Heparan sulfate acts as an activator of the NLRP3 inflammasome promoting inflammatory response in the development of acute pancreatitis.

BACKGROUND: Accumulating evidence has shown that the NOD-like receptor protein 3 (NLRP3) inflammasome plays a crucial role in the inflammatory cascades involved in the development of acute pancreatitis (AP). However, the specific agonist responsible for activating the NLRP3 inflammasome in this process has not yet been identified. The purpose of this study is to clarify whether heparan sulfate (HS) works as an NLRP3 inflammasome activator to evoke inflammatory cascades in the progression of AP. METHODS: Two experimental mouse models of AP were utilized to investigate the pro-inflammatory activity of HS in the development of AP by measuring the secretion of inflammatory cytokines and the neutrophil infiltration in pancreatic tissue. The ability of HS to activate the NLRP3 inflammasome was evaluated both in vitro and in vivo. The nuclear factor kappa B (NF-κB)-mediated expression of NLRP3 inflammasome components in response to HS treatment was determined to decipher the role of HS in transcriptional priming of NLRP3 inflammasome. Furthermore, HS-triggered deubiquitination of NLRP3 was analyzed to reveal the promoting effect of HS on the NLRP3 inflammasome priming via a non-transcriptional pathway. RESULTS: High plasma level of HS was observed with a positive correlation to that of inflammatory cytokines in AP mice. Administration of HS to mice resulted in an exacerbated inflammatory profile, while reducing HS production by an inhibitor of heparanase significantly attenuated inflammatory response. Pharmacological inhibition or genetic deletion of NLRP3 substantially suppressed the HS-stimulated elevation of IL-1ß levels in AP mice. The in vitro data demonstrated that HS primarily serves as a priming signal for the activation of the NLRP3 inflammasome. HS possesses the ability to increase the transcriptional activity of NF-κB and TLR4/NF-κB-driven transcriptional pathway is employed for NLRP3 inflammasome priming. Moreover, HS-induced deubiquitination of NLRP3 is another pathway responsible for non-transcriptional priming of NLRP3 inflammasome. CONCLUSIONS: Our current work has unveiled HS as a new activator of the NLRP3 inflammasome responsible for the secondary inflammatory cascades during the development of AP, highlighting the HS-NLRP3 pathway as a potential target for future preventive and therapeutic approaches of AP.

Abdominal paracentesis drainage improves outcome of acute pancreatitis complicated with intra-abdominal hypertension in early phase.

BACKGROUND: Intra-abdominal hypertension (IAH) is an important risk factor for organ dysfunction, and it occurs in the early phase of severe acute pancreatitis (SAP). We have reported a novel step-up approach and shown the benefit of performing abdominal paracentesis drainage (APD) ahead of percutaneous catheter drainage (PCD) when treating Patients with SAP with fluid collections. This study aimed to evaluate the efficacy of APD in Patients with SAP complicated with IAH in the early phase. METHODS: In the present study, 206 AP patients complicated with IAH in the early phase were enrolled in hospital between June 2017 and December 2020. The patients were divided into two groups: 109 underwent APD (APD group) and 97 were managed without APD (non-APD group). We retrospectively compared the outcomes of the APD and non-APD groups for IAH treatment. The parameters including mortality, infection, organ failure, inflammatory factors, indications for further interventions, and drainage-related complications were observed. RESULTS: The demographic data and severity scores of the two groups were comparable. The mortality rate was lower in the APD group (3.7%) than in the non-APD group (8.2%). Compared with the non-APD group, the intra-abdominal pressure and laboratory parameters of the APD group decreased more rapidly, and the mean number of failed organs was lower. However, there was no significant difference in incidence of infections between the two groups. CONCLUSIONS: Application of APD is beneficial to AP patients. It significantly attenuated inflammation injury, avoided further interventions, and reduced multiple organ failure.

Mechanisms of ferroptosis in chronic kidney disease.

Ferroptosis is a newly identified form of regulated cell death characterized by iron accumulation and lipid peroxidation. Ferroptosis plays an essential role in the pathology of numerous diseases and has emerged as a key area of focus in studies of chronic kidney disease (CKD). CKD is a major public health problem with high incidence and mortality that is characterized by a gradual loss of kidney function over time. The severity and complexity of CKD combined with the limited knowledge of its underlying molecular mechanism(s) have led to increased interest in this disease area. Here, we summarize recent advances in our understanding of the regulatory mechanism(s) of ferroptosis and highlight recent studies describing its role in the pathogenesis and progression of CKD. We further discuss the potential therapeutic benefits of targeting ferroptosis for the treatment of CKD and the major hurdles to overcome for the translation of in vitro studies into the clinic.

