Role of albumin-bilirubin score in non-malignant liver disease

The albumin-bilirubin (ALBI) score, which was proposed to assess the prognosis of patients with hepatocellular carcinoma, has gradually been extended to other liver diseases in recent years, including primary biliary cholangitis, liver cirrhosis, hepatitis, liver transplantation, and liver injury. The ALBI score is often compared with classical scores such as the Child-Pugh and model for end-stage liver disease scores or other noninvasive prediction models. It is widely employed because of its immunity to subjective evaluation indicators and ease of obtaining detection indicators. An increasing number of studies have confirmed that it is highly accurate for assessing the prognosis of patients with chronic liver disease; additionally, it has demonstrated good predictive performance for outcomes beyond survival in patients with liver diseases, such as decompensation events. This article presents a review of the application of ALBI scores in various non-malignant liver diseases.

Circulating tumor cells as potential prognostic biomarkers for early-stage pancreatic cancer: A systematic review and meta-analysis

BACKGROUND

Pancreatic cancer is difficult to be diagnosed early clinically, while often leads to poor prognosis. If optimal personalized treatment plan can be provided to pancreatic cancer patient at an earlier stage, this can greatly improve overall survival (OS). Circulating tumor cells (CTCs) are a collective term for various types of tumor cells present in the peripheral blood (PB), which are formed by detachment during the development of solid tumor lesions. Most CTCs undergo apoptosis or are phagocytosed after entering the PB, whereas a few can escape and anchor at distal sites to develop metastasis, increasing the risk of death for patients with malignant tumors.

AIM

To investigate the significance of CTCs in predicting the prognosis of early pancreatic cancer patients.

METHODS

The PubMed, EMBASE, Web of Science, Cochrane Library, China National Knowledge Infrastructure, China Biology Medicine, and ChinaInfo databases were searched for articles published through December 2022. Studies were considered qualified if they included patients with early pancreatic cancer, analyzed the prognostic value of CTCs, and were full papers reported in English or Chinese. Researches were selected and assessed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses protocol and the Newcastle-Ottawa Scale criteria. We used a funnel plot to assess publication bias.

RESULTS

From 1595 publications, we identified eight eligible studies that collectively enrolled 355 patients with pancreatic cancer. Among these original studies, two were carried out in China; three in the United States; and one each in Italy, Spain, and Norway. All eight studies analyzed the relevance between CTCs and the prognosis of patients with early-stage pancreatic cancer after surgery. A meta-analysis showed that the patients that were positive pre-treatment or post-treatment for CTCs were associated with decreased OS [hazard ratio (HR) = 1.93, 95% confidence interval (CI): 1.197-3.126, P = 0.007] and decreased relapse-free/disease-free/progression-free survival (HR = 1.27, 95%CI: 1.137-1.419, P < 0.001) in early-stage pancreatic cancer. Additionally, the results suggest no statistically noticeable publication bias for overall, disease-free, progression-free, and recurrence-free survival.

CONCLUSION

This pooled meta-analysis shows that CTCs, as biomarkers, can afford reliable prognostic information for patients with early-stage pancreatic cancer and help develop individualized treatment plans.

Efficacy of endoscopic ultrasound in the evaluation of small gastrointestinal stromal tumors

BACKGROUND

Gastrointestinal stromal tumors (GISTs) with a diameter of < 2 cm are called small GISTs. Currently, endoscopic ultrasound (EUS) is widely used as a regular follow-up method for GISTs, which can also provide a preliminary basis for judging the malignancy potential of lesions. However, there are no studies on the accuracy of EUS to assess the malignant potential of small GISTs.

AIM

To evaluate the efficacy of EUS in the diagnosis and risk assessment of small GISTs.

METHODS

We collected data from patients with small GISTs who were admitted to Shengjing Hospital of China Medical University between October 2014 and July 2019. The accurate diagnosis and risk classifications of patients were based on the pathological assessment according to the modified National Institute of Health criteria after endoscopic resection or laparoscopic surgery. Preoperative EUS features (marginal irregularity, cystic changes, homogeneity, ulceration, and strong echogenic foci) were retrospectively analyzed. The assessment results based on EUS features were compared with the pathological features.

RESULTS

A total of 256 patients (69 men and 187 women) were enrolled. Pathological results included 232, 16, 7, and 1 very low-, low-, intermediate-, and high-risk cases, respectively. The most frequent tumor location was the gastric fundus (78.1%), and mitoses were calculated as > 5/50 high power field in 8 (3.1%) patients. Marginal irregularity, ulceration, strong echo foci, and heterogeneity were detected in 1 (0.4%), 2 (0.8%), 22 (8.6%), and 67 (65.1%) patients, respectively. However, cystic changes were not detected. Tumor size was positively correlated with the mitotic index (P < 0.001). Receiver operating curve analysis identified 1.48 cm as the best cut-off value to predict malignant potential (95% confidence interval: 0.824–0.956). EUS heterogeneity with tumor diameters > 1.48 cm was associated with higher risk classification (P < 0.05).

CONCLUSION

Small GISTs (diameters > 1.48 cm) with positive EUS features should receive intensive surveillance or undergo endoscopic surgery. EUS and dissection are efficient diagnostic and therapeutic approaches for small GISTs.

[Recommendations of diagnosis and treatment of polyarteritis nodosa]

Polyarteritis nodosa (PAN) is a rare vasculitis that mainly involves small and medium arteries. It often occurs at the points where the vessels bifurcate, leading to microaneurysm formation, thrombosis, aneurysm rupture and bleeding, and infarction of organs.About a third of cases are associated with hepatitis B virus (HBV) infection.All tissues and organs of the body can be affected, with skin, joints and peripheral nerves being the most common.The pathological changes were fibrinoid necrosis, inflammatory cell infiltration and luminal thrombosis in the acute stage, and fibrous hyperplasia in the chronic stage.Overall outcomes for the disease have improved in recent decades, mainly reflecting early diagnosis and more effective treatments.The main treatments for PAN are glucocorticoid and cyclophosphamide.Patients with HBV-associated PAN should receive antiviral therapy and plasma exchange.

[Survival analysis of unexpected small cell lung cancer following surgery]

Objective: To investigate the survival and influencing factors of unexpected small cell lung cancer following surgery. Methods: We respectively reviewed the clinical characters of 104 patients who underwent surgical treatment and be proved as small cell lung cancer by pathology between January 2000 to October 2020 in Chinese PLA General Hospital. Overall survival (OS) of patients was evaluated using Kaplan-Meier and Cox proportional hazards analysis. Results: Of 104 patients, 27 cases showed central lesions, and other 77 showed peripheral nodules. The margin of nodules was smooth in 42 cases on CT imaging. The median OS was 34.3 months and 5-year OS rate was 45.8%. Postoperative 5-year OS rates for patients were 52.1%, 45.4%, and 27.8% for clinical stages Ⅰ, Ⅱ, and Ⅲ, respectively. Univariate analyses identified the age, surgical access, surgical approach, N stage, TNM stage and vascular cancer emboli were associated with OS (P<0.05). The N stage was an independent factor for the OS of patients (P<0.05). Conclusions: Patients with unexpected SCLC, including Ⅰ, Ⅱ and part ⅢA stage have favorable outcome and can benefit from surgery and systemic postoperative treatment. Standard lobectomy plus systemic lymph node dissection is commended.

