Irisin inhibits neutrophil extracellular traps formation and protects against acute pancreatitis in mice.

INTRODUCTION: Irisin is a newly discovered myokine which links exercise to inflammation and inflammation-related diseases through macrophage regulation. However, the effect of irisin on the activity of inflammation related immune cells (such as neutrophils) has not been clearly described. OBJECTIVES: The objective of our study was to explore the effect of irisin on the neutrophil extracellular traps (NETs) formation. METHODS: Phorbol-12-myristate-13-acetate (PMA) was used to construct a classic neutrophil inflammation model that was used to observe the formation of NETs in vitro. We studied the effect of irisin on NETs formation and its regulation mechanism. Subsequently, acute pancreatitis (AP) was used to verify the protective effect of irisin in vivo, which was an acute aseptic inflammatory response disease model closely related to NETs. RESULTS: Our study found that addition of irisin significantly reduced the formation of NETs via regulation of the P38/MAPK pathway through integrin αVß5, which might be the one of key pathways in NETs formation, and which could theoretically offset the immunoregulatory effect of irisin. Systemic treatment with irisin reduced the severity of tissue damage common in the disease and inhibited the formation of NETs in pancreatic necrotic tissue of two classical AP mouse models. CONCLUSION: The findings confirmed for the first time that irisin could inhibit NETs formation and protect mice from pancreatic injury, which further elucidated the protective effect of exercise on acute inflammatory injury.

Elevated serum HbA1c level, rather than previous history of diabetes, predicts the disease severity and clinical outcomes of acute pancreatitis.

INTRODUCTION: The aim of our study is to explore the value of serum glycosylated hemoglobin A1c (HbA1c) in disease severity and clinical outcomes of acute pancreatitis (AP). RESEARCH DESIGN AND METHODS: Patients with AP were included from January 2013 to December 2020, retrospectively, dividing into normal serum HbA1c level (N-HbA1c) group and high serum HbA1c level (H-HbA1c) group according to the criteria HbA1c <6.5%. We compared patient characteristics, biochemical parameters, disease severity, and clinical outcomes of patients with AP in two groups. Besides, we evaluated the efficacy of serum HbA1c to predict organ failure (OF) in AP patients by receiver operating curve (ROC). RESULTS: We included 441 patients with AP, including 247 patients in N-HbA1c group and 194 patients in H-HbA1c group. Serum HbA1c level was positively correlated with Atlanta classification, systemic inflammatory response syndrome, local complication, and OF (all p<0.05). Ranson, BISAP (bedside index of severity in acute pancreatitis), and CT severity index scores in patients with H-HbA1c were markedly higher than those in patients with N-HbA1c (all p<0.01). ROC showed that the best critical point for predicting the development of OF in AP with serum HbA1c is 7.05% (area under the ROC curve=0.79). Logistic regression analysis showed H-HbA1c was the independent risk factor for the development of OF in AP. Interestingly, in patients with presence history of diabetes and HbA1c <6.5%, the severity of AP was significantly lower than that in H-HbA1c group. Besides, there was no significant difference between with and without history of diabetes in N-HbA1c group. CONCLUSIONS: Generally known, diabetes is closely related to the development of AP, and strict control of blood glucose can improve the related complications. Thus, the level of glycemic control before the onset of AP (HbA1c as an indicator) is the key to poor prognosis of AP, rather than basic history of diabetes. Elevated serum HbA1c level can become the potential indicator for predicting the disease severity of AP.

Elevated serum ferritin levels are associated with severity and prognosis of severe acute pancreatitis: a preliminary cohort study.

BACKGROUND: Serum ferritin (SF), as an acute-phase response protein, is used to reflect the degree of oxidative stress and systemic inflammatory responses. This study was designed to assess the effect of elevated SF levels on the severity of acute pancreatitis (AP). METHODS: From January 2013 to December 2020, 200 consecutive patients with AP were retrospectively reviewed to analyze the relationships among the etiologies of pancreatitis, the severity of the disease and SF levels. The receiver operating characteristic (ROC) curve and logistic regression analysis were used to assess whether elevated SF levels could predict the onset of organ failure in AP. RESULTS: 92 (46%) had high SF levels (> 275 ng/ml). SF levels were not associated with the etiology of AP disease. Among patients with high SF levels, there was a significant increase in the proportion of patients with severe AP (23.1% vs. 76.9%) and a higher proportion of systemic inflammatory response scores (25.9% vs. 44.6%) in comparison to patients with normal SF levels. The area under the ROC curve for SF in predicting persistent organ failure was 0.812 [95% confidence interval 0.721-0.904]. CONCLUSIONS: F concentrations were positively correlated with the severity of AP, and quantitative assessment of SF can predict disease severity and organ failure in patients with AP.