Epigallocatechin-3-gallate attenuates acute pancreatitis induced lung injury by targeting mitochondrial reactive oxygen species triggered NLRP3 inflammasome activation.

Green tea has been considered as a health-promoting beverage and is widely consumed worldwide. Epigallocatechin-3-gallate (EGCG), the most abundant polyphenol derived from green tea leaves with potent antioxidative and chemopreventive activities, has been reported to offer protection against inflammation-driven tissue damage. Here, we evaluated the protective effects of EGCG against lung injury during acute pancreatitis (AP) and further revealed the detailed mechanism. The results showed that EGCG significantly attenuated l-arginine-induced AP and the consequent pulmonary damage in mice. Moreover, EGCG substantially attenuated oxidative stress and concurrently suppressed NOD-like receptor protein 3 (NLRP3) inflammasome activation in the lung. In vitro, EGCG considerably reduced the production of mitochondrial reactive oxygen species (mtROS) and oxidized mitochondrial DNA (ox-mtDNA) in alveolar macrophages (AMs) challenged with AP-conditioned plasma. Meanwhile, the amount of ox-mtDNA bound to NLRP3 decreased significantly by the treatment with EGCG, resulting in impaired NLRP3 inflammasome activation. In addition, the antagonism of NLRP3 signaling by EGCG was affected in the presence of the mtROS stimulant rotenone or scavenger Mito-TEMPO. Altogether, EGCG possesses potent activity to attenuate lung injury during AP progression by inhibiting NLRP3 inflammasome activation. As for the mechanism, the EGCG-conferred restriction of NLRP3 inflammasome activation probably arises from the elimination of mtROS as well as its oxidative product ox-mtDNA, which consequently enables the protection against AP-associated lung injury.

Abdominal paracentesis drainage attenuates intestinal inflammation in rats with severe acute pancreatitis by inhibiting the HMGB1-mediated TLR4 signaling pathway.

BACKGROUND: Our previous studies confirmed that abdominal paracentesis drainage (APD) attenuates intestinal mucosal injury in rats with severe acute pancreatitis (SAP), and improves administration of enteral nutrition in patients with acute pancreatitis (AP). However, the underlying mechanisms of the beneficial effects of APD remain poorly understood. AIM: To evaluate the effect of APD on intestinal inflammation and accompanying apoptosis induced by SAP in rats, and its potential mechanisms. METHODS: SAP was induced in male adult Sprague-Dawley rats by 5% sodium taurocholate. Mild AP was induced by intraperitoneal injections of cerulein (20 µg/kg body weight, six consecutive injections). Following SAP induction, a drainage tube connected to a vacuum ball was placed into the lower right abdomen of the rats to build APD. Morphological changes, serum inflammatory mediators, serum and ascites high mobility group box protein 1 (HMGB1), intestinal barrier function indices, apoptosis and associated proteins, and toll-like receptor 4 (TLR4) signaling molecules in intestinal tissue were assessed. RESULTS: APD significantly alleviated intestinal mucosal injury induced by SAP, as demonstrated by decreased pathological scores, serum levels of D-lactate, diamine oxidase and endotoxin. APD reduced intestinal inflammation and accompanying apoptosis of mucosal cells, and normalized the expression of apoptosis-associated proteins in intestinal tissues. APD significantly suppressed activation of the intestinal TLR4 signaling pathway mediated by HMGB1, thus exerting protective effects against SAP-associated intestinal injury. CONCLUSION: APD improved intestinal barrier function, intestinal inflammatory response and accompanying mucosal cell apoptosis in SAP rats. The beneficial effects are potentially due to inhibition of HMGB1-mediated TLR4 signaling.

Plasma-derived exosomes contribute to pancreatitis-associated lung injury by triggering NLRP3-dependent pyroptosis in alveolar macrophages.