Molecular regulatory mechanism of ferroptosis and its role in gastrointestinal oncology: Progress and updates

Gastrointestinal (GI) tumors, including liver, pancreatic, gastric, and colorectal cancers, have a high incidence rate and low survival rate due to the lack of effective therapeutic methods and frequent relapses. Surgery and postoperative chemoradiotherapy have largely reduced the fatality rates for most GI tumors, but these therapeutic approaches result in poor prognoses due to severe adverse reactions and the development of drug resistance. Recent studies have shown that ferroptosis plays an important role in the onset and progression of GI tumors. Ferroptosis is a new non-apoptotic form of cell death, which is iron-dependent, non-apoptotic cell death characterized by the accumulation of lipid reactive oxygen species (ROS). The activation of ferroptosis can lead to tumor cell death. Thus, regulating ferroptosis in tumor cells may become a new therapeutic approach for tumors, making it become a research hotspot. Current studies suggest that ferroptosis is mainly triggered by the accumulation of lipid ROS. Furthermore, several studies have indicated that ferroptosis may be a new approach for the treatment of GI tumors. Here, we review current research progress on the mechanism of ferroptosis, current inducers and inhibitors of ferroptosis, and the role of ferroptosis in GI tumors to propose new methods for the treatment of such tumors.

Scoparone inhibits pancreatic cancer through PI3K/Akt signaling pathway

BACKGROUND

Pancreatic cancer is a highly malignant tumor of the gastrointestinal system whose emerging resistance to chemotherapy has necessitated the development of novel antitumor treatments. Scoparone, a traditional Chinese medicine monomer with a wide range of pharmacological properties, has attracted considerable attention for its antitumor activity.

AIM

To explore the potential antitumor effect of scoparone on pancreatic cancer and the possible molecular mechanism of action.

METHODS

The target genes of scoparone were determined using both the bioinformatics and multiplatform analyses. The effect of scoparone on pancreatic cancer cell proliferation, migration, invasion, cell cycle, and apoptosis was detected in vitro. The expression of hub genes was tested using quantitative reverse transcription polymerase chain reaction (qRT-PCR), and the molecular mechanism was analyzed using Western blot. The in vivo effect of scoparone on pancreatic cancer cell proliferation was detected using a xenograft tumor model in nude mice as well as immunohistochemistry.

RESULTS

The hub genes involved in the suppression of pancreatic cancer by scoparone were obtained by network bioinformatics analyses using publicly available databases and platforms, including SwissTargetPrediction, STITCH, GeneCards, CTD, STRING, WebGestalt, Cytoscape, and Gepia; AKT1 was confirmed using qRT-PCR to be the hub gene. Cell Counting Kit-8 assay revealed that the viability of Capan-2 and SW1990 cells was significantly reduced by scoparone treatment exhibiting IC50 values of 225.2 μmol/L and 209.1 μmol/L, respectively. Wound healing and transwell assays showed that scoparone inhibited the migration and invasion of pancreatic cancer cells. Additionally, flow cytometry confirmed that scoparone caused cell cycle arrest and induced apoptosis. Scoparone also increased the expression levels of Bax and cleaved caspase-3, decreased the levels of MMP9 and Bcl-2, and suppressed the phosphorylation of Akt without affecting total PI3K and Akt. Moreover, compared with the control group, xenograft tumors, in the 200 μmol/L scoparone treatment group, were smaller in volume and lighter in weight, and the percentages of Ki65- and PCNA-positive cells were decreased.

CONCLUSION

Our findings indicate that scoparone inhibits pancreatic cancer cell proliferation in vitro and in vivo, inhibits migration and invasion, and induces cycle arrest and apoptosis in vitro through the PI3K/Akt signaling pathway.

Stent placement to prevent strictures after esophageal endoscopic submucosal dissection: a systematic review and meta-analysis

Endoscopic submucosal dissection (ESD) is an important method for the treatment of early esophageal cancer. However, post-procedure stenosis is one of the most common long-term complications. This meta-analysis aimed to investigate whether stent placement is effective in the stenosis prevention, and which type of stent would be more effective. A systematic and electronic search of clinical trials and observational studies conducted before March 2020 on the efficacy of stent placement in preventing esophageal stricture after ESD was performed. Search terms included "ESD," "esophageal stenosis," "esophageal stricture," and "stents." We conducted a bias risk assessment of the eligible reports and a meta-analysis of the data using Revman 5.3 software. We included two randomized controlled trials (RCTs) and a prospective cohort study involving 163 patients with esophageal mucosal defects encompassing at least three-quarters of the esophagus circumference after ESD. The meta-analysis results showed that post-ESD stenosis rates (RR, 0.37; 95% CI, 0.22-0.64; P = 0.0003) and the number of endoscopic balloon dilations (EBDs) (MD, -1.74; 95% CI, -2.46 to -1.01; P < 0.00001) were reduced in the pooled analysis of three studies, indicating that stent placement was effective for stenosis prevention, especially a polyglycolic acid (PGA) sheet combined with stent placement can prevent stenosis (RR, 0.41; 95% CI, 0.23-0.74; P = 0.003) and reduce the number of EBDs (MD, -1.65; 95% CI, -2.40 to -0.90; P < 0.0001) significantly. Stent placement can reduce the rate of esophageal stenosis after ESD, especially when stents are covered with PGA sheets. However, more high-quality, low-bias RCTs with a sufficient sample size are needed to demonstrate its effectiveness.

Comprehensive review of diagnostic modalities for early chronic pancreatitis

Chronic pancreatitis (CP) is a progressive condition caused by several factors and characterised by pancreatic fibrosis and dysfunction. However, CP is difficult to diagnose at an early stage. Various advanced methods including endoscopic ultrasound based elastography and confocal laser endomicroscopy have been used to diagnose early CP, although no unified diagnostic standards have been established. In the past, the diagnosis was mainly based on imaging, and no comprehensive evaluations were performed. This review describes and compares the advantages and limitations of the traditional and latest diagnostic modalities and suggests guidelines for the standardisation of the methods used to diagnose early CP.

Endoscopic full-thickness resection using an over-the-scope device: A prospective study

BACKGROUND

Endoscopic submucosal dissection to treat mucosal and submucosal lesions sometimes results in low rates of microscopically margin-negative (R0) resection. Endoscopic full-thickness resection (EFTR) has a high R0 resection rate and allows for the definitive diagnosis and treatment of selected mucosal and submucosal lesions that are not suitable for conventional resection techniques.

AIM

To evaluate the efficacy and safety of EFTR using an over-the-scope clip (OTSC).

METHODS

This prospective, single-center, non-randomized clinical trial was conducted at the endoscopy center of Shengjing Hospital of China Medical University. The study included patients aged 18-70 years who had gastric or colorectal submucosal tumors (SMTs) (≤ 20 mm in diameter) originating from the muscularis propria based on endoscopic ultrasound (EUS) and patients who had early-stage gastric or colorectal cancer (≤ 20 mm in diameter) based on EUS and computed tomography. All lesions were treated by EFTR combined with an OTSC for wound closure between November 2014 and October 2016. We analyzed patient demographics, lesion features, histopathological diagnoses, R0 resection (negative margins) status, adverse events, and follow-up results.

RESULTS

A total of 68 patients (17 men and 51 women) with an average age of 52.0 ± 10.5 years (32-71 years) were enrolled in this study, which included 66 gastric or colorectal SMTs and 2 early-stage colorectal cancers. The mean tumor diameter was 12.6 ± 4.3 mm. The EFTR procedure was successful in all cases. The mean EFTR procedure time was 39.6 ± 38.0 min. The mean OTSC defect closure time was 5.0 ± 3.8 min, and the success rate of closure for defects was 100%. Histologically complete resection (R0) was achieved in 67 (98.5%) patients. Procedure-related adverse events were observed in 11 (16.2%) patients. The average post-procedure length of follow-up was 48.2 ± 15.7 mo. There was no recurrence during follow-up.

CONCLUSION

EFTR combined with an OTSC is an effective and safe technique for the removal of select subepithelial and epithelial lesions that are not amenable to conventional endoscopic resection techniques.