Prediction of the severity of acute pancreatitis using machine learning models.

BACKGROUND: Acute pancreatitis (AP) is the most common pancreatic disease. Predicting the severity of AP is critical for making preventive decisions. However, the performance of existing scoring systems in predicting AP severity was not satisfactory. The purpose of this study was to develop predictive models for the severity of AP using machine learning (ML) algorithms and explore the important predictors that affected the prediction results. METHODS: The data of 441 patients in the Department of Gastroenterology in our hospital were analyzed retrospectively. The demographic data, blood routine and blood biochemical indexes, and the CTSI score were collected to develop five different ML predictive models to predict the severity of AP. The performance of the models was evaluated by the area under the receiver operating characteristic curve (AUC). The important predictors were determined by ranking the feature importance of the predictive factors. RESULTS: Compared to other ML models, the extreme gradient boosting model (XGBoost) showed better performance in predicting severe AP, with an AUC of 0.906, an accuracy of 0.902, a sensitivity of 0.700, a specificity of 0.961, and a F1 score of 0.764. Further analysis showed that the CTSI score, ALB, LDH, and NEUT were the important predictors of the severity of AP. CONCLUSION: The results showed that the XGBoost algorithm can accurately predict the severity of AP, which can provide an assistance for the clinicians to identify severe AP at an early stage.

Machine learning predictive models for acute pancreatitis: A systematic review.

INTRODUCTION: Acute pancreatitis (AP) is a common clinical pancreatic disease. Patients with different severity levels have different clinical outcomes. With the advantages of algorithms, machine learning (ML) has gradually emerged in the field of disease prediction, assisting doctors in decision-making. METHODS: A systematic review was conducted using the PubMed, Web of Science, Scopus, and Embase databases, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Publication time was limited from inception to 29 May 2021. Studies that have used ML to establish predictive tools for AP were eligible for inclusion. Quality assessment of the included studies was conducted in accordance with the IJMEDI checklist. RESULTS: In this systematic review, 24 of 2,913 articles, with a total of 8,327 patients and 47 models, were included. The studies could be divided into five categories: 10 studies (42%) reported severity prediction; 10 studies (42%), complication prediction; 3 studies (13%), mortality prediction; 2 studies (8%), recurrence prediction; and 2 studies (8%), surgery timing prediction. ML showed great accuracy in several prediction tasks. However, most of the included studies were retrospective in nature, conducted at a single centre, based on database data, and lacked external validation. According to the IJMEDI checklist and our scoring criteria, two studies were considered to be of high quality. Most studies had an obvious bias in the quality of data preparation, validation, and deployment dimensions. CONCLUSION: In the prediction tasks for AP, ML has shown great potential in assisting decision-making. However, the existing studies still have some deficiencies in the process of model construction. Future studies need to optimize the deficiencies and further evaluate the comparability of the ML systems and model performance, so as to consequently develop high-quality ML-based models that can be used in clinical practice.

Impact of Fatty Pancreas on Postoperative Pancreatic Fistulae: A Meta-Analysis.

BACKGROUND: Soft pancreas is widely recognized as an important risk factor for the development of postoperative pancreatic fistula (POPF). Although fatty pancreas (FP) has not been formally defined as a cause of pancreatic fistula, existing research has shown that it can increase the incidence of POPF by increasing pancreatic tenderness; therefore, it may be a potential risk factor. This study aimed to discern whether FP was associated with POPF. METHOD: Two reviewers independently performed literature searches from five electronic databases. According to the established inclusion criteria, we extracted necessary data from the studies that met the criteria for further analysis. We pooled the odds ratios (ORs) from individual studies using a random-effects model to investigate the associations between POPF and the prognosis of FP. RESULT: A total of 11 studies involving 2484 individuals were included. The pooled prevalence of POPF was 18% (95% CI: 12-24%). Body mass index (BMI) was associated with a significantly increased risk of POPF (OR=3.55; 95% CI: 1.83, 6.86; P=0.0002; I²=0). FP was obviously associated with the occurrence of POPF (OR=3.75; 95% CI: 1.64, 8.58; P=0.002; I²=78). CONCLUSION: FP is closely associated with the development of POPF, and the early identification of these high-risk patients can help to reduce the incidence of POPF. SYSTEMATIC REVIEW REGISTRATION: The Registration URL link is (https://www.crd.york.ac.uk/PROSPERO/). The ID is "CRD42021265141".

