7±3.4 and 27.0 (18.0-32.0)], and the differences were statistically significant (t=-3.018, P=0.003 and Z=-2.257, P=0.024). Severe LARS was 16.5% (7/45) in study group and 35.5% (50/141) in control group, and the difference was no significant differences (Z=4.373, P=0.373). Pelvic MRI examination 3 to 6 months after surgery showed that the incidence of intestinal accumulation in the pelvic floor was 9.1% (3/33) in study group and 46.4% (64/138) in control group (χ(2)=15.537, P<0.001). Conclusion: Pelvic peritoneal reconstruction using stratafix in laparoscopic anterior resection of middle and low rectal cancer is safe and feasible, which may reduce the probability of the secondary operation in patients with anastomotic leakage and significantly improve postoperative anal function.

Etiological analysis and surgical method selection of adult megacolon / 中华胃肠外科杂志

Adult megacolon is a rare disease with heterogeneneous etiology. The treatment schemes of megacolon caused by different causes are also different, but surgery is the final and the most effective method. Due to the lack of early understanding of the disease, many patients have not been clearly diagnosed as adult megacolon and have not been properly treated. This article classifies adult megacolon according to the etiology and summarizes its surgical options. For adult Hirschsprung's disease, modified Duhamel, the Jinling procedure, low anterior resection, or pull-through low anterior resection can be used. For patients with idiopathic megacolon, one-stage subtotal colorectal resection can be selected with adequate preoperative preparations. Some patients admitted to the hospital with emergency intestinal obstruction can be treated with conservative treatment or decompression under colonoscopy followed by selective surgery. For patients with aganglionosis, the procedure is subtotal colorectal resection, the same as that of idiopathic megacolon. The procedure is to remove both the dilated proximal intestine and the stenotic distal intestine, then an ileorectal anastomosis or ascending colon rectal anastomosis is performed. For toxic megacolon, colostomy can be done for mild cases, and for severe infections, subtotal colorectal resection is required. Latrogenic megacolon is mostly caused by segmental stenosis or lack of peristalsis, resulting in chronic dilatation of the proximal end and the formation of megacolon. It is necessary to choose a reasonable surgical procedure according to the specific conditions of the patient. The first choice for the treatment of acute colonic pseudo-obstruction syndrome is decompression under colonoscopy. For those with the secondary changes in the intestine, ostomy is still the most effective surgical procedure, but should be performed with caution.

Epigenetic sensitization of pregnane X receptor-regulated gene expression by dimethyl sulfoxide.

Prior exposures to chemicals/agents may alter epigenome in such a way that subsequent exposure to the same or different xenobiotic would produce different responses. Understanding the mechanism for this "priming" effect is of clinical significance in avoiding adverse drug-drug interactions. Here we reported a dramatic priming effect of dimethyl sulfoxide (DMSO) on pregnane X receptor (PXR)-mediated gene regulations and analyzed the underpinning epigenetic mechanism. We showed that DMSO (1.25-2.5 %) pretreatment has a profound effect in enhancing the expression of PXR target genes. This priming effect persisted up to 48 h. Mechanistically, DMSO pretreatment reduced H4K12 acetylation and therefore enhanced the subsequent rifampicin stimulated histone H4R3 methylation on the regulatory region of PXR target gene CYP3A4. We showed that protein arginine methyltransferase 1 (PRMT1), which methylates H4R3, was important for priming by DMSO. Inhibition of methyltransferase by the pharmacological inhibitor adenosine dialehyde (AdoX), or RNAi knockdown of PRMT1, abolished the DMSO priming effects. On the other hand, Trichostation A (TSA) pretreatment, which increases histone acetylation and therefore suppresses H4R3 methylation, also abolished the DMSO priming effects. Based on the above observation, we proposed a model of sequential order of histone methylation and acetylation on the transcription "relay".