[Clinical cure strategies for hepatitis B: direct-acting antiviral drugs]

Direct-acting antivirals (DAAs) play a critical role for the therapy of chronical hepatitis B. DAAs can decrease the production of viral progeny of hepatitis B virus (HBV), breaking the viral dynamic equilibrium between: (1) virion production from hepatocytes and clearance from circulation; (2) replenishment and decay of covalently closed circular (ccc)DNA pool inside infected hepatocytes. Nucleos(t)ide analogues can potently shift the first balance to undetectable viremia in the blood, but have limited or no effect on the second one, thus making it imperative to develop new agents targeting additional step(s) of HBV life cycle. We herein briefly introduce the DAAs currently in development by classifying them as agents affecting the replenishment or the decay of cccDNA pool.

Endoscopic fenestration in the diagnosis and treatment of delayed anastomotic submucosal abscess: A case report and review of literature

BACKGROUND

Abscess formation is one of the complications after radical resection of rectal cancer; cases with delayed postoperative anastomotic abscess are rare. Here, we report a rare case of postoperative anastomotic abscess with a submucosal neoplasm appearing after rectal surgery. Ultimately, the patient was diagnosed and treated by endoscopic fenestration. In addition, we review the literature on the appearance of an abscess as a complication after rectal cancer surgery.

CASE SUMMARY

A 57-year-old man with a history of rectal malignancy resection complained of a smooth protuberance near the anastomotic stoma. Endoscopic ultrasonography revealed a hypoechoic structure originating from the muscularis propria, and a submucosal tumor was suspected. The patient was subsequently referred to our hospital and underwent pelvic contrast-enhanced computed tomography, which revealed no thickening or strengthening of the anastomotic wall. In order to clarify the origin of the lesion and obtain the pathology, endoscopic fenestration was performed. After endoscopic procedure, a definitive diagnosis of delayed anastomotic submucosal abscess was established. The patient achieved good recovery and prognosis after the complete clearance of abscess.

CONCLUSION

Endoscopic fenestration may be safe and effective for the diagnosis/treatment of delayed intestinal smooth protuberance after rectal cancer surgery.

Endoscopic ultrasound-measured muscular thickness of the lower esophageal sphincter and long-term prognosis after peroral endoscopic myotomy for achalasia

BACKGROUND

People with achalasia typically have a thick lower esophageal muscularis propria (LEMP), and peroral endoscopic myotomy (POEM) has been effective in treating most patients. LEMP thickness may be associated with the outcomes and prognosis after POEM. However, more evidence is needed regarding the relationship between LEMP thickness and patient prognosis after POEM.

AIM

To assess the association between LEMP thickness, measured using endoscopic ultrasound (EUS), and long-term prognosis, especially relapse, after POEM for achalasia.

METHODS

All medical records, including EUS data, of patients who underwent POEM to treat achalasia at Shengjing Hospital of China Medical University from January 2012 to September 2018 were retrospectively reviewed. LEMP thickness was measured by EUS, and a thickness of ≥ 3 mm was defined as thickened. The severity of patient symptoms was evaluated using the Eckardt score. Relapse was defined as a 3-point rise in the Eckardt score after a period of clinical remission. The relationship between patient characteristics, muscle thickness, and recurrence was analyzed.

RESULTS

Eighty-two patients (32 males and 50 females, aged 17-78 years) and 85 POEM procedures were included. In total, 76.8% (63/82 patients) of patients had a thickened muscularis propria. Older age and longer disease course were associated with muscularis propria thickening (P < 0.05). The mean postoperative follow-up time was 35.4 ± 17.2 mo (range, 8-87.5 mo) in 60 patients. Five patients with Eckardt scores > 3 refused further management after their symptoms were relieved. The relapse rate was 12.73% (7/55 cases). Five patients, four of whom had muscularis propria thickening, had disease recurrence within 12 mo after the procedure. Achalasia relapsed in one patient who had a thickened muscularis propria after 24 mo and in another patient who did not have a thickened muscularis propria after 30 mo. Patients with recurrence were typically younger and had a shorter disease course (P < 0.05). The relapse rate in patients with a non-thickened muscularis propria tended to be higher (18.2%, 2/11 patients) than that in patients with a thickened muscularis propria (11.4%, 5/44 patients), although no significant difference was found. Age (hazard ratio = 0.92; 95% confidence interval: 0.865-0.979; P < 0.05) and being male (hazard ratio = 7.173; 95% confidence interval: 1.277-40.286; P < 0.05) were identified as risk factors for symptomatic recurrence by multivariable analysis using the Cox model.

CONCLUSION

Patients with a thickened muscularis are typically older and have a longer disease course. Younger age and the male sex are associated with increased recurrence. Patients with a thin muscularis propria may be prone to relapse, although further validation is needed.

Delayed perforation after endoscopic resection of a colonic laterally spreading tumor: A case report and literature review

BACKGROUND

Endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) have been widely used for the treatment of early gastrointestinal cancer. Endoscopic piecemeal mucosal resection (EPMR) is derived from the combination of EMR and ESD. Delayed perforation with peritonitis after colonic EPMR is a rare but severe complication, sometimes requiring surgery. There are some associated risk factors, including patient- (location, diameter, and presence of fibrosis) and procedure-related factors. Early recognition and timely treatment are crucial for its management.

CASE SUMMARY

We report a case in which delayed perforation with peritonitis was treated using endoscopic closure. A 54-year-old man was diagnosed with a 30-mm-diameter laterally spreading tumor in the colonic hepatic curvature. Fifteen hours after endoscopic resection, peritonitis caused by delayed perforation occurred and gradually aggravated. Conservative treatment was ineffective and no obvious perforation was observed. After timely endoscopic closure, the patient was discharged on postoperative day 4.

CONCLUSION

In occasion of localized peritonitis aggravating without macroscopic perforation, endoscopic closure is an effective treatment for delayed perforation with stable vital signs in the early stage.

[Verification of clinical applicability of the non-special perioperative administration for enhanced recovery after surgery of gastric cancer patients: a Chinese single-center observational report]

Objective: To verify clinical applicability of the non-special perioperative administration for enhanced recovery after surgery (ERAS) proposed by Japanese scholars in Chinese gastric cancer patients. Methods: The main measures of the non-special perioperative administration for ERAS are as follows: (1) discussion of multiple disciplinary team before surgery; (2) rehabilitation education for patients; (3) no routine bowel preparation before surgery; (4) placement of nasogastric tube for decompression routinely before operation and removal as early as 24 hours after surgery; (5) appropriate rehydration; (6) antibiotic prophylaxis before surgery; (7) place abdominal drainage tubes when necessary; (8) epidural patient-controlled analgesia and oral medication for postoperative pain management; (9) start low-molecular-weight heparin injection 48h after surgery and ambulation every day to prevent deep vein thrombosis; (10) postoperative dietary management and supplement with parenteral nutrition intermittently; (11) remove Foley catheter about 24 hours after surgery. A retrospective cohort study was performed, including 203 patients undergoing radical gastrectomy at Department of Gastroenterology, Tianjin Medical University Cancer Institute and Hospital from January 2017 to December 2018. Inclusion criteria were patients who were ≤75 years old without distant metastasis by preoperative examination, were diagnosed as gastric adenocarcinoma by postoperative histopathology and had complete clinicopathological and follow-up data. Patients with history of other malignancies and gastrectomy, extensive implantation of the abdominal cavity or malignant ascites by intraoperative exploration, death within 1 month after surgery, and residual gastric cancer were excluded. The perioperative management methods were chosen by patients. There were 123 patients who followed non-special perioperative administration for ERAS (non-special preparation group) and 80 patients who underwent traditional perioperative management (traditional method group). The primary outcomes (postoperative hospital stay, time to the first flatus, time to the first fluid diet, time to the first ambulatory activity, morbidity of postoperative complication, mortality, and readmission rate) and secondary outcomes (operative time, intraoperative blood loss and postoperative pain score) were compared between the two groups. Results: Compared to the traditional method group, the non-special preparation group had shorter time to the first flatus [(3.6±1.1) days vs. (4.8±1.4) days, t=3.134, P=0.003], shorter time to the first liquid diet [(2.6±0.9) days vs. (5.5±1.6) days, t=15.105, P<0.001], shorter time to the first ambulatory activity [(1.9±0.5) days vs. (4.1±1.1) days, t=8.543, P<0.001] and shorter postoperative hospital stay [(9.6±2.3) days vs. (12.9±2.3) days, t=5.020, P<0.001]. Besides, incidences of pancreatic leakage [6.5% (8/123) vs. 16.3% (13/80), χ(2)=4.964, P=0.026], lymphatic leakage [1.6% (2/123) vs. 13.8% (11/80), χ(2)=11.887, P=0.001], peritoneal effusion [2.4% (3/123) vs. 10.0% (8/80), χ(2)=4.032, P=0.045], and gastroparesis [0.8% (1/123) vs. 7.5% (6/80), χ(2)=4.657, P=0.031] in the non-special preparation group were significantly lower. The overall morbidity of postoperative complications and incidences of pulmonary infection and intestinal adhesion were not significantly different between the two groups (all P>0.05). As for the secondary outcomes, compared to the traditional method group, the non-special preparation group had less intraoperative blood loss [(80.4±24.4) ml vs. (100.5±19.4) ml, t=3.134, P=0.003] and lower postoperative pain score [postoperative day 1: (4.4±0.3) vs. (5.3±0.8), t=2.504, P=0.037],while the difference in operative time was not significant (P>0.05). Conclusion: The non-special perioperative administration for ERAS proposed by Japanese scholars is effective and safe, which has certain clinical applicability and value for Chinese patients with gastric cancer.