Diabetes aggravates acute pancreatitis possibly via activation of NLRP3 inflammasome in db/db mice.

Clinical studies have confirmed that patients with diabetes had an elevated risk of acute pancreatitis (AP) and diabetes was associated with increased severity and mortality in patients with AP. However, these studies failed to prove a cause-and-effect relationship between diabetes and AP. In the present study, we for the first time have evaluated the effects of diabetes on AP by adopting a type 2 diabetes animal model db/db mice and investigated the possible underlying mechanisms. The results showed that in comparison to wide type (WT) mice, db/db mice showed exacerbated pancreatic and pulmonary injuries, elevated serum amylase and lipase levels, increased myeloperoxidase (MPO) expressions in pancreatic and pulmonary tissues as well as increased apoptotic acinar cells after AP induction. Furthermore, we observed that NLRP3 inflammasome in pancreatic tissues was remarkably activated in db/db mice compared with WT mice. In addition, we also found that diabetes could increase the susceptibility of mice to AP. Taken together, our results indicated that diabetes could predispose and aggravate the disease severity of AP potentially via promoting the activation of NLRP3 inflammasome pathway.

Prevalence and clinical characteristics of fatty pancreas in Yangzhou, China: A cross-sectional study.

OBJECTIVE: The aim of this study was to investigate the prevalence and risk factors of fatty pancreas in Yangzhou, China. METHODS: This was a cross-sectional study. Initially, 2093 subjects were included in the study. After the exclusion of 865 subjects based on incomplete information, a total of 1228 subjects were selected for further analysis. The subjects were stratified into two groups (the fatty pancreas group and the non-fatty pancreas group) based on the results. Anthropometric and biochemical findings were compared between the groups. RESULTS: Among the 2093 study subjects, 56 (2.7%) had fatty pancreas. Overall, 53 out of 1228 subjects were diagnosed with fatty pancreas and included into the fatty pancreas group. Univariate analysis showed significant differences in age and the prevalence of general obesity, central obesity, alcohol consumption, metabolic syndrome and fatty liver between the two groups (all p < 0.01). The fatty pancreas group had higher levels of aspartate aminotransferase, alanine aminotransferase, serum uric acid, fasting blood glucose, total cholesterol, triglycerides and low-density lipoprotein, and lower levels of high-density lipoprotein than did the non-fatty pancreas group (all p < 0.05). Multivariate logistic regression analysis showed that age (p = 0.007), central obesity (p = 0.002) and fatty liver (p = 0.006) were independent risk factors for fatty pancreas, with odds ratios (ORs) of 1.034 (95% confidence interval (CI): 1.009-1.059), 5.364 (95% CI: 1.890-15.227), and 2.666 (95% CI: 1.332-5.338), respectively. CONCLUSION: The prevalence of fatty pancreas in the examined population is approximately 2.7%. Increased age, central obesity and fatty liver disease are independent risk factors for fatty pancreas.

Case report: successful resection of a leiomyoma causing pseudoachalasia at the esophagogastric junction by tunnel endoscopy.

BACKGROUND: Pseudoachalasia is a rare disorder whose presentation strongly resembles idiopathic achalasia. CASE PRESENTATION: Here, we present a case of a 42-year-old female patient with esophageal leiomyoma who was initially diagnosed with achalasia. On endoscopical investigation, however, it became apparent that she had pseudoachalasia as consequence of a leiomyoma at the esophagogastric junction (EGJ). The condition was successfully treated through submucosal tunneling endoscopic resection. CONCLUSION: This case suggests that submucosal tunneling endoscopic resection is a therapeutic u option for the treatment of pseudoachalasia caused by leiomyoma of EGJ.

[Advance in studies on antitumor and immunomodulatory effects of wogonin].