Indication and operation skills of colonoscopy for bowel obstruction / 中国实用外科杂志

As one of the major acute abdomen in general surgery,the treatment of bowel obstruction has made great progress at present,but it is still a difficult problem for doctors to deal with.The key question is to make clear the cause of obstruction,the choice of treatment method and operation time. With the progress of technology and equipment,colonoscopy has been applied more and more to the diagnosis and treatment of intestinal obstruction from the contraindications of bowel obstruction to the present,and become an important means to judge the state of illness,guide and implement treatment. However, the emergency colonoscopy for patients with bowel obstruction has its own particularity,which is different from the selective colonoscopy.From the preparation of tract before examination,such as not taking cathartic,and trying to be as simple and effective as possible, to the colonoscopy for patients with bowel obstruction,surgeons should take different schemes and skills according to the different causes and positions of obstruction.

A Murine Pancreatic Islet Cell-based Screening for Diabetogenic Environmental Chemicals.

Exposure to certain environmental chemicals in human and animals has been found to cause cellular damage of the pancreatic ß cells which will lead to the development of type 2 diabetes mellitus (T2DM). Although the mechanisms for the chemical-induced ß cell damage were unclear and likely to be complex, one recurring finding is that these chemicals induce oxidative stress leading to the generation of excessive reactive oxygen species (ROS) which induce damage to the ß cell. To identify potential diabetogenic environmental chemicals, we isolated pancreatic islet cells from C57BL/6 mice and cultured islet cells in 96-well cell culture plates; then, the islet cells were dosed with chemicals and the ROS generation was detected by 2',7'-dichlorofluorescein (DCFH-DA) fluorescent dye. Using this method, we found that bisphenol A (BPA), Benzo[a]pyrene (BaP), and polychlorinated biphenyls (PCBs), could induce high levels of ROS, suggesting that they may potentially induce damage in islet cells. This method should be useful for screening diabetogenic xenobiotics. In addition, the cultured islet cells may also be adapted for in vitro analysis of chemical-induced toxicity in pancreatic cells.

Long noncoding RNA MALAT1 regulates generation of reactive oxygen species and the insulin responses in male mice.

The metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is a long noncoding RNA and its overexpression is associated with the development of many types of malignancy. MALAT1 null mice show no overt phenotype. However, in transcriptome analysis of MALAT1 null mice we found significant upregulation of nuclear factor-erythroid 2 p45-related factor 2 (Nrf2) regulated antioxidant genes including Nqo1 and Cat with significant reduction in reactive oxygen species (ROS) and greatly reduced ROS-generated protein carbonylation in hepatocyte and islets. We performed lncRNA pulldown assay using biotinylated antisense oligonucleotides against MALAT1 and found MALAT1 interacted with Nrf2, suggesting Nrf2 is transcriptionally regulated by MALAT1. Exposure to excessive ROS has been shown to cause insulin resistance through activation of c-Jun N-terminal kinase (JNK) which leads to inhibition of insulin receptor substrate 1 (IRS-1) and insulin-induced phosphorylation of serine/threonine kinase Akt. We found MALAT1 ablation suppressed JNK activity with concomitant insulin-induced activation of IRS-1 and phosphorylation of Akt suggesting MALAT1 regulated insulin responses. MALAT1 null mice exhibited sensitized insulin-signaling response to fast-refeeding and glucose/insulin challenges and significantly increased insulin secretion in response to glucose challenge in isolated MALAT1 null islets, suggesting an increased insulin sensitivity. In summary, we demonstrate that MALAT1 plays an important role in regulating insulin sensitivity and has the potential as a therapeutic target for the treatment of diabetes as well as other diseases caused by excessive exposure to ROS.

Pregnane X receptor regulates the AhR/Cyp1A1 pathway and protects liver cells from benzo-[α]-pyrene-induced DNA damage.