Tuning electronic and optical properties of monolayer PdSe2 by introducing defects: first-principles calculations

Based on the density functional theory, the electronic and optical properties of pristine monolayer PdSe2 with Pd or Se vacancy-defect are investigated. Our results show that the Se defect is energetically more favorable than that of Pd defect. The band gap reduces, and some new midgap states appear after the Pd or Se defects are introduced. In terms of the optical properties, the prominent anisotropic characters are remained. The obvious new peaks of the dielectric constant appear after introducing defects. The light absorption in the visible energy range expands based on the appearance of the midgap states induced by the Pd or Se defects. The changes of the refractive index and reflectivity are similar with those of the dielectric constants and the light absorption. The energy loss spectrum of the PdSe2 with Pd or Se defects is obviously different, which can be used to identify different defects in PdSe2. These findings provide effective strategies to tune electronic and optical properties of monolayer PdSe2 by introducing defects.

Endoscopic resection of the pancreatic tail and subsequent wound healing mechanisms in a porcine model

BACKGROUND

Laparoscopic resection of the pancreatic body and tail is the predominant methodology to remove lesions in these locations; its safety and surgical planning are relatively mature, but it remains a complex and high-precision surgical operation, requiring abundant experience and skills in laparoscopic surgery, with a 10% rate of complications.

AIM

To verify the feasibility and safety, as well as to examine the complications of endoscopic pancreatectomy and healing mechanisms of pancreatic wounds after endoscopic resection.

METHODS

Transgastric endoscopic resections of varying sizes of pancreases were performed in 15 healthy Bama miniature pigs. The technical success rate, the incidence of serious complications, and the survival of the animals were studied. The healing of the wounds was evaluated by sacrificing the animals at various time points. Finally, the expression of transforming growth factor-β1 and Smad3/Smad7 in the surgical site was examined by immunohistochemistry to explore the role of these factors in wound healing of the pancreas.

RESULTS

Partial and total resections were successfully performed in two groups of animals, respectively. The technical success rate and the survival rate of the pigs were both 100%. We obtained 12 pancreatic tissue samples by endoscopic resection. The pancreatic wounds were closed with metal clips in one group and the wounds healed well by forming scars. There was a small amount of pancreatic leakage in the other group, but it can be fully encapsulated. The level of transforming growth factor-β1 (TGF-β1) in the wounds increased during the inflammatory and fibrous hyperplasia phases, and decreased in the scar phase. The expression of Smad3 paralleled that of TGF-β1, while the expression of Smad7 had an inverse relationship with the expression of TGF-β1.

CONCLUSION

Purely transgastric endoscopic resection of the pancreas is a safe, effective, and feasible procedure, but the incidence of pancreatic leakage in total pancreatic tail resection is high. The expression of TGF-β1 and Smad3/Samd7 is related to the progression of pancreatic wound healing.

Circular RNA circ-LDLRAD3 as a biomarker in diagnosis of pancreatic cancer

AIM

To analyze the diagnostic value of a circular RNA (circRNA), circ-LDLRAD3, in pancreatic cancer.

METHODS

Expression levels of circ-LDLRAD3 were tested in both cells and clinical samples; the latter included 30 paired pancreatic cancer tissues and adjacent non-tumorous tissues, 31 plasma samples from patients with pancreatic cancer, and 31 plasma samples from healthy volunteers. Real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) was performed to measure expression levels of circ-LDLRAD3 in cells and clinical samples; then, the relationship between clinicopathological factors of patient samples and expression of circ-LDLRAD3 in pancreatic cancer was analyzed. The diagnostic value of circ-LDLRAD3 was verified by receiver operating characteristic (ROC) curve analysis.

RESULTS

Circ-LDLRAD3 was up-regulated in pancreatic cancer cell lines (P < 0.01), pancreatic cancer tissues (P < 0.01), and plasma samples from patients with pancreatic cancer (P < 0.01). High expression of circ-LDLRAD3 was significantly associated with venous invasion, lymphatic invasion, and metastasis. The area under the ROC curve of circ-LDLRAD3 alone or combination with CA19-9 was 0.67 and 0.87, respectively, with a sensitivity and specificity of 0.5738 (alone) and 0.7049 (alone), and 0.8033 (combination) and 0.9355 (combination), respectively.

CONCLUSION

These data suggest that circ-LDLRAD3 may be a biomarker in the diagnosis of pancreatic cancer.

Is the Stella™ 5L system an effective cold sterilization technique for needle-based confocal miniprobes?

Background and Objective:

Needle-based confocal laser endomicroscopy (nCLE) under endoscopic ultrasound guidance is a newly developed imaging technique for pancreatic lesions and lymph nodes, enabling a subcellular level of resolution. The confocal miniprobe is an invasive instrument designed to be reused up to 10 times. Therefore, a method that ensures the complete elimination of microbial contaminants on the device is necessary. We studied the bactericidal efficacy of the Stella™ system, which purports to achieve this objective.

Materials and Methods:

The surfaces of three nCLE miniprobes were contaminated with suspensions of Bacillus atrophaeus (ATCC9372). One probe was randomly selected to count the bacterial load on the surface. The other two probes were manually cleaned and rinsed. One probe was randomly selected to count bacteria on the surface, and the other probe was sterilized using the Stella™ 5L endoscopic sterilization system before obtaining the bacterial count. The process was repeated for 20 cycles to evaluate the microbicidal efficacy of the Stella™ 5L endoscopic sterilization system. These miniprobes were immersed in the Stella Fuse disinfectant for 72 h. After the 72 h of immersion, the weight loss of probes was determined using a high precision electronic scale to examine corrosion following disinfection. The change in image quality was evaluated by an endoscopist.

Results:

From an initial contamination level of 4.48 × 10⁶ ± 1.57 × 10⁶ cfu/mL on the surface of the probes, the bacterial count was reduced to 4.25 × 10² ± 1.95 × 10² cfu/mL after manual cleaning (including enzyme washing), and no microorganisms were recovered after 20 cycles with the Stella™ 5L system. The probe weights before and after 72 h of immersion were 45.769 (45.768–45.771) g and 45.762 (45.752–45.768) g, respectively. No change in image quality was observed.

Conclusion:

This study shows that the Stella™ 5L system is capable of the complete elimination of microorganism contamination in a short period and avoids the toxicity of typical disinfectants. It is a safe, cheap, and efficient sterilization approach that provides a new option for nCLE miniprobe sterilization.