Progression of acute pancreatitis (AP) into a severe form usually results in a life-threatening condition with multiple organ dysfunction, and in particular acute lung injury (ALI), often contributes to the majority of AP-associated deaths. Increasing evidence has shown that uncontrolled activation of the immune system with rapid production of inflammatory cytokines play a dominant role in this process. As an intracellular inflammatory signaling platform, the NOD-like receptor protein 3 (NLRP3) inflammasome, is recently reported to be involved in the pathogenesis of AP progression, however, the relationship between NLRP3 inflammasome activation and AP-associated lung injury remains unclear yet. Here, we show that NLRP3 inflammasome activation and subsequent pyroptosis in alveolar macrophages (AMs) is responsible for the lung injury secondary to AP. In addition, plasma-derived exosomes from AP mice is capable of triggering NLRP3-dependent pyroptosis in AMs. Inhibition of exosome release or uptake in vivo by inhibitors substantially suppresses AMs pyroptosis and thereby alleviates AP-induced pulmonary lesion. Collectively, the current work reveals for the first time the involvement of NLRP3-dependent pyroptosis induced by plasma exosomes in the pathogenesis of AP-induced ALI, suggesting that the exosome-mediated NLRP3 inflammatory pathway is a potential therapeutic target for the treatment of lung injury during AP.

Bile Acid Transporters Are Expressed and Heterogeneously Distributed in Rat Bile Ducts.

Background/Aims: Cholangiocytes are capable of reabsorbing bile salts from bile, but the pathophysiological significance of this process is unclear. To this end, we detected the expression and distribution of bile acid transport proteins in cholangiocytes from normal rat liver and analyzed the possible pathophysiological significance. Methods: Bile duct tissues of Sprague-Dawley rats were isolated by enzymatic digestion and mechanical isolation, and then divided into large and small bile duct tissues. Immunohistochemistry, real-time polymerase chain reaction and Western blotting were used to determine the expression of the apical sodium-dependent bile acid transporter (ASBT), ileal bile acid binding protein (IBABP), and basolateral organic solute transporter α (Ostα) in the biliary tract system of rats. Differences in the expression and distribution of these proteins were analyzed. Results: In cholangiocytes, ASBT and IBABP were mainly expressed in cholangiocytes of the large bile ducts, in which the expression of both was significantly higher than that in the small ducts (p<0.05). Ostα was simultaneously expressed in cholangiocytes of both the large and small bile ducts, showing no significant difference in expression between the two groups of bile ducts (p>0.05). Conclusions: Bile acid transporters are expressed and heterogeneously distributed in rat bile ducts, indicating that bile acid reabsorption by cholangiocytes might mainly occur in the large bile ducts. These findings may help explore the physiology of bile ducts and the pathogenesis of various cholangiopathies.

The Role of Exogenous Hydrogen Sulfide in Free Fatty Acids Induced Inflammation in Macrophages.

BACKGROUND: This study aimed to investigate whether exogenous hydrogen sulfide (H2S) can protect the RAW264.7 macrophages against the inflammation induced by free fatty acids (FFA) by blunting NLRP3 inflammasome activation via a specific TLR4/NF-κB pathway. METHODS: RAW264.7 macrophages were exposed to increasing concentrations of FFA for up to 3 days to induce FFA-induced inflammation. The cells were pretreated with NaHS (a donor of H2S) before exposure to FFA. Cell viability, cell apoptosis, TLR4, NF-κB, NLRP3 inflammasome, IL-1ß, IL-18 and cleaved caspase-3 expression were measured by a combination of MTT assay, ELISA, and immunoblotting. RESULTS: H2S attenuated FFA-induced cell apoptosis, and reduced the expression of NLRP3, ASC, pro-caspase-1, caspase-1, IL- 1ß, IL-18 and caspase-3. In addition, H2S inhibited the FFA-induced activation of TLR4 and NF-κB. Furthermore, NLRP3 inflammasome activation was regulated by the TLR4 and NF-κB pathway. CONCLUSION: The present study demonstrated for the first time that H2S appears to suppress FFA-induced macrophage inflammation and apoptosis by inhibiting the TLR4/ NF-κB pathway and its downstream NLRP3 inflammasome activation. Thus H2S might possess potential in the treatment of diseases resulting from FFA overload like insulin resistance and type diabetes.

The E3 ubiquitin ligase NEDD4 is translationally upregulated and facilitates pancreatic cancer.