Wogonin is a kind of natural flavonoid compound. According to findings in the latest studies, wogonin shows a wide range of antitumor effects, with the characteristics of multi-pathway, multi-link and multi-target, such as promoting tumor cell apoptosis through ROS or Ca(2+)-mediated signal paths, enhancing tumor cytotoxicity by TNF-α and TRAIL, blocking tumor cell cycle, inhibiting tumor angiogenesis and resisting cancer synergistically with chemotherapeutic drugs. Moreover, Wogonin could enhance body immune function by enhancing immune cell infiltration, regulating the immune cell phenotype and promoting relevant cytokine secretion. In this paper, the authors summarized the advance in studies on wogonin's antitumor and immunomodulatory effects.

Intratumor hypoxia promotes immune tolerance by inducing regulatory T cells via TGF-ß1 in gastric cancer.

Regulatory T cell (Treg)-mediated immunosuppression represents one of the crucial tumor immune evasion mechanisms and is a main obstacle for successful tumor immunotherapy. Hypoxia, a common feature of solid tumors, has been associated with potentiated immunosuppression, decreased therapeutic response, malignant progression and local invasion. Unfortunately, the link between hypoxia and Treg-mediated immune tolerance in gastric cancer remains poorly understood. In our study, Tregs and hypoxia inducible factor-1α were found to be positively correlated with each other and were increased with the tumor progression. A subsequent in vitro study indicated that supernatants derived from gastric cancer cells under hypoxic condition, could induce the expression of Foxp3 via TGF-ß1. These findings confirmed the crucial role of Tregs as a therapeutic target in gastric cancer therapy and provided helpful thoughts for the design of immunotherapy for gastric cancer in the future.

Synchronous vs sequential laparoscopic cholecystectomy for cholecystocholedocholithiasis.

AIM: To compare synchronous laparoscopic cholecystectomy (LC) combined with endoscopic sphincterotomy (EST) and sequential LC combined with EST for treating cholecystocholedocholithiasis. METHODS: A total of 150 patients were included and retrospectively studied. Among these, 70 were selected for the synchronous operation, in which the scheme was endoscopic retrograde cholangiopancreatography combined with EST during LC. The other 80 patients were selected for the sequential operation, in which the scheme involved first cutting the papillary muscle under endoscopy and then performing LC. The indexes in the two groups, including the operation time, the success rate, the incidence of complications, and the length of the hospital stay, were observed. RESULTS: There were no significant differences between the groups in terms of the numbers of patients, sex distribution, age, American Society of Anesthesiologists score, serum bilirubin, γ-glutamyl transpeptidase, mean diameter of common bile duct stones, and previous medical and surgical history (P = 0.54, P = 0.18, P = 0.52, P = 0.22, P = 0.32, P = 0.42, P = 0.68, P = 0.70, P = 0.47 and P = 0.57). There was no significant difference in the surgical operation time between the two groups (112.1 ± 30.8 min vs 104.9 ± 18.2 min). Compared with the sequential operation group, the incidence of pancreatitis was lower (1.4% vs 6.3%), the incidence of hyperamylasemia (1.4% vs 10.0%, P < 0.05) was significantly reduced, and the length of the hospital stay was significantly shortened in the synchronous operation group (3 d vs 4.5 d, P < 0.001). CONCLUSION: For treatment of cholecystocholedocholithiasis, synchronous LC combined with EST reduces incidence of complications, decreases length of hospital stay, simplifies the surgical procedure, and reduces operation time.

A high level of integrin α6 expression in human intrahepatic cholangiocarcinoma cells is associated with a migratory and invasive phenotype.