Effects of premedication with Pronase for endoscopic ultrasound of the stomach: A randomized controlled trial

AIM

To analyze the effects of premedication with Pronase for endoscopic ultrasound (EUS) examination of the stomach.

METHODS

This was a prospective, randomized and controlled clinical study. All patients were randomly assigned to either the Pronase group or placebo group. The pretreatment solution was a mixed solution of 20000 U of Pronase and 60 mL sodium bicarbonate solution in the Pronase group, while an equal amount of sodium bicarbonate solution was administered to the placebo group. All operators, image evaluators and experimental recorders in EUS did not participate in the preparation and allocation of pretreatment solution. Two blinded investigators assessed the obscurity scores for the EUS images according to the size of artifacts (including ultrasound images of the gastric cavity and the gastric wall). Differences in imaging quality, the duration of examination and the usage of physiological saline during the examination process between the Pronase group and the control group were compared.

RESULTS

No differences existed in patient demographics between the two groups. For the gastric cavity, the Pronase group had significantly lower mean obscurity scores than the placebo group (1.0476 ± 0.77 vs 1.6129 ± 0.96, respectively, P = 0.000). The mean obscurity scores for the gastric mucosal surface were significantly lower in the Pronase group than the placebo group (1.2063 ± 0.90 vs 1.7581 ± 0.84, respectively, P = 0.001). The average EUS procedure duration for the Pronase group was 11.60 ± 3.32 min, which was significantly shorter than that of the placebo group (13.13 ± 3.81 min, P = 0.007). Less saline was used in the Pronase group than the placebo group, and the difference was significant (417.94 ± 121.38 mL vs 467.42 ± 104.52 mL, respectively, P = 0.016).

CONCLUSION

The group that had Pronase premedication prior to the EUS examination had clearer images than the placebo group. With Pronase premedication, the examination time was shorter, and the amount of saline used during the EUS examination was less.

Expression of Ras-related protein 25 predicts chemotherapy resistance and prognosis in advanced non-small cell lung cancer

Ras-related protein 25 (Rab25) is involved in many human malignancies. However, its role in chemotherapy response and prognosis in advanced non-small cell lung cancer (NSCLC) remains unknown. Therefore, we investigated the relationship between Rab25 and chemotherapy sensitivity and prognosis in NSCLC. Rab25 expression was assessed using immunohistochemistry in 324 advanced NSCLC patients. Its correlations with clinical features were analyzed. Sensitivity to cisplatin (DDP) was compared between DDP-sensitive A549 and DDP-resistant A549/DDP cells. Furthermore, small interfering RNA (siRNA) targeting Rab25 was used for in vitro experiments. Patients with positive Rab25 expression had a significantly lower chemotherapy response rate (P = 0.004) and poorer overall survival (OS, P = 0.0012) than those with negative Rab25 expression. Multivariate analysis indicated that Rab25 expression was an independent prognostic factor for OS (P = 0.016). Moreover, Rab25 expression was significantly higher in A549/DDP cells than in A549 cells. Knockdown of Rab25 by siRNA suppressed cell migration and invasion. Cisplatin resistance in A549/DDP cells was also partially reversed by Rab25 silencing. Rab25 expression is a potential prognostic index for advanced NSCLC patients and its inhibition may improve chemosensitization in NSCLC treatment.

Stent displacement in endoscopic pancreatic pseudocyst drainage and endoscopic management

A pancreatic pseudocyst (PPC) is a collection of pancreatic fluid enclosed by a non-epithelialized, fibrous or granulomatous wall. Endoscopic pancreatic pseudocyst drainage (PPD) has been widely used clinically to treat PPCs. The success and complications of endoscopic PPD are comparable with surgical interventions. Stent displacement is a rare complication after endoscopic PPD. Almost all the complications of endoscopic PPD have been managed surgically, and there is rare report involving the endoscopic treatment of intraperitoneal stent displacement. We report here a case of stent displacement after endoscopic ultrasound- and fluoroscopy-guided PPD in a 41-year-old female patient with a PPC in the tail of the pancreas. The endoscopic treatment was successfully performed to remove the displaced stent. The clinical course of the patient was unremarkable. The cyst had significantly reduced and disappeared by 12 wk. We found that both endoscopic ultrasound and fluoroscopy should be used during endoscopic PPD to avoid stent displacement. The displaced stent can be successfully treated by endoscopic removal.

MicroRNA repertoire for functional genome research in tilapia identified by deep sequencing

The Nile tilapia (Oreochromis niloticus; Cichlidae) is an economically important species in aquaculture and occupies a prominent position in the aquaculture industry. MicroRNAs (miRNAs) are a class of noncoding RNAs that post-transcriptionally regulate gene expression involved in diverse biological and metabolic processes. To increase the repertoire of miRNAs characterized in tilapia, we used the Illumina/Solexa sequencing technology to sequence a small RNA library using pooled RNA sample isolated from the different developmental stages of tilapia. Bioinformatic analyses suggest that 197 conserved and 27 novel miRNAs are expressed in tilapia. Sequence alignments indicate that all tested miRNAs and miRNAs* are highly conserved across many species. In addition, we characterized the tissue expression patterns of five miRNAs using real-time quantitative PCR. We found that miR-1/206, miR-7/9, and miR-122 is abundantly expressed in muscle, brain, and liver, respectively, implying a potential role in the regulation of tissue differentiation or the maintenance of tissue identity. Overall, our results expand the number of tilapia miRNAs, and the discovery of miRNAs in tilapia genome contributes to a better understanding the role of miRNAs in regulating diverse biological processes.

miR-206 regulates the growth of the teleost tilapia (Oreochromis niloticus) through the modulation of IGF-1 gene expression

MicroRNAs (miRNAs) are ~22-nucleotide noncoding RNAs that play a crucial role in regulating muscle development. Our previous study shows that miR-206 is specifically expressed in tilapia skeletal muscle, and exhibits a dynamic expression pattern at different developmental stages. Here, we reveal that miR-206 emerges as a crucial regulator of tilapia growth. miR-206 loss of function leads to the acceleration of tilapia growth. IGF-1 is identified as the target gene of miR-206. miR-206 directly changes IGF-1 expression by targeting its 3' UTR, and inhibition of miR-206 substantially increases the IGF-1 mRNA level in vivo. Thus, miR-206 could be developed as a molecular marker to assist fish breeding.

miR-203b: a novel regulator of MyoD expression in tilapia skeletal muscle

MyoD is one of the helix-loop-helix proteins regulating muscle-specific gene expression in tilapia. Tight regulation of MyoD protein level is necessary for the precise regulation of skeletal muscle development. MicroRNAs (miRNAs) are a class of regulatory RNAs that post-transcriptionally regulate gene expression. Increasing evidences have suggested that miRNAs play an important role in regulating skeletal muscle development. We reasoned that MyoD expression may be regulated by miRNAs. Bioinformatics prediction identify a putative miR-203b target site in the 3’-UTR of MyoD gene. Interestingly, miR-203b expression is negatively correlated is negatively correlated with MyoD expression. miR-203b suppression leads to a significant increase in MyoD expression, thereby activating MyoD downstream gene. 3’-UTR luciferase reporter assay further verifies the direct interaction between miR-203b and MyoD. Taken together, our studies reveal a novel molecular mechanism in which miRNA participates in transcriptional circuits that regulates gene expression in tilapia skeletal muscle.

The research strategies for probing the function of long noncoding RNAs

Long noncoding RNAs (lncRNAs) represent a new frontier in molecular genetics and molecular biology. They have a tremendous potential for advancing our comprehensive understanding of biological processes in huma n health and disease. The transcripts of lncRNAs are easy to find, but sorting out what they do remains the biggest challenge in lncRNAs' research field. In the paper, we highlight recent progress regarding the methods to explore the roles of lncRNAs.