AIM: To determine the regulation and function of the neural precursor cell expressed developmentally down regulated protein 4 (NEDD4) in PDAC and to determine its dependency on phosphatase and tensin homolog (PTEN) and PI3K/AKT signaling. METHODS: We investigated the expression of NEDD4 and the tumor suppressor PTEN in normal immortalized human pancreatic duct epithelial cell line and pancreatic adenocarcinoma (PDAC) cell lines. We further evaluated whether RNAi-mediated depletion of NEDD4 can attenuate PDAC cell proliferation and migration. We subsequently determined the crosstalk between NEDD4 expression and the PTEN/PI3K/AKT signaling pathway. Finally, we determined the mechanism behind differential NEDD4 protein expression in pancreatic cancer. RESULTS: The expression of NEDD4 was heterogeneous in PDAC cells, but was significantly higher compared to normal pancreatic ductal epithelial cells. Analogically, PTEN was decreased in the PDAC cells. A combination of MTT assay, wound healing migration assay, and transwell invasion assays confirmed that depletion of NEDD4 decreased the proliferation and migration ability of PDAC cells. Western blot and immunofluorescence results revealed that NEDD4 could affect PTEN/PI3K/AKT signaling pathway in PDAC cells. Polysomal profiling revealed that higher NEDD4 protein expression in PDAC cells was due to undefined mechanism involving translational activation. CONCLUSIONS: Our results reveal a novel mechanism of upregulation of NEDD4 expression in PDAC. Our findings indicate that NEDD4 potentially plays a critical role in activating the PI3K/AKT signaling pathway by negatively regulating PTEN levels in PDAC cells, which promotes pancreatic cancer cell proliferation and metastasis. Therefore, NEDD4 may be a potential therapeutic target in PDAC.

Outcome benefit of abdominal paracentesis drainage for severe acute pancreatitis patients with serum triglyceride elevation by decreasing serum lipid metabolites.

BACKGROUND: Our previous reports demonstrated that abdominal paracentesis drainage (APD) exerts a beneficial effect on severe acute pancreatitis (SAP) patients. However, the underlying mechanisms for this effectiveness are not well understood. METHODS: A retrospective cohort of 132 consecutive non-hypertriglyceridemia (HTG)-induced SAP patients with triglyceride (TG) elevation and pancreatitis-associated ascitic fluid (PAAF) was recruited from May 2010 to May 2015 and included in this study. The patients were divided into two groups: the APD group (n = 68) and the non-APD group (n = 64). The monitored parameters mainly included mortality, hospital stay, the incidence of further intervention, levels of serum lipid metabolites and inflammatory factors, parameters related to organ failure and infections, and severity scores. RESULTS: The demographic data and severity scores were comparable between the two groups. Compared with the non-APD group, the primary outcomes (including mortality, hospital stay and the incidence of percutaneous catheter drainage) in the APD group were improved. The serum levels of lipid metabolites were significantly lower in the APD group after 2 weeks of treatment than in the non-APD group. Logistic regression analysis indicated that the decreased extent of free fatty acid (FFA)(odds ratio, 1.435; P = 0.015) was a predictor of clinical improvement after 2 weeks of treatment. CONCLUSION: Treatment with APD benefits non-HTG-induced SAP patients with serum TG elevation by decreasing serum levels of FFA.

Negative correlation of ITCH E3 ubiquitin ligase and miRNA-106b dictates metastatic progression in pancreatic cancer.

Pancreatic cancer is one of the major malignancies and cause for mortality across the world, with recurrence and metastatic progression remaining the single largest cause of pancreatic cancer mortality. Hence it is imperative to develop novel biomarkers of pancreatic cancer prognosis. The E3 ubiquitin ligase ITCH has been previously reported to inhibit the tumor suppressive Hippo signaling by suppressing LATS1/2 in breast cancer and chronic lymphocytic leukemia. However, the role of ITCH in pancreatic cancer progression has not been described. Here we report that ITCH transcript and protein expression mimic metastatic trait in pancreatic cancer patients and cell lines. Loss-of-function studies of ITCH showed that the gene product is responsible for inducing metastasis in vivo. We furthermore show that hsa-miR-106b, which itself is down regulated in metastatic pancreatic cancer, directly interacts and inhibit ITCH expression. ITCH and hsa-miR-106b are thus potential biomarkers for pancreatic cancer prognosis.