BACKGROUND: The integrin α6 subunit is part of the integrin α6ß1 and α6ß4 complexes, which are known to mediate the invasion of carcinoma cells. However, the precise role of integrin α6 in intrahepatic cholangiocarcinoma (ICC) has not yet been addressed. METHODS: Twenty cases of ICCs and matched nontumor samples were used to analyze integrin α6 expression by immunohistochemistry. After the expression of integrin α6 was determined by RT-PCR and Western blot in ICC cells, we regulated the expression of integrin α6 in ICC cells with specific vshRNA-integrin α6, and assessed the role of integrin α6 in the proliferation and metastasis/invasion of ICC cells. Finally, the involved mechanisms and clinical significance were further investigated. RESULTS: The expression of integrin α6 in ICC tissues was much higher than that in nontumor samples, and the high level of integrin α6 was detected in ICC cells compared with normal liver cells and HepG2 cells. After the down-regulation of integrin α6 in HCCC-9810 cells, we showed that the ability of ICC cells to metastasize and invade was much decreased in vitro, and cell proliferation was inhibited significantly. Further study indicated high expression of integrin α6 enhanced the activation of ERK1/2 and AKT signals in ICC cells and the inhibition of ERK1/2 down-regulated ICC cell proliferation, while the inhibition of AKT markedly impaired ICC cell metastasis and invasion. Integrin α6 overexpression was significantly correlated with larger tumors, multiple nodular, microvascular/bile duct invasion, and lymphatic metastasis (p < 0.05). The postoperative 5-year overall survival (OS) rate in patients with integrin α6(low) was higher than that of the integrin α6(high) group. CONCLUSIONS: Overexpression of integrin α6 is associated with a migratory and invasive phenotype of ICC, and integrin α6 may be used as molecular target for therapy of ICC.

[Effects of natural killer cells stimulated with immobilized MHC class I chain-related antigen A on activities of dendritic cells].

AIM: To observe the effects of NK cells stimulated with immobilized MHC class I chain-related antigen A (iMICA) on activities of dendritic cells (DCs). METHODS: Firstly fresh allogeneic NK cells, or iMICA-stimulated allogeneic NK cells, and autologous NK cells stimulated with IL-2 or IL-2 and iMICA were co-cultured with immature DCs (iDCs) at the ratio of 5:1 for 24 hours. Frequencies of HLA-DR positive or CD86 positive DCs were detected by flow cytometry. Next autologous NK cells stimulated with iMICA were co-cultured with iDCs at the ratio of 1:5 for 24 hours. Variation of HLA-DR or CD86 expression on dendritic cells was measured. Lastly IFN-γ neutralizing antibody was added into the NK-DCs co-culture system to observe HLA-DR or CD86 expression on DCs. RESULTS: When NK:iDCs ratio was 5:1, both fresh allogeneic and activated autologous NK cells killed iDCs efficiently. iMICA did not synergize this cytotoxicity. However, when NK:iDCs ratio was 1:5, NK cells activated by iMICA promoted HLA-DR and CD86 expression on DCs. IFN-γ antibody down-regulated HLA-DR and CD86 expression on DCs which were co-cultured with iMICA-activated NK cells. CONCLUSION: iMICA is redundant as fresh allogeneic or activated autologous NK cells killed iDCs. However, if numbers of NK cell are less than those of DCs, iMICA can stimulate NK cells to produce IFN-γ for DCs maturation.

[The effect of up-regulation of MHC class I chain-related antigen A expression by dendritic cells on activity of NK cells].

AIM: To observe whether MHC class I chain-related antigen A (MICA) was expressed on monocytes, immature dendritic cells (iDCs), and mature dendritic cells (mDCs), and to study effect of up-regulation of MICA expression by DCs on biologic activity of NK cells. METHODS: MICA expression on monocytes, iDCs, or mDCs stimulated with LPS, TNF-α, CD40L, IL-15 or IFN-α was detected by flow cytometry. Next CD69 expression, degranuation, and IFN-γ production of NK cells stimulated with MICA-positive mDCs were analyzed. Lastly recombinant NKG2D/Fc fusion protein and anti-IL-12 monoclonal antibody was respectively added into culture systems to analyze whether these reagents affected the interaction between DCs and NK cells. RESULTS: MICA was not expressed on monocytes, and expressed on iDCs at low level. LPS, TNF-α, CD40L had no influences on MICA expression on mDCs, but IFN-α, IL-15 up-regulated MICA expression on mDCs. MICA-positive mDCs promoted CD69 expression, IFN-γ production, and killing K562 cells by NK cells. NKG2D/Fc inhibited both cytotcoxicity and IFN-γ secretion, whereas IL-12 antibody only inhibited IFN-γ secretion of NK cells. CONCLUSION: MICA expression on DCs is regulated by relevant factors in microenvironment. DCs with high level of MICA expression can up-regulate biologic activity of NK cells.

[Association of MICA gene polymorphism and serum soluble MICA level with colorectal cancer].