Association between polymorphisms of interleukin-1B and interleukin-1 receptor antagonist genes and host susceptibility to gastric cancer

AIM: To explore the genotype frequencies of polymorphisms in the interleukin-1B (IL-1B) gene promoter region -31, -511 and +3 954 loci and interleukin-1 receptor antagonist gene (IL-1RN) variable number of tandem repeat (VNTR) in gastric cancer cases and cancer-free controls in a Chinese population, and to evaluate the association between polymorphisms of IL-1B and IL-1RN genes and host susceptibility to gastric cancer.

METHODS: Genotypes were determined by a modified PCR-restriction fragment length polymorphism (PCR-RFLP) approach in 285 histologically-confirmed gastric cancer patients and 265 age-, sex- and residence area frequency-matched cancer-free controls in a Chinese population.

RESULTS: The genotype frequencies of IL-1B C-31T polymorphism were 21.8% for CC, 48.6% for CT and 29.6% for TT among gastric cancer patients, and 27.9%, 48.8% and 23.3% among control subjects (P = 0.203). Similarly, the genotype frequencies of IL-1B T-511C polymorphisms were 18.2% for TT, 56.5% for CT, 25.3% for CC among patients and 24.9%, 52.5%, 22.3% among controls (P = 0.184). Multivariate logistic regression analyses revealed that the risks associated with the IL-1B variant genotypes were 1.75 (95%CI = 1.08-2.85) for -31TT and 1.63 (95%CI = 0.98-2.73) for -511CC, respectively, compared with their wild-type homozygotes. Furthermore, we found a greater increased risk in individuals with both H. pylori nfection and the variant genotypes (adjusted OR 2.14, 95%CI = 1.13-4.06 for -31TT; adjusted OR 2.00, 95%CI = 1.02-3.89 for -511CC), which was consistent with the biological effects of IL-1β. No significant association was observed between polymorphisms of IL-1RN gene and IL-1B gene +3 954 locus and gastric cancer risk.

CONCLUSION: The two IL-1B polymorphisms within promoter region may contribute to the risk of developing gastric cancer in our Chinese population, especially in individuals with H. pylori nfection.

Protein fold recognition through application of residual dipolar coupling data

Residual dipolar coupling (RDC) represents one of the most exciting emerging NMR techniques for studying protein structures. However, solving a protein structure using RDC data alone is a highly challenging problem as it often requires that the starting structure model be close to the actual structure of a protein, for the structure calculation procedure to be effective. We report in this paper a computer program, RDC-PROSPECT, for identification of a structural homolog or analog of a target protein in PDB, which best matches the 15N-1H RDC data of the protein recorded in a single ordering medium. The identified structural homolog/analog can then be used as a starting model for RDC-based structure calculation. Since RDC-PROSPECT uses only RDC data and predicted secondary structure information, its performance is virtually independent of sequence similarity between a target protein and its structural homolog/analog, making it applicable to protein targets out of the scope of current protein threading techniques. We have tested RDC-PROSPECT on all 15N-1H RDC data (representing 33 proteins) available in the BMRB database and the literature. The program correctly identified the structural folds for approximately 80% of the target proteins, significantly better than previously reported results, and achieved an average alignment accuracy of 97.9% residues within 4-residue shift. Through a careful algorithmic design, RDC-PROSPECT is at least one order of magnitude faster than previously reported algorithms for principal alignment frame search, making our algorithm fast enough for large-scale applications.

Effect of alpha interferon on the hepatitis C virus replicon

Chronic hepatitis C virus (HCV) infections can be cured only in a fraction of patients treated with alpha interferon (IFN-alpha) and ribavirin combination therapy. The mechanism of the IFN-alpha response against HCV is not understood, but evidence for a role for viral nonstructural protein 5A (NS5A) in IFN resistance has been provided. To elucidate the mechanism by which NS5A and possibly other viral proteins inhibit the cellular antiviral program, we have constructed a subgenomic replicon from a known infectious HCV clone and demonstrated that it has an approximately 1,000-fold-higher transduction efficiency than previously used subgenomes. We found that IFN-alpha reduced replication of HCV subgenomic replicons approximately 10-fold. The estimated half-life of viral RNA in the presence of the cytokine was about 12 h. HCV replication was sensitive to IFN-alpha independently of whether the replicon expressed an NS5A protein associated with sensitivity or resistance to the cytokine. Furthermore, our results indicated that HCV replicons can persist in Huh7 cells in the presence of high concentrations of IFN-alpha. Finally, under our conditions, selection for IFN-alpha-resistant variants did not occur.

Does a cdc2 kinase-like recognition motif on the core protein of hepadnaviruses regulate assembly and disintegration of capsids?

Hepadnaviruses are enveloped viruses, each with a DNA genome packaged in an icosahedral nucleocapsid, which is the site of viral DNA synthesis. In the presence of envelope proteins, DNA-containing nucleocapsids are assembled into virions and secreted, but in the absence of these proteins, nucleocapsids deliver viral DNA into the cell nucleus. Presumably, this step is identical to the delivery of viral DNA during the initiation of an infection. Unfortunately, the mechanisms triggering the disintegration of subviral core particles and delivery of viral DNA into the nucleus are not yet understood. We now report the identification of a sequence motif resembling a serine- or threonine-proline kinase recognition site in the core protein at a location that is required for the assembly of core polypeptides into capsids. Using duck hepatitis B virus, we demonstrated that mutations at this sequence motif can have profound consequences for RNA packaging, DNA replication, and core protein stability. Furthermore, we found a mutant with a conditional phenotype that depended on the cell type used for virus replication. Our results support the hypothesis predicting that this motif plays a role in assembly and disassembly of viral capsids.

Expression of mouse apolipoprotein SAA1.1 in CE/J mice: isoform-specific effects on amyloidogenesis

Amyloid A (AA) amyloid deposition in mice is dependent upon isoform-specific effects of the serum amyloid A (SAA) protein. In type A mice, SAA1.1 and SAA2.1 are the major apolipoprotein-SAA isoforms found on high-density lipoproteins. During inflammation, both isoforms are increased 1000-fold, but only SAA1.1 is selectively deposited into amyloid fibrils. Previous studies showed that the CE/J mouse strain is resistant to amyloid induction. This resistance is not due to a deficiency in SAA synthesis, but is probably related to the unusual SAA isoform present. The CE/J mouse has a single acute-phase SAA protein (SAA2.2), which is a composite of the SAA1.1 and SAA2.1, with an amino terminus similar to the nonamyloidogenic SAA2.1. Recently, genetic experiments suggested that the SAA2.2 isoform might provide protection from amyloid deposition. To determine the amyloidogenic potential of the CE/J mouse, we generated SAA adenoviral vectors to express the various isoforms in vitro and in vivo. Purified recombinant SAA proteins demonstrated that SAA1.1 was fibrillogenic in vitro, whereas SAA2.2 was unable to form fibrils. Incubation of increasing concentrations of the nonamyloidogenic SAA2.2 protein with the amyloidogenic SAA1.1 did not inhibit the fibrillogenic nature of SAA1.1, or alter its ability to form extensive fibrils. Injection of the mouse SAA1.1 or SAA2.2 adenoviral vectors into mice resulted in isoform-specific expression of the SAA proteins. Amyloid induction after viral expression of the SAA1.1 protein resulted in the deposition of amyloid fibrils in the CE/J mouse, whereas SAA2.2 expression had no effect. Similar expression of the SAA2.2 protein in C57BL/6 mice did not alter amyloid deposition. These data demonstrate that the failure of the CE/J mouse to deposit amyloid is due to the structural inability of the SAA2.2 to form amyloid fibrils. This mouse provides a unique system to test the amyloidogenic potential of altered SAA proteins and to determine the important structural features of the protein.

Combination therapy with lamivudine and adenovirus causes transient suppression of chronic woodchuck hepatitis virus infections

Treatment of hepatitis B virus carriers with the nucleoside analog lamivudine suppresses virus replication. However, rather than completely eliminating the virus, long-term treatment often ends in the outgrowth of drug-resistant variants. Using woodchucks chronically infected with woodchuck hepatitis virus (WHV), we investigated the consequences of combining lamivudine treatment with immunotherapy mediated by an adenovirus superinfection. Eight infected woodchucks were treated with lamivudine and four were infected with approximately 10(13) particles of an adenovirus type 5 vector expressing beta-galactosidase. Serum samples and liver biopsies collected following the combination therapy revealed a 10- to 20-fold reduction in DNA replication intermediates in three of four woodchucks at 2 weeks after adenovirus infection. At the same time, covalently closed circular DNA (cccDNA) and viral mRNA levels both declined about two- to threefold in those woodchucks, while mRNA levels for gamma interferon and tumor necrosis factor alpha as well as for the T-cell markers CD4 and CD8 were elevated about twofold. Recovery from adenovirus infection was marked by elevation of sorbitol dehydrogenase, a marker for hepatocyte necrosis, as well as an 8- to 10-fold increase in expression of proliferating cell nuclear antigen, a marker for DNA synthesis, indicating significant hepatocyte turnover. The fact that replicative DNA levels declined more than cccDNA and mRNA levels following adenovirus infection suggests that the former decline either was cytokine induced or reflects instability of replicative DNA in regenerating hepatocytes. Virus titers in all four woodchucks were only transiently suppressed, suggesting that the effect of combination therapy is transient and, at least under the conditions used, does not cure chronic WHV infections.

Increased serum amyloid a levels reflect colitis severity and precede amyloid formation in IL-2 knockout mice

The lack of sensitive and relatively non-invasive measures has hampered monitoring the clinical course of spontaneously developing colitis in IL-2-deficient (-/-) mice. We selected (i) to study the correlation of the acute phase plasma proteins serum amyloid A (SAA) and serum amyloid P component (SAP) levels with colonic disease and (ii) to characterize the amyloidosis in the IL-2(-/-)animals. IL-2(-/-)mice exhibited increasing severity of gross intestinal inflammation with age, confined to the distal colon. Histologically, the colonic disease score increased serially in IL-2(-/-)animals. Wild-type mice showed no activity, while 16-week-old IL-2(+/-)animals had minimal colitis with small ulcers and lamina propria inflammatory infiltrate. Periportal hepatitis was present and positive Congo red staining indicated amyloidosis of the liver and spleen in 16 week IL-2(-/-)mice. SAA immunostaining in the liver and spleen was increased in the 8 week and 16 week IL-2(-/-)and 16 week IL-2(+/-)animals indicating AA amyloid deposits. Plasma SAA and SAP levels were markedly elevated, and generally preceded the onset of colitis and reflected its severity. Northern analysis showed markedly increased SAA expression in the liver and intestine of IL-2(-/-)and intestine of IL-2(+/-)16-week-old animals. Increased intestinal expression of SAA3 (lamina propria macrophages) indicates local inflammation in IL-2(+/-)animals at 16 weeks. Treatment of 3-week-old animals with systemic IL-2 or IL-1 receptor antagonist (IL-1ra) delayed inflammation, postponed the increase in SAA levels and minimized disease onset. These results further demonstrate that IL-2 plays a significant role in normal immune responses in the body and that plasma SAA levels both reflect colonic disease severity and may indicate subclinical disease in both IL-2(-/-)and IL-2(+/-)mice. Furthermore. The mechanism of IL-2-deficient induced colitis appears to be mediated in part through the increase in IL-1. In addition, the IL-2(-/-)mouse of spontaneous enterocolitis may provide a unique system for studying spontaneously developing AA amyloidosis.

Amyloid formation in the rat: adenoviral expression of mouse serum amyloid A proteins

Serum amyloid A (SAA) proteins are acute-phase apolipoproteins that are associated with high-density lipoprotein (HDL) particles: SAA proteins are precursors to secondary amyloid fibril proteins and under certain conditions of chronic or recurrent inflammation these proteins are deposited as amyloid fibrils. Of two isotypes found in mouse, SAA1.1 and SAA2.1, only SAA1.1 is deposited into amyloid. The CE/J mouse is unique, in that the only isoform identified is a hybrid between SAA1.1 and SAA2.1 and the mouse does not show amyloid deposition. In the rat, a deletion in the SAA1/SAA2 gene is associated with the absence of protein in the plasma and subsequently no amyloid deposition is detected. We have generated adenoviral vectors to study the expression of SAA proteins on HDL metabolism and amyloid formation. Injection of SAA viruses into rats resulted in expression of the mouse SAA proteins in the plasma with specific association of the SAA with HDL particles. The induction of SAA proteins was comparable to that seen in mice presented with the inflammatory agent, bacterial lipopolysaccharide (LPS). Adenoviral induced SAA levels were maintained for up to several weeks without a significant decrease in SAA expression. Injection of rats with the mouse SAA1.1 adenoviral vector, followed by amyloid enhancing factor (AEF) and silver nitrate resulted in the deposition of amyloid fibrils in the spleen. After 2 weeks, amyloid could be detected in other tissues, including the heart, liver, kidneys and lungs. When animals were injected with null or the SAA2.2 virus no amyloid was detected. These studies demonstrate that the inability of the rat to develop AA amyloid is due to the lack of synthesizing an amyloidogenic SAA protein. Furthermore, the expression of the adenoviral SAA protein from the liver and incorporation onto HDL particles further supports the hypothesis that AA amyloid is derived from circulating SAA protein. The ease of use of the adenoviral vectors and the rat provide an excellent model to study the function of SAA proteins.

Apoptosis and regeneration of hepatocytes during recovery from transient hepadnavirus infections

It is well known that hepatitis B virus infections can be transient or chronic, but the basis for this dichotomy is not known. To gain insight into the mechanism responsible for the clearance of hepadnavirus infections, we have performed a molecular and histologic analysis of liver tissues obtained from transiently infected woodchucks during the critical phase of the recovery period. We found as expected that clearance from transient infections occurred subsequent to the appearance of CD4(+) and CD8(+) T cells and the production of interferon gamma and tumor necrosis factor alpha in the infected liver. These events were accompanied by a significant increase in apoptosis and regeneration of hepatocytes. Surprisingly, however, accumulation of virus-free hepatocytes was delayed for several weeks following this initial influx of lymphocytes. In addition, we observed that chronically infected animals can exhibit levels of T-cell accumulation, cytokine expression, and apoptosis that are comparable with those observed during the initial phase of transient infections. Our results are most consistent with a model for recovery predicting replacement of infected hepatocytes with regenerated cells, which by unknown mechanisms remain protected from reinfection in animals that can be cured.

Aberrant expression of a cytokeratin in a subset of hepatocytes during chronic WHV infection

Chronic infection of woodchucks with woodchuck hepatitis virus (WHV) invariably leads, within 2-4 years, to the appearance of hepatocellular carcinoma (HCC). HCC is preceded by an extended period of chronic liver damage, probably resulting from the immune response to viral antigens. It may be that infection itself also induces changes in the hepatocyte population. To begin to identify some of the changes in the liver prior to the appearance of HCC, monoclonal antibodies (MAbs) were generated from mice immunized with hepatocytes from a woodchuck chronically infected with WHV or with a tumor lysate. Immunofluorescence microscopy was used to select MAbs that reacted with host markers whose patterns of expression would distinguish chronically infected from uninfected liver or from liver tumors. One of these MAbs (2F2) reacted strongly with a subset of hepatocytes in chronically infected liver; a similar staining pattern was not detected in uninfected or transiently infected liver. Evidence is presented that this strong staining reaction reflects the overexpression or accumulation of the hepatocyte-specific intermediate filament protein, cytokeratin K18, a protein previously implicated in cryptogenic cirrhosis of the liver in humans (Ku, N. O. , Wright, T. L., Terrault, N. A., Gish, R., and Omary, M. B. J. Clin. Invest. 99: 19-23, 1997). Double immunofluorescent staining with antibodies to K18 and M-envelope protein of WHV suggested that strong reactivity to K18 was limited to cells expressing high levels of one or both of the large viral-envelope proteins, M and L; however, high expression of these viral proteins was not always associated with a strong K18 staining reaction.

Cloning and expression of a cDNA encoding the large subunit of duck replication factor C

A cDNA encoding an avian homologue of the large subunit of replication factor C (RFC-L) has been cloned from a duck liver cDNA expression library prepared in bacteriophage lambda. The full length cDNA encodes a protein with a predicted size of approximately 130 kDa, consistent with the size of the polypeptide detected in duck liver. The duck RFC-L amino acid sequence shares 66.4% and 68.4% identity with mouse and human RFC-L proteins, respectively. We identified a 4kb RFC-L mRNA expressed in most duck tissues.

Inducible expression of human hepatitis B virus (HBV) in stably transfected hepatoblastoma cells: a novel system for screening potential inhibitors of HBV replication

We report the development and isolation of a cell line, termed HepAD38, that replicates human hepatitis B virus (HBV) under conditions that can be regulated with tetracycline. In the presence of the antibiotic, this cell line is free of virus due to the repression of pregenomic (pg) RNA synthesis. Upon removal of tetracycline from the culture medium, the cells express viral pg RNA, accumulate subviral particles in the cytoplasm that contain DNA intermediates characteristic of viral replication, and secrete virus-like particles into the supernatant. Since the HepAD38 cell line can produce high levels of HBV DNA, it should be useful for analyses of the viral replication cycle that depend upon viral DNA synthesis in a synchronized fashion. In addition, this cell line has been formatted into a high-throughput, cell-based assay that permits the large-scale screening of diverse compound libraries for new classes of inhibitors of HBV replication.

Monoclonal antibodies to a 55-kilodalton protein present in duck liver inhibit infection of primary duck hepatocytes with duck hepatitis B virus

As an approach to identifying hepatocyte receptors for the avian hepadnavirus duck hepatitis B virus (DHBV), hybridomas were prepared from mice immunized with permissive duck hepatocytes. Monoclonal antibodies (MAbs) were screened for the ability to inhibit binding of DHBV particles to primary duck hepatocytes and to block infection. We identified two MAbs which partially blocked binding and caused marked inhibition of infection of primary duck hepatocytes with DHBV. Lack of cross-reactivity with DHBV envelope proteins suggested that inhibition of infection was due to specific interaction between the antibodies and a host cell surface molecule. Both MAbs immunoprecipitated a 55-kDa protein (p55) expressed in duck liver and several other duck tissues. p55 homologs were also identified in other birds and mammals. We predict from our data that only a small proportion of total cellular p55 molecules are expressed at the surfaces of hepatocytes and that p55 is involved in some early step in the infectious pathway.

Topology of the large envelope protein of duck hepatitis B virus suggests a mechanism for membrane translocation during particle morphogenesis

We have investigated the membrane topology of the large envelope protein of duck hepatitis B virus (DHBV) by protease protection and Western blot analysis, using monoclonal antibodies specific for the pre-S and S regions of the DHBV envelope to characterize protease-resistant polypeptides. These studies showed that DHBV L protein exhibits a mixed membrane topology similar to that of human hepatitis B virus L, with approximately half of the L molecules displaying pre-S on the surface of virus particles and the remainder with pre-S sequestered inside the virus envelope. The C-terminal region of DHBV pre-S was susceptible to protease digestion on all DHBV particle L protein, indicating that this region was externally disposed. DHBV L protein pre-S was entirely cytosolic immediately after synthesis. Our data, therefore, suggested that an intermediate form of the DHBV L molecule exists in mature envelope particles in which L is partially translocated or exists in a translocation-ready conformation. Incubation of virus particles at low pH and 37 degrees C triggered conversion of this intermediate into a fully translocated form. We have proposed a model for pre-S translocation based on our results that invokes the presence of an aqueous pore in the virus envelope, most likely created by oligomerization of transmembrane domains in the S region. The model predicts that pre-S is transported through this pore and that a loop structure is formed because the N terminus remains anchored to the inner face of the membrane. This translocation process occurs during particle morphogenesis and may also be a prerequisite to virus uncoating during infection.

Characterization of serum amyloid A protein mRNA expression and secondary amyloidosis in the domestic duck

Secondary amyloidosis is a common disease of water fowl and is characterized by the deposition of extracellular fibrils of amyloid A (AA) protein in the liver and certain other organs. Neither the normal role of serum amyloid A (SAA), a major acute phase response protein, nor the causes of secondary amyloidosis are well understood. To investigate a possible genetic contribution to disease susceptibility, we cloned and sequenced SAA cDNA derived from livers of domestic ducks. This revealed that the three C-terminal amino acids of SAA are removed during conversion to insoluble AA fibrils. Analysis of SAA cDNA sequences from several animals identified a distinct genetic dimorphism that may be relevant to susceptibility to secondary amyloid disease. The duck genome contained a single copy of the SAA gene that was expressed in liver and lung tissue of ducklings, even in the absence of induction of acute phase response. Genetic analysis of heterozygotes indicated that only one SAA allele is expressed in livers of adult birds. Immunofluorescence staining of livers from adult ducks displaying early symptoms of amyloidosis revealed what appear to be amyloid deposits within hepatocytes that are expressing unusually high amounts of SAA protein. This observation suggests that intracellular deposition of AA may represent an early event during development of secondary amyloidosis in older birds.

[Uses of duck hepatitis B virus polymerase and reverse transcriptase in the evaluation of anti-hepatitis B virus drugs]

The method of DHBV replication complexes (RCs) purification was modified. In order to screen anti-HBV drugs from Chinese medicinal herbs, the inhibitory effects of the extracts of 14 Chinese recipes and herbs, 30 compounds isolated from Chinese herbs on DHBV DNA polymerase (DNAP) and reverse transcriptase (RT) have been studied. The results showed that extracts of Xiao Chai Hu Tang (small Bupleurum decoction) inhibited DHBV DNAP and RT in less extent. Of the 7 herbs, the components of Xiao Chai Hu Tang, the extracts of S. baicalensis and P. ternata potently inhibited DHBV RT, their concentration of reducing enzyme activity by 50% (IC50) was 1.25 and 1.6 mg/ml respectively. Furthermore, it has been proved that S. baicalensis inhibited DHBV DNA replication in ducklings. It also was found the extract of P. cuspidatum inhibited DHBV RT with IC50 of 1.76 mg/ml. Nine of thirty isolated compounds inhibited both DHBV DNAP and RT in less extent under high concentration, while other did not.

[In vitro transformation of Syrian hamster embryo cells by four chemicals]

In this paper, the early passage diploid Syrian hamster embryo (SHE) cells were used as the source of target. Four chemicals were appraised in SHE transformation test to determine whether they were carcinogens or not. They were (1) 2-benzoyl-hydrazono-1,3-diethiolane(BHD) (technical product); (2) isoprothiolane (pure product); (3) isoprothiolane (technical product); (4) benzene-abstracts from coal smoke of coke oven (benzene-abstracts). The results showed that morphological transformation was not observed when cells were not treated or treated with dimethyl sulfoxide, BHD, pure isoprothiolane and the technical product of isoprothiolane. The highest concentration had considerable cytotoxicity. In the groups of positive control (1.0 microgram/ml 3-methyl-cholanthrene, 10.0 micrograms/ml benzo (a) pyrene) and benzene-abstracts, we could observe colonies with random or criss-cross orientation and dense piling-up of cells. According to well known positive criteria, the benzene-abstracts can induce SHE cells morphological transformation. The other three chemicals can not induce SHE cells transformation.