Hydrogen-rich saline protects against ischemia/reperfusion injury in grafts after pancreas transplantations by reducing oxidative stress in rats.

PURPOSE: This study aimed to investigate the therapeutic potential of hydrogen-rich saline on pancreatic ischemia/reperfusion (I/R) injury in rats. METHODS: Eighty heterotopic pancreas transplantations (HPT) were performed in syngenic rats. The receptors were randomized blindly into the following three groups: the HPT group and two groups that underwent transplantation and administration of hydrogen-rich saline (HS, >0.6 mM, 6 mL/kg) or normal saline (NS, 6 mL/kg) via the tail vein at the beginning of reperfusion (HPT + HS group, HPT + NS group). Samples from the pancreas and blood were taken at 12 hours after reperfusion. The protective effects of hydrogen-rich saline against I/R injury were evaluated by determining the changes in histopathology and measuring serological parameters, oxidative stress-associated molecules, and proinflammatory cytokines. RESULTS: Administration of hydrogen-rich saline produced notable protection against pancreatic I/R injury in rats. Histopathological improvements and recovery of impaired pancreatic function were observed. In addition, TNF-α, IL-1ß, and IL-6 were reduced markedly in the HPT + HS group. Additionally, there were noticeable inhibitory effects on the pancreatic malondialdehyde level and considerable recruitment of SOD and GPx, which are antioxidants. CONCLUSION: Hydrogen-rich saline treatment significantly attenuated the severity of pancreatic I/R injury in rats, possibly by reducing oxidative stress and inflammation.

Effects of treatment with hydrogen sulfide on methionine-choline deficient diet-induced non-alcoholic steatohepatitis in rats.

BACKGROUND AND AIM: Oxidative stress and inflammation play important roles in the progression from simple fatty liver to non-alcoholic steatohepatitis (NASH). The aim of this work was to investigate whether treatment with hydrogen sulfide (H2 S) prevented NASH in rats through abating oxidative stress and suppressing inflammation. METHODS: A methionine-choline-deficient (MCD) diet rat model was prepared. Rats were divided into three experimental groups and fed for 8 weeks as follows: (i) control rats; (ii) MCD-diet-fed rats; (iii) MCD-diet-fed rats treated with NaHS (intraperitoneal injection of 0.1 mL/kg/day of 0.28 mol/L NaHS, a donor of H2 S). RESULTS: MCD diet impaired hepatic H2 S biosynthesis in rats. Treatment with H2 S prevented MCD-diet-induced NASH, as evidenced by hematoxylin and eosin staining, reduced apoptosis and activities of alanine aminotransferase and aspartate aminotransferase, and attenuated hepatic fat accumulation in rats. Treatment with H2 S abated MCD-diet-induced oxidative stress through reducing cytochrome p4502E1 expression, enhancing heme oxygenase-1 expression, and suppressing mitochondrial reactive oxygen species formation, and suppressed MCD-diet-induced inflammation through suppressing activated nuclear factor κB signaling and reducing interleukin-6 and tumor necrosis factor α expressions. In addition, treatment of MCD-diet fed rats with H2 S had a beneficial modulation on expression profiles of fatty acid metabolism genes in livers. CONCLUSIONS: Treatment with H2 S prevented NASH induced by MCD diet in rats possibly through abating oxidative stress and suppressing inflammation.

Progressive balloon dilatation following hepaticojejunostomy improves outcome of bile duct stricture after iatrogenic biliary injury.

BACKGROUND: Iatrogenic biliary stricture (IBS) is a disastrous complication of cholecystectomy. Although the endoscopic treatments are well accepted as initial attempts for IBS, surgical hepaticojejunostomy (HJ) is often necessary for a considerable proportion of patients. However, the anastomotic stricture after HJ also occurs. METHODS: In the present study, a new procedure, progressive balloon dilation following HJ (HJPBD), was designed and utilized in the IBS treatment. We retrospectively compared HJPBD with the traditional HJ in term of the outcomes when used for IBS treatment. RESULTS: Between January 1997 and December 2009, 112 patients with IBS attributed to cholecystectomy enrolled in our hospital were treated with surgical reconstruction with either HJ (n=58) or HJPBD (n=54). Of the 58 patients in HJ group, 48 patients (82.8%) had a successful outcome, while 52 out of 54 patients (96.3%) in HJPBD group achieved success. The successful surgical reconstruction rates were significantly different between these two groups, with a further improved outcome in patient undergone progressive balloon dilation following HJ. Additionally, 8 of the 10 failure cases in HJ group were successfully rescued by HJPBD procedure. CONCLUSIONS: Our findings suggest that the new procedure of HJPBD could be successfully applied to IBS patients, and significantly improve the outcome of IBS reconstruction.