Pregnane X receptor (PXR) plays an important role in protecting cells from mutagenic DNA damages induced by endogenous and exogenous toxicants. This protective function is often attributed to the PXR-regulated metabolic detoxification. Here we report a novel potential mechanism that PXR reduces benzo-[α]-pyrene(BaP)-induced DNA damage through inhibiting the transcriptional activity of aryl hydrocarbon receptor (AhR) which plays a pivotal role in the bioactivation of BaP. We have utilized three well-characterized cell lines, i.e. Hepa1c1c7, AhR +/+; Bpr lacks AhR obligatory partner ARNT; Tao, lacks AhR, to analyze pivotal role of AhR/ARNT complex in mediating the BaP-induced DNA damages using comet assay (single-cell gel electrophoresis). We found that PXR activation could significantly inhibit BaP-induced DNA damage in the HepG2 cells as well as mouse hepatocytes. Using PXR-null and wild type mouse hepatocytes we showed that PXR activation by pregnenolone 16α-carbonitrile (PCN) significantly inhibited BaP-induced DNA damage and this protective effect was abolished in PXR-null hepatocytes. Mechanistically, PXR activation inhibited expression of AhR-target genes for CYP1A1, CYP1B1 and CYP1A2 that are required for BaP biotransformation in cultured liver cells, or in the livers of C57BL/6J mice. Using an AhR-responsive reporter assay as well as chromatin immunoprecipitation assay we found that PXR activation transcriptionally represses AhR-regulated gene expression. Furthermore, we found that PXR directly bound AhR at its DNA-binding domain, and this association may play a role in preventing of the AhR from binding to its target genes as shown in the ChIP assay. Taken together, our study has revealed a novel mechanism by which PXR protects liver cells from BaP-induced DNA damage through inhibiting the BaP biotransformation.

A cone-beam CT study on alveolar bone morphology in anterior teeth area of adult skeletal Class Ⅱ mal-occlusion subjects with different vertical skeletal types / 实用口腔医学杂志

Objective:To study the alveolar bone morphology in the anterior teeth area of the skeletal Class Ⅱ malocclusion subjects with different vertical skeletal types.Methods:64 patients with skeletal Class Ⅱ malocclusion and 15 subjects with normal occlusion were included.The alveolar bone structure of the anterior teeth were observed using CBCT.Results:The labial and lingual alveolar bone height and the alveolar bone thickness of the incisors of the patients were much lower than those of the normal controls.The height of labial and lingual alveolar bone and the alveolar bone thickness of anterior teeth in high-angle subgroup were lower than those in low-angle subgroup.Conclusion:The thickness of the anterior teeth alveolar bone of skeletal Class Ⅱ malocclusion is low,espe-cially in the high-angle group.

Construction of endothelial progenitor cells/bone marrow mesenchymal stem cells composite sheets / 中国组织工程研究

BACKGROUND:Many studies have showed that enough blood supply is an essential condition of bone repair and regeneration. OBJECTIVE:To construct the endothelial progenitor cells/bone marrow mesenchymal stem cells (EPCs/BMSCs) composite sheet. METHODS:After isolation and culture, EPCs and BMSCs were co-cultured directly to form EPCs/BMSCs sheet by cellsheet-inducing medium. After 10 days of induction, the sheet was investigated by gross observation, inverted microscope and hematoxylin-eosin staining. The distribution and communication of EPCs and BMSCs during the process of cellsheet induction were observed after the fluorescence labeling separately. Alkaline phosphatase assay and alizarin red staining were applied to examine the ability of osteogenic differentiation of EPCs/BMSCs sheet. RESULTS AND CONCLUSION:EPCs/BMSCs sheet was harvested after 10-day induction. Cel-cellcontact between EPCs and BMSCs could be observed during the process of the cellsheet preparation. The harvested sheet was composed of multiple layers of cells and cel-produced extracellular matrix. Alkaline phosphatase assay and alizarin red staining both demonstrated that EPCs/BMSCs sheet had good osteogenic differentiation ability. These results suggested that EPCs/BMSCs sheet can be constructed successful y, and the sheet has strong osteogenic differentiation capability in vitro, providing the foundation for the repair of bone defects.