OBJECTIVE: To investigate whether the major histocompatibility complex class I chain-related gene A gene (MICA) polymorphism and serum soluble MICA level were associated with the occurrence and development of colorectal cancer. METHODS: DNA samples from 117 colorectal cancer patients and 113 healthy individuals from Yangzhou in Jiangsu province were genotyped by using the polymerase chain reaction (PCR) and sequence-specific primer (SSP) method and PCR based sequencing. In addition, polymorphism at position 129 was also analyzed by PCR-SSP. Serum levels of soluble MICA were measured by a sandwich ELISA method. RESULTS: Neither the extracellular nor the transmembrane region polymorphisms of MICA gene were associated with the occurrence and the different stages of colorectal cancer. In contrast, the frequency of the methionine residue at position 129 was significantly decreased in the patient group. Soluble MICA levels in sera were increased in the late stages of colorectal cancer. CONCLUSION: Although there was no genetic susceptibility attributed to MICA gene polymorphism with regard to development of colorectal cancer, serum levels of soluble MICA may be a diagnostic marker of advanced stages.

[Correlation of Helicobacter pylori infection with the expression of COX-2 and EGFR and VEGF in human gastric carcinoma].

OBJECTIVE: To investigate the correlation of Helicobactor pylori (Hp) infection with the expression of COX-2, EGFR and VEGF in human gastric carcinoma. METHODS: The expression of COX-2, EGFR and VEGF was detected by immunohistochemistry in samples of 61 gastric cancers and 20 cancer-adjacent tissues. Western blotting was performed in samples of 10 gastric cancers and corresponding cancer-adjacent tissues. Hp infection was detected in 47 patients by fast urea enzyme test and (13)C breath test. RESULTS: The results of immunohistochemistry showed that the positive expressions of COX-2, EGFR and VEGF in gastric carcinoma were 59.02%, 36.07% and 60.66%, respectively, significantly higher than that in the normal mucosa (25.00%, 0 and 30.00%, respectively). There was a positive correlation between the expression of COX-2, EGFR and VEGF and gastric carcinoma. The expression of COX-2 and EGFR was 75.76% and 45.45% in the gastric carcinomas with Hp infection, significantly higher than that in those without (28.57% and 14.29%). The protein expression of COX-2, EGFR and VEGF detected by Western blot in gastric carcinomas was also significantly higher than that in normal mucosa. CONCLUSION: COX-2, EGFR and VEGF are overexpressed in gastric carcinoma, and there is a positive correlation among them. Hp infection may upregulate the expression of COX-2 and EGFR in gastric cancer tissues.

PGE2 up-regulates vascular endothelial growth factor expression in MKN28 gastric cancer cells via epidermal growth factor receptor signaling system.

AIM: 1) To evaluate the effect of prostaglandin E2 (PGE2) on the regulation of vascular endothelial growth factor (VEGF) expression in gastric MKN28 cells, and 2) to investigate the role of the epidermal growth factor receptor (EGFR) signal transduction pathway in any effect exerted by PGE2 on VEGF expression. METHODS: MKN28 cells were incubated with the vehicle (control) or with PGE2 in the presence or absence of AG1478, a selective inhibitor of EGFR tyrosine kinase, or PD098059, a selective inhibitor of the kinase responsible for ERK2 phosphorylation (mitogen-activated protein (MAP)/extracellular signal-regulated kinase (ERK)). Real-time quantitative polymerase chain reaction and Western blot analysis were used to evaluate VEGF mRNA and protein expression. The activity of EGFR and ERK2 was measured by Western blot analysis. RESULTS: PGE2 significantly up-regulated VEGF mRNA and protein expression and increased the activation of EGFR and ERK2. Incubation of MKN28 cells with AG1478 significantly reduced PGE2-induced EGFR activity, ERK2 activity, and VEGF mRNA and protein expression. Meanwhile, incubation of MKN28 with PD098059 reduced PGE2-induced ERK2 activity and VEGF mRNA and protein expression, but had no effect on EGFR activity. CONCLUSION: Our data suggested that PGE2 up-regulates VEGF expression in gastric cancer cells via transactivation of EGFR-MAPK signaling pathways, which may be mechanisms underlying the contribution of COX-2 to tumor angiogenesis in gastric cancer.