[Protective effect of Ligustrazine preconditioning on hepatic energy metabolism in ischemia/reperfusion injury of rat].

OBJECTIVE: Objective to investigate the protective effects of Ligustrazine preconditioning against hepatic ischemia/reperfusion injury (IRI) in rats. METHODS: Fifty male Wistar rats were randomly allocated into 3 groups: sham operation group, in which animals underwent laparotomy, experimental group and control group in which were treated with 70% IRI of the liver, especially, the animals in experimental group was given intraperitoneal injection of 2 mL Ligustrazine per day for 3 days before operation. After the operation, liver tissues were harvested at 1 h, 6 h, 24 h and 72 h for the study of histomorphological change, the respiratory control ratio (RCR) and phosphorus: oxygen ratio (P/O) of hepatocytes mitochondria, and the contents of adenosine triphosphate (ATP) of liver tissue. RESULTS: (1) The damage hepatic tissue in experimental group was slighter than that in control group at each corresponding time-point after operation. (2) The RCR and P/O ratio at each corresponding time-point were higher in experimental group than those in control group (P < 0.05), and all of the two groups recovered after 72 h. (3) The ATP concentration in experimental group also was higher than that in control group at each corresponding time-point, and recovered faster than control group. CONCLUSION: The current results show that Ligustrazine preconditioning may improve energy metabolism of rat liver in ischemia reperfusion injury.

[Effect of 90 percentage portal branch ligation on liver regeneration and expression of metalloproteinase and tissue inhibitors of metalloproteinases in rats].

OBJECTIVE: To investigate the effect of 90% portal branch ligation on liver regeneration and expression of metalloproteinases and tissue inhibitors of metalloproteinases in rats. METHODS: Ninety-six SD rats were randomly divided into Sham-PBL group and portal vein branches ligation group. The weight of both ligated and unligated lobes of liver were measured at post operation day (POD) 0.5, 1, 3, 5, 7, 14, 21 and 28. The morphological changes of the non-ligated liver lobes were observed by microscope. The expression of PCNA, MMP2, MMP9 and TIMP2 of the non-ligated liver lobes were studied by immunohistochemistry. RESULTS: 1) 95.8% rats survived from the ligation of 90% portal branch. Hepatic lobe at the ligated side diminished progressively after ligation, whereas the lobes of the unligated side underwent compensatory regeneration. The ratio of non-ligated lobes weight to the whole liver increased slowly within 1d, speeded up significantly during 1-5d period, increased slowly after POD5, and got the plateau stag at POD7; 2) PCNA index were markedly increased within POD 0.5-3 (P < 0.01). It reached the peak at POD5 and decreased slightly at POD7, but still higher than Sham-PBL group level, then gradually returned to normal. 3) The expression of MMP2,MMP9 and TIMP2 in the non-ligated liver lobes were markedly increased at 1d. It reached the peak at POD7 and gradually returned to normal within POD7-28. 4) The MMP2 and PCNA in liver had a positive correlation at POD 0.5, 1, 5, 7, 14. The expressions of MMP9 and PCNA had a positive correlation at POD 0.5, 1, 7, 21. CONCLUSION: The expressions of TIMP2 and PCNA had a positive correlation at POD1, 7, 14, 21. The expression of MMP2, MMP9 and TIMP2 of the non-ligated liver lobes is markedly increased at POD1. It reaches the peak at POD7, and dropped to normal level gradually. The expressions of MMP2, MMP9 and TIMP2 and PCNA were correlated in 90% portal branch Ligation rats. The expression of MMP2,MMP9 and TIMP2 may play a pivotal role in liver regeneration.

[Development of an electrolytically-detachable microcoil for intracranial aneurysms].

An electrolytically-detachable microcoil is introduced here in the paper. The testing results indicate that, the microcoils have stable mechanical properties, clear radiographic images and fine insulation performance. Their detaching time varies from 30s to 200s when voltage changes from 2V to 